Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patien... more Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patients with diabetes. However, it is not known if there is an association between sleep apnea, circadian alterations and glycemic regulation in this type of patient. Here, a polysomnographic study was carried out on 21 women and 25 men (mean age = 64.3 ± 1.46 years) with diagnoses of type 2 diabetes to detect the presence of sleep apnea. Moreover, patients wore an actigraph and a temperature sensor on the wrist for one week, to study the manifestation of the circadian rhythms. The correlations of circadian and polysomnographic variables with the severity of apnea, measured by the apnea-hypopnea index, and with glycemic dysregulation, measured by the percentage of glycated hemoglobin, were analyzed. The mean apnea-hypoapnea index of all the participants was 39.6 ± 4.3. Apnea-hypoapnea index correlated with % N1, negatively with % N3, and also the stability of the active circadian rhythm. Howe...
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2001
Lighting conditions influence biological clocks. The present experiment was designed to test the ... more Lighting conditions influence biological clocks. The present experiment was designed to test the presence of a critical window of days during the lactation stage of the rat in which light has a decisive role on the development of the circadian system. Rats were exposed to 4, 8, or 12 days of constant light (LL) during the first days of life. Their circadian rhythm was later studied under LL and constant darkness. The response to a light pulse was also examined. Results show that the greater the number of LL days during lactation, the stronger the rhythm under LL and the smaller the phase shift due to the light pulse. These responses are enhanced when rats are exposed to LL days around postnatal day 12. A mathematical model was built to explain the responses of the circadian system with respect to the timing of LL during lactation, and we deduced that between postnatal days 10 to 20there is a critical period of sensitivity to light; consequently, exposure to LL during this time modif...
Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behavi... more Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behaviour, appetite and body weight. In humans, seasonal variations have been found in certain variables, such as lipid variables and body mass index. We hypothesize that this rhythm could influence the expected variation of the levels of biochemical variables in cases of body weight loss. Thus, the goal of this study was to observe whether the time of year in which bariatric surgery (BS) took place modulated the changes in several variables related to glucidic and lipid metabolism. Blood samples were obtained from 24 women and 10 men before BS and 1 and 3 months after BS. We calculated the percentage of variation that occurred for each individual and for each variable as a function of the time of the year. Data were adjusted to a 12-month period sinusoidal curve, with significance being set at p < 0.05. The results showed that almost all of the studied variables changed due to the BS accor...
The circadian system is organized in a hierarchy of multiple oscillators, with the suprachiasmati... more The circadian system is organized in a hierarchy of multiple oscillators, with the suprachiasmatic nucleus (SCN) as the master oscillator in mammals. The SCN is formed by a group of coupled cell oscillators. Knowledge of this coupling mechanism is essential to understanding entrainment and the expression of circadian rhythms. Some authors suggest that light-dark (LD) cycles with periods near the limit of entrainment may be good models for promoting internal desynchronization, providing knowledge about the coupling mechanism. As such, we evaluated the circadian activity rhythm (CAR) pattern of marmosets in LD cycles at lower limits of entrainment in order to study induced internal dissociation. To that end, two experiments were conducted: (1) 6 adult females were under symmetrical LD cycles T21, T22 and T21.5 for 60, 35 and 48 days, respectively; and (2) 4 male and 4 female adults were under T21 for 24 days followed by 18 days of LL, back to T21 for 24 days, followed by 14 days of LL...
Although intermediate metabolism is known to follow circadian rhythms, little information is avai... more Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year. In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am. Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude). Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter. These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.
Melatonin is a neurohormone with multiple and different actions, such as chronobiotic or antioxid... more Melatonin is a neurohormone with multiple and different actions, such as chronobiotic or antioxidant. Melatonin is usually orally administered, but dermal administration is also useful in dermatological diseases or as adjuvant to certain skin treatments. Here, we studied the variability of the pharmacokinetics of melatonin and its metabolite AFMK, when melatonin is transdermally administered to Hairless rat at two different times of day (Zeitgeber Time 4 (ZT4) and ZT16). Moreover, in order to obtain the bioavailability, kinetics after intravenous administration was also studied. In addition, a permeation study was carried out, at both ZTs, to test the amount of melatonin retained in the skin after transdermal administration. Results showed that pharmacokinetic
UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In ad... more UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In addition, skin sensitivity shows daily variations, which can interfere in the detection of the efficacy of the filters. Here, we studied the UV-induced erythema in hairless rats at two times of the day (light and darkness) using a colorimeter method. The effect of an emulsion with solar filters with or without melatonin was also assayed. Results indicate that the value of a* (from CIELAB color space values L* a* b) was the most useful variable to evaluate the erythema. However, at the UV intensity used, erythema was only detected when irradiation was carried out during the activity phase of the animal, enabling the detection of the protective action of the sunscreen at this time. Thus, daily variations in skin sensitivity have been demonstrated and should be taken into account in dermatological research.
Early lighting conditions have been described to produce long-term effects on circadian behavior,... more Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin (MEL) may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light (LL) in groups of rats that differed in MEL administration and in lighting conditions during suckling. The rats were exposed to either a light-dark cycle (LD) or LL. At 40 days old, rats were treated for 2 weeks with a daily subcutaneous injection of MEL (10 mg/kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase (CAT) activity and nitrite level in plasma. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. MEL treatment produced more reactivity in LD- than in LL...
ABSTRACT To study the hereditary nature of the pattern of the motor activity rhythm in rats, an a... more ABSTRACT To study the hereditary nature of the pattern of the motor activity rhythm in rats, an aggregation method has been developped. Rats of 6 different families belonging to 3 different generations were used for the experiment. Animals were born and raised under LL. Motor activity was recorded by means of an optical detecting system for more than 10 days, depending on the family from the 21st day after birth. A spectral analysis was applied to data corresponding with observation periods equal to the tau of each rat. The mean power spectrum, with 20 harmonics, was calculated for each animal. With the 20 harmonics, the mean power spectrum of each animal can be represented as a point in a 20‐dimensional space. In this space, euclidian distances among the elements were calculated. Then, this cloud of points was projected in a plane. In this plane, if points are considered to have a mass equal to 1, the force that each element is submitted to, due to the attraction of the others, can be calculated. In this sense, a movement in the direction of the force of each element takes place. This process is repeated as many times as necessary to form groups of elements. The results show that at the end of the process, 3 groups of elements are formed. Each group contains the individuals of the families 1, 2 and 3 respectively. This suggests that each family has a characteristic motor activity pattern. Individuals of the third generation (families 4, 5 and 6) were spreaded at random in the three nuclei. This could be due to the assumption that there are mixed characteristics of the previous generations in each animal.
Evolutive aspects of motor activity circadian rhythm have been studied in rats born and reared un... more Evolutive aspects of motor activity circadian rhythm have been studied in rats born and reared under LL, from the day of weaning. Motor activity was recorded by means of an optical detecting system that uses crossed infra‐red beams. Data were recorded every 30 min. A graphic method based in smoothing the double plotted chronograms by means of a moving average
The inherited nature of the pattern of the daily motor activity function (MAF) has been studied u... more The inherited nature of the pattern of the daily motor activity function (MAF) has been studied using different families of the same strain of mice. The motor activity of 6 male mice, belonging to two different families (A and B was recorded during 54 days in LD conditions (12L:12D) using six inductive units. The register began the day just after weaning. A Fourier analysis was applied to motor activity data corresponding to observation periods of 24 hours. The daily power spectrum, with 20 harmonics, was calculated by obtaining the power content of each harmonic expressed as a percentage of the total power content of the MAF. A discriminant function based on the first fifteen harmonics was created to distinguish between the males of the two families. Then, the same discriminant function was applied to the daily power spectra of the progeny. It was also possible to differentiate among the mice (males and females) coming from fathers of family A and the mice coming from fathers of family B (p less than 0.02). This fact suggests that, in the power spectra of the progeny, there may be enough characteristic equal to that of their respective fathers and it further suggests that some characteristic of the MAF could have been inherited.
Differences between sexes in the maturation of the motor activity rhythm have been studied in rat... more Differences between sexes in the maturation of the motor activity rhythm have been studied in rats (10 females and 7 males) born and raised under LL and isolated from the day of weaning. Motor activity data were registered every 30 minutes for 45 days after weaning. Periodogram analysis was applied to each animal data and the daily power spectra were calculated on the basis of the period, tau. The process of rhythm evolution was studied by means of an analysis of variance of a multivariant linear model, and by defining two mathematical functions that fit to the evolution of the total daily motor activity (TDMA) and the power content of the circadian harmonic (PCCH) through time: a sigmoidal function, which presents an inflexion was used for the study of the evolution of the PCCH values through time: and a gaussian function, which presents a minimum was used for the evolution of the TDMA values. Results indicate that males show more ultradian components than females just after weaning, and take a longer time to acquire the circadian harmonic as the main harmonic in the daily power spectrum. The acquisition of the circadian character is preceded by a decrease in the TDMA, in the case of the males and is followed by a decrease in TDMA in the case of the females. These results suggest sexual differences in the organization and maturation of the circadian system in rats.
Los objetivos de este proyecto fueron: a) Identificación de los contenidos fisiológicos y fisiopa... more Los objetivos de este proyecto fueron: a) Identificación de los contenidos fisiológicos y fisiopatológicos que los alumnos deben conocer para el seguimiento de la asignatura de toxicología. b) Unificación terminológica. c) Realización de un conjunto de preguntas básicas sobre estos contenidos. d) Detección, a través de estas preguntas, de los temas o grupos de temas con porcentajes más altos de respuestas incorrectas. e) Detectar los temas de fisiología y fisiopatología en los que hay que hacer más hincapié para favorecer el seguimiento de toxicología. En esta comunicación se describe la experiencia y los resultados obtenidos. ABSTRACT - ENGLISH Learning is a continuous process that should be still performed once a particular subject has been passed. In the university, many subjects require prior knowledge of others subjects for better understanding. During the Pharmacy curriculum of 2002, toxicology teachers observed that students did not seem to remember the basic concepts presuma...
Mice were subjected to three types of acute stress (cold, forced swimming and tail hanging) in or... more Mice were subjected to three types of acute stress (cold, forced swimming and tail hanging) in order to investigate the effects of stress on the motor activity circadian rhythm. This rhythm was studied using the cosinor method and spectral analysis. A statistically significant decrease in the amplitude and the power content of the circadian harmonic was found after stress application. These decreases could be due to a desynchronization of the circadian oscillators which drive the rhythm. The use of the power content of the circadian harmonic is proposed for the detection of the alterations due to stress.
Sound does not entrain the motor activity circadian rhythm of rats. PHYSIOL BEHAV 58(5) 975-978, ... more Sound does not entrain the motor activity circadian rhythm of rats. PHYSIOL BEHAV 58(5) 975-978, 1995.-The effect of sound/silence cycles on the motor activity rhythm of the rat was studied. The daily motor activity pattern was studied in two groups of rats of both sexes kept first under DD and later under LL. One group (16 rats) was subjected to a cycle of sound and silence and the other (8 rats) was used as control. The study was performed under two different light regimes, to consider the possibility that a weak zeitgeber (such as sound might be), would exert an effect on the circadian pacemaker. This effect would depend on the stability of the circadian system, which could be modified by the lighting conditions. Results show no statistically significant differences between the two groups, neither in the motor activity patterns nor in the period of the rhythm. It was concluded that sound is not a zeitgeber for the motor activity rhythm of rats.
The suprachiasmatic nucleus (SCN) coordinates via multiple outputs physiological and behavioural ... more The suprachiasmatic nucleus (SCN) coordinates via multiple outputs physiological and behavioural circadian rhythms. The SCN is composed of a heterogeneous network of coupled oscillators that entrain to the daily light–dark cycles. Outside the physiological entrainment range, rich locomotor patterns of desynchronized rhythms are observed. Previous studies interpreted these results as the output of different SCN neural subpopulations. We find, however, that even a single periodically driven oscillator can induce such complex desynchronized locomotor patterns. Using signal analysis, we show how the observed patterns can be consistently clustered into two generic oscillatory interaction groups: modulation and superposition. In seven of 17 rats undergoing forced desynchronization, we find a theoretically predicted third spectral component. Combining signal analysis with the theory of coupled oscillators, we provide a framework for the study of circadian desynchronization.
Since the suprachiasmatic nuclei (SCN) were identified as the principal mammalian circadian clock... more Since the suprachiasmatic nuclei (SCN) were identified as the principal mammalian circadian clock, many studies describing their morphology and physiology have been carried out. Today, the multioscillatory nature of the SCN, which explains the dissociation of the circadian rhythms under some experimental conditions, is widely accepted. Here, we study the simultaneous presence of two circadian rhythms in the motor activity of the rat when exposed to symmetric light-dark (LD) cycles shorter than 24 h (T21, T21.5, T22, T22.5, T23, and T23.5). One rhythmic component was entrained by the external LD cycle whereas the other ran free with a period longer than 24 h. The results show that two circadian rhythms were present only when T was shorter than T23, whereas at T23.5 only one entrained component was manifested. The manifestation of the two circadian components depends quantitatively on the period of the external cycle-i.e., the strength of the entrained rhythm increases when the external T is closer to 24 h-whereas that of the nonentrained rhythm decreases. The dissociation of the motor activity rhythm and the gradual appearance of the two components are explained by considering the entrainment of a multioscillatory system as not taking place as a whole but rather in a partial manner, in such a way that some oscillators may entrain but not others. The effect of the entrained oscillators is added to the masking effect of the LD cycles.
The implantation of the ECTS as a way of measuring student workload is a challenge both for profe... more The implantation of the ECTS as a way of measuring student workload is a challenge both for professors and for students, since it implies a change not only in the methodology used in the current teaching-learning processes but also in the mentality of both teachers and learners. The new system implies a much narrower interaction between the tasks programmed by the teacher and the activities done by the students. Prior to the implantation of this system, the Group of Teaching Consolidated Innovation "Teaching the Learning of Physiology" of the Department of Physiology of the Pharmacy Faculty of the Universidad de Barcelona already considered it important to know the current state of the methodologies used in the processes of teaching-learning, in order for this to serve as reflection and starting point for implantation of the new system. Thus, the present text shows the results of our research project on teaching, showing evaluation—obtained on the basis of questionnaires—o...
Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patien... more Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patients with diabetes. However, it is not known if there is an association between sleep apnea, circadian alterations and glycemic regulation in this type of patient. Here, a polysomnographic study was carried out on 21 women and 25 men (mean age = 64.3 ± 1.46 years) with diagnoses of type 2 diabetes to detect the presence of sleep apnea. Moreover, patients wore an actigraph and a temperature sensor on the wrist for one week, to study the manifestation of the circadian rhythms. The correlations of circadian and polysomnographic variables with the severity of apnea, measured by the apnea-hypopnea index, and with glycemic dysregulation, measured by the percentage of glycated hemoglobin, were analyzed. The mean apnea-hypoapnea index of all the participants was 39.6 ± 4.3. Apnea-hypoapnea index correlated with % N1, negatively with % N3, and also the stability of the active circadian rhythm. Howe...
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2001
Lighting conditions influence biological clocks. The present experiment was designed to test the ... more Lighting conditions influence biological clocks. The present experiment was designed to test the presence of a critical window of days during the lactation stage of the rat in which light has a decisive role on the development of the circadian system. Rats were exposed to 4, 8, or 12 days of constant light (LL) during the first days of life. Their circadian rhythm was later studied under LL and constant darkness. The response to a light pulse was also examined. Results show that the greater the number of LL days during lactation, the stronger the rhythm under LL and the smaller the phase shift due to the light pulse. These responses are enhanced when rats are exposed to LL days around postnatal day 12. A mathematical model was built to explain the responses of the circadian system with respect to the timing of LL during lactation, and we deduced that between postnatal days 10 to 20there is a critical period of sensitivity to light; consequently, exposure to LL during this time modif...
Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behavi... more Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behaviour, appetite and body weight. In humans, seasonal variations have been found in certain variables, such as lipid variables and body mass index. We hypothesize that this rhythm could influence the expected variation of the levels of biochemical variables in cases of body weight loss. Thus, the goal of this study was to observe whether the time of year in which bariatric surgery (BS) took place modulated the changes in several variables related to glucidic and lipid metabolism. Blood samples were obtained from 24 women and 10 men before BS and 1 and 3 months after BS. We calculated the percentage of variation that occurred for each individual and for each variable as a function of the time of the year. Data were adjusted to a 12-month period sinusoidal curve, with significance being set at p < 0.05. The results showed that almost all of the studied variables changed due to the BS accor...
The circadian system is organized in a hierarchy of multiple oscillators, with the suprachiasmati... more The circadian system is organized in a hierarchy of multiple oscillators, with the suprachiasmatic nucleus (SCN) as the master oscillator in mammals. The SCN is formed by a group of coupled cell oscillators. Knowledge of this coupling mechanism is essential to understanding entrainment and the expression of circadian rhythms. Some authors suggest that light-dark (LD) cycles with periods near the limit of entrainment may be good models for promoting internal desynchronization, providing knowledge about the coupling mechanism. As such, we evaluated the circadian activity rhythm (CAR) pattern of marmosets in LD cycles at lower limits of entrainment in order to study induced internal dissociation. To that end, two experiments were conducted: (1) 6 adult females were under symmetrical LD cycles T21, T22 and T21.5 for 60, 35 and 48 days, respectively; and (2) 4 male and 4 female adults were under T21 for 24 days followed by 18 days of LL, back to T21 for 24 days, followed by 14 days of LL...
Although intermediate metabolism is known to follow circadian rhythms, little information is avai... more Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year. In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am. Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude). Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter. These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.
Melatonin is a neurohormone with multiple and different actions, such as chronobiotic or antioxid... more Melatonin is a neurohormone with multiple and different actions, such as chronobiotic or antioxidant. Melatonin is usually orally administered, but dermal administration is also useful in dermatological diseases or as adjuvant to certain skin treatments. Here, we studied the variability of the pharmacokinetics of melatonin and its metabolite AFMK, when melatonin is transdermally administered to Hairless rat at two different times of day (Zeitgeber Time 4 (ZT4) and ZT16). Moreover, in order to obtain the bioavailability, kinetics after intravenous administration was also studied. In addition, a permeation study was carried out, at both ZTs, to test the amount of melatonin retained in the skin after transdermal administration. Results showed that pharmacokinetic
UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In ad... more UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In addition, skin sensitivity shows daily variations, which can interfere in the detection of the efficacy of the filters. Here, we studied the UV-induced erythema in hairless rats at two times of the day (light and darkness) using a colorimeter method. The effect of an emulsion with solar filters with or without melatonin was also assayed. Results indicate that the value of a* (from CIELAB color space values L* a* b) was the most useful variable to evaluate the erythema. However, at the UV intensity used, erythema was only detected when irradiation was carried out during the activity phase of the animal, enabling the detection of the protective action of the sunscreen at this time. Thus, daily variations in skin sensitivity have been demonstrated and should be taken into account in dermatological research.
Early lighting conditions have been described to produce long-term effects on circadian behavior,... more Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin (MEL) may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light (LL) in groups of rats that differed in MEL administration and in lighting conditions during suckling. The rats were exposed to either a light-dark cycle (LD) or LL. At 40 days old, rats were treated for 2 weeks with a daily subcutaneous injection of MEL (10 mg/kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase (CAT) activity and nitrite level in plasma. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. MEL treatment produced more reactivity in LD- than in LL...
ABSTRACT To study the hereditary nature of the pattern of the motor activity rhythm in rats, an a... more ABSTRACT To study the hereditary nature of the pattern of the motor activity rhythm in rats, an aggregation method has been developped. Rats of 6 different families belonging to 3 different generations were used for the experiment. Animals were born and raised under LL. Motor activity was recorded by means of an optical detecting system for more than 10 days, depending on the family from the 21st day after birth. A spectral analysis was applied to data corresponding with observation periods equal to the tau of each rat. The mean power spectrum, with 20 harmonics, was calculated for each animal. With the 20 harmonics, the mean power spectrum of each animal can be represented as a point in a 20‐dimensional space. In this space, euclidian distances among the elements were calculated. Then, this cloud of points was projected in a plane. In this plane, if points are considered to have a mass equal to 1, the force that each element is submitted to, due to the attraction of the others, can be calculated. In this sense, a movement in the direction of the force of each element takes place. This process is repeated as many times as necessary to form groups of elements. The results show that at the end of the process, 3 groups of elements are formed. Each group contains the individuals of the families 1, 2 and 3 respectively. This suggests that each family has a characteristic motor activity pattern. Individuals of the third generation (families 4, 5 and 6) were spreaded at random in the three nuclei. This could be due to the assumption that there are mixed characteristics of the previous generations in each animal.
Evolutive aspects of motor activity circadian rhythm have been studied in rats born and reared un... more Evolutive aspects of motor activity circadian rhythm have been studied in rats born and reared under LL, from the day of weaning. Motor activity was recorded by means of an optical detecting system that uses crossed infra‐red beams. Data were recorded every 30 min. A graphic method based in smoothing the double plotted chronograms by means of a moving average
The inherited nature of the pattern of the daily motor activity function (MAF) has been studied u... more The inherited nature of the pattern of the daily motor activity function (MAF) has been studied using different families of the same strain of mice. The motor activity of 6 male mice, belonging to two different families (A and B was recorded during 54 days in LD conditions (12L:12D) using six inductive units. The register began the day just after weaning. A Fourier analysis was applied to motor activity data corresponding to observation periods of 24 hours. The daily power spectrum, with 20 harmonics, was calculated by obtaining the power content of each harmonic expressed as a percentage of the total power content of the MAF. A discriminant function based on the first fifteen harmonics was created to distinguish between the males of the two families. Then, the same discriminant function was applied to the daily power spectra of the progeny. It was also possible to differentiate among the mice (males and females) coming from fathers of family A and the mice coming from fathers of family B (p less than 0.02). This fact suggests that, in the power spectra of the progeny, there may be enough characteristic equal to that of their respective fathers and it further suggests that some characteristic of the MAF could have been inherited.
Differences between sexes in the maturation of the motor activity rhythm have been studied in rat... more Differences between sexes in the maturation of the motor activity rhythm have been studied in rats (10 females and 7 males) born and raised under LL and isolated from the day of weaning. Motor activity data were registered every 30 minutes for 45 days after weaning. Periodogram analysis was applied to each animal data and the daily power spectra were calculated on the basis of the period, tau. The process of rhythm evolution was studied by means of an analysis of variance of a multivariant linear model, and by defining two mathematical functions that fit to the evolution of the total daily motor activity (TDMA) and the power content of the circadian harmonic (PCCH) through time: a sigmoidal function, which presents an inflexion was used for the study of the evolution of the PCCH values through time: and a gaussian function, which presents a minimum was used for the evolution of the TDMA values. Results indicate that males show more ultradian components than females just after weaning, and take a longer time to acquire the circadian harmonic as the main harmonic in the daily power spectrum. The acquisition of the circadian character is preceded by a decrease in the TDMA, in the case of the males and is followed by a decrease in TDMA in the case of the females. These results suggest sexual differences in the organization and maturation of the circadian system in rats.
Los objetivos de este proyecto fueron: a) Identificación de los contenidos fisiológicos y fisiopa... more Los objetivos de este proyecto fueron: a) Identificación de los contenidos fisiológicos y fisiopatológicos que los alumnos deben conocer para el seguimiento de la asignatura de toxicología. b) Unificación terminológica. c) Realización de un conjunto de preguntas básicas sobre estos contenidos. d) Detección, a través de estas preguntas, de los temas o grupos de temas con porcentajes más altos de respuestas incorrectas. e) Detectar los temas de fisiología y fisiopatología en los que hay que hacer más hincapié para favorecer el seguimiento de toxicología. En esta comunicación se describe la experiencia y los resultados obtenidos. ABSTRACT - ENGLISH Learning is a continuous process that should be still performed once a particular subject has been passed. In the university, many subjects require prior knowledge of others subjects for better understanding. During the Pharmacy curriculum of 2002, toxicology teachers observed that students did not seem to remember the basic concepts presuma...
Mice were subjected to three types of acute stress (cold, forced swimming and tail hanging) in or... more Mice were subjected to three types of acute stress (cold, forced swimming and tail hanging) in order to investigate the effects of stress on the motor activity circadian rhythm. This rhythm was studied using the cosinor method and spectral analysis. A statistically significant decrease in the amplitude and the power content of the circadian harmonic was found after stress application. These decreases could be due to a desynchronization of the circadian oscillators which drive the rhythm. The use of the power content of the circadian harmonic is proposed for the detection of the alterations due to stress.
Sound does not entrain the motor activity circadian rhythm of rats. PHYSIOL BEHAV 58(5) 975-978, ... more Sound does not entrain the motor activity circadian rhythm of rats. PHYSIOL BEHAV 58(5) 975-978, 1995.-The effect of sound/silence cycles on the motor activity rhythm of the rat was studied. The daily motor activity pattern was studied in two groups of rats of both sexes kept first under DD and later under LL. One group (16 rats) was subjected to a cycle of sound and silence and the other (8 rats) was used as control. The study was performed under two different light regimes, to consider the possibility that a weak zeitgeber (such as sound might be), would exert an effect on the circadian pacemaker. This effect would depend on the stability of the circadian system, which could be modified by the lighting conditions. Results show no statistically significant differences between the two groups, neither in the motor activity patterns nor in the period of the rhythm. It was concluded that sound is not a zeitgeber for the motor activity rhythm of rats.
The suprachiasmatic nucleus (SCN) coordinates via multiple outputs physiological and behavioural ... more The suprachiasmatic nucleus (SCN) coordinates via multiple outputs physiological and behavioural circadian rhythms. The SCN is composed of a heterogeneous network of coupled oscillators that entrain to the daily light–dark cycles. Outside the physiological entrainment range, rich locomotor patterns of desynchronized rhythms are observed. Previous studies interpreted these results as the output of different SCN neural subpopulations. We find, however, that even a single periodically driven oscillator can induce such complex desynchronized locomotor patterns. Using signal analysis, we show how the observed patterns can be consistently clustered into two generic oscillatory interaction groups: modulation and superposition. In seven of 17 rats undergoing forced desynchronization, we find a theoretically predicted third spectral component. Combining signal analysis with the theory of coupled oscillators, we provide a framework for the study of circadian desynchronization.
Since the suprachiasmatic nuclei (SCN) were identified as the principal mammalian circadian clock... more Since the suprachiasmatic nuclei (SCN) were identified as the principal mammalian circadian clock, many studies describing their morphology and physiology have been carried out. Today, the multioscillatory nature of the SCN, which explains the dissociation of the circadian rhythms under some experimental conditions, is widely accepted. Here, we study the simultaneous presence of two circadian rhythms in the motor activity of the rat when exposed to symmetric light-dark (LD) cycles shorter than 24 h (T21, T21.5, T22, T22.5, T23, and T23.5). One rhythmic component was entrained by the external LD cycle whereas the other ran free with a period longer than 24 h. The results show that two circadian rhythms were present only when T was shorter than T23, whereas at T23.5 only one entrained component was manifested. The manifestation of the two circadian components depends quantitatively on the period of the external cycle-i.e., the strength of the entrained rhythm increases when the external T is closer to 24 h-whereas that of the nonentrained rhythm decreases. The dissociation of the motor activity rhythm and the gradual appearance of the two components are explained by considering the entrainment of a multioscillatory system as not taking place as a whole but rather in a partial manner, in such a way that some oscillators may entrain but not others. The effect of the entrained oscillators is added to the masking effect of the LD cycles.
The implantation of the ECTS as a way of measuring student workload is a challenge both for profe... more The implantation of the ECTS as a way of measuring student workload is a challenge both for professors and for students, since it implies a change not only in the methodology used in the current teaching-learning processes but also in the mentality of both teachers and learners. The new system implies a much narrower interaction between the tasks programmed by the teacher and the activities done by the students. Prior to the implantation of this system, the Group of Teaching Consolidated Innovation "Teaching the Learning of Physiology" of the Department of Physiology of the Pharmacy Faculty of the Universidad de Barcelona already considered it important to know the current state of the methodologies used in the processes of teaching-learning, in order for this to serve as reflection and starting point for implantation of the new system. Thus, the present text shows the results of our research project on teaching, showing evaluation—obtained on the basis of questionnaires—o...
Uploads
Papers by Trinitat Cambras