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It appears that the effect of acute administration of pituitary-adrenal hormones on the pituitary-gonadal axis is species-dependent. However, no information is available with regard to the effect of acute adrenocorticotropin (ACTH)... more
It appears that the effect of acute administration of pituitary-adrenal hormones on the pituitary-gonadal axis is species-dependent. However, no information is available with regard to the effect of acute adrenocorticotropin (ACTH) administration on testosterone secretion in rats. The present data indicate that acute ACTH administration can increase serum testosterone levels without modifying luteinizing hormone (LH) levels. Since this rise was not observed in castrated rats, it must be assumed that increased serum testosterone was of gonadal origin. The action of ACTH on testosterone secretion was likely an indirect one since there is no evidence at present for a direct, short-term action of the pituitary-adrenal axis on Leydig cell function.
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ABSTRACT The effect of chronic noise stress on the response of anterior pituitary hormones to the same or to another stressor (forced swimming) was studied in adult male Wistar rats. Both acute stressors increased corticosterone,... more
ABSTRACT The effect of chronic noise stress on the response of anterior pituitary hormones to the same or to another stressor (forced swimming) was studied in adult male Wistar rats. Both acute stressors increased corticosterone, prolactin, LH and TSH secretion and inhibited GH secretion. Previous chronic exposure to noise reduced corticosterone response to the same stimulus without modifying corticosterone response to a novel acute stress. Neither prolactin nor TSH responses to acute noise were reduced by previous chronic exposure to noise. Since chronic noise increased basal levels of LH and decreased those of GH, the response of these hormones to acute stress was expressed as percent changes of their respective basal values. It was found that chronically stressed rats showed diminished LH response to noise but not to forced swimming. GH showed the same pattern without reaching statistical significance. These data indicate that the response of some anterior pituitary hormones can adapt after repeated exposure to the same stressor. When adaptation occurred, this was specific for the stressor which the animals were repeatedly exposed to. The pituitary-adrenal axis appears to be the most reliable index of adaptation to chronic stress among all the anterior pituitary endocrine axes.
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Research Interests: Medicine, Biological Sciences, Circadian Rhythm, Animals, Male, and 14 moreFeeding Behavior, Food intake, Arousal, Rats, Chronic Stress, Anorexia, Body Weight, Physical Restraint, Psychological Stress, Motor activity, Adrenal glands, Psychology and Cognitive Sciences, Medical and Health Sciences, and stressor
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Abstract 1. Chronic stress did not alter basal levels of luteinizing hormone (LH) or prolactin (PRL) in adult male rats relative to unstressed controls. However, slightly reduced LH and PRL levels were observed in response to a novel... more
Abstract 1. Chronic stress did not alter basal levels of luteinizing hormone (LH) or prolactin (PRL) in adult male rats relative to unstressed controls. However, slightly reduced LH and PRL levels were observed in response to a novel acute stressor in chronically stressed Ss ...
Research Interests: Psychology, Medicine, Biological Sciences, Biological Psychiatry, Prolactin, and 15 moreAnimals, Male, Animal Model, Depressive Disorder, Arousal, Rats, Chronic Stress, Luteinizing Hormone, Psychological Stress, Acute stress, Psychology and Cognitive Sciences, Endocrine System, Medical and Health Sciences, stressor, and Male rat
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The effect of water restriction on the pituitary-gonadal axis has been studied in adult male rats. Water restriction did not modify FSH, LH and testosterone levels. However, both LH and testosterone responses to acute noise stress were... more
The effect of water restriction on the pituitary-gonadal axis has been studied in adult male rats. Water restriction did not modify FSH, LH and testosterone levels. However, both LH and testosterone responses to acute noise stress were impaired by water restriction. It was unlikely that the inhibition of the pituitary-gonadal response to stress was due to an alteration of the circadian pattern of LH since no evidence for such a daily rhythm was found in either of the two experimental groups. The effects of water restriction on the pituitary-gonadal axis appear to be at least partially a consequence of the resulting reduction in food intake, so that the pituitary-gonadal response to stress would be a more sensitive index of abnormalities induced by protein-calorie deficit than basal concentrations of LH, FSH, or T.
Research Interests: Endocrinology, Andrology, Biology, Medicine, Internal Medicine, and 15 moreCircadian Rhythm, Animals, Corticosterone, Male, Crowding, Endocrine, Clinical Sciences, Body Weight, Physiological Stress Markers, Luteinizing Hormone, Follicle stimulating hormone, Gonads, Adrenal glands, Paediatrics and reproductive medicine, and Male rat
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Exposure of rodents to cats or certain cat odors results in long-term behavioral effects reminiscent of enhanced anxiety that have been considered to model post-traumatic stress disorder. However, other severe stressors such as tail-shock... more
Exposure of rodents to cats or certain cat odors results in long-term behavioral effects reminiscent of enhanced anxiety that have been considered to model post-traumatic stress disorder. However, other severe stressors such as tail-shock or immobilization in wooden boards (IMO) appear to induce shorter lasting changes in anxiety. In addition, there are controversial results regarding the effects of urine/feces odors. In the present work, we studied in two experiments the relationship between the degree of stress experienced by the animals during exposure to IMO, urine odors or fur odors (as assessed by hypothalamic-pituitary-adrenal activation and plasma glucose) and the short- and long-term behavioral consequences. In the first experiment, rats were individually exposed for 15 min to a novel environment (white large cages) containing either clean cat litter (controls) or litter soiled by cats (urine odors). Half of the rats in each condition were left to freely explore the environment whereas the others were subjected to immobilization (IMO) within the cages. Although ACTH, corticosterone and glucose responses to IMO were much stronger than those to the white cages with clean litter or urine odors (which did not differ from each other), no effect of treatments on anxiety-like behavior in the elevated plus-maze (EPM) were found one week later. However, previous IMO exposure did cause sensitization of the ACTH response to the EPM. In the second experiment, the response to white large cages containing either no odor (controls), litter soiled by cats (urine odor) or a cloth impregnated with cat odor (fur odor) was compared. Urine and fur odors elicited similar ACTH and corticosterone responses that were higher than those of controls, but plasma glucose levels were slightly higher in rats exposed to fur odor. When compared to controls, activity was only diminished in the novel cages containing fur odor. Similarly, fur odor-exposed rats, but not those exposed to urine odor, showed signs of enhanced anxiety in the EPM seven days later, although the ACTH response to the EPM was similar in the three groups. The present data demonstrate: (a) a marked dissociation between the degree of ACTH, corticosterone and glucose responses to stressors and their long-term anxiety-like effects; (b) that the type of cat odor is critical in determining the short-term and long-term physiological and behavioral consequences of exposure; and (c) that plasma ACTH released during brief exposure to the EPM does not appear to reflect anxiety-like behavior.
Research Interests: Endocrinology, Chemistry, Animal Behavior, Medicine, Anxiety, and 15 moreCats, Post traumatic stress disorder, Internal Medicine, Blood Glucose, Animals, Corticosterone, Male, ODOR, Litter, Odors, Elevated Plus Maze, Adrenocorticotropic Hormone, ANXIETY, Physical Restraint, and Medical and Health Sciences
Research Interests: Endocrinology, Aging, Biology, Medicine, Animal Production, and 15 moreProlactin, Internal Medicine, Testosterone, Animals, Corticosterone, Male, Clinical Sciences, Rats, Adrenocorticotropic Hormone, Physiological Stress Markers, Luteinizing Hormone, Acute stress, Acute Disease, Stress Physiological, and Male rat
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Research Interests: Endocrinology, Life Sciences, Medicine, Prolactin, Internal Medicine, and 15 moreAnimals, Corticosterone, Male, Arousal, Rats, Hormone, Physiological Stress Markers, Luteinizing Hormone, Psychological Stress, Follicle stimulating hormone, Anterior Pituitary, Biochemistry and cell biology, Stress Physiological, Pharmacology and pharmaceutical sciences, and stressor
Research Interests: Endocrinology, Psychology, Medicine, Habituation, Internal Medicine, and 14 moreBlood Glucose, Animals, Male, Psychoneuroendocrinology, Feeding Behavior, Rats, Body Weight, Physical Restraint, Psychological Stress, Acute stress, Adrenal glands, Psychology and Cognitive Sciences, Medical and Health Sciences, and stressor
Research Interests: Endocrinology, Biology, Gene expression, Corticotropin Releasing Hormone, Growth Hormone, and 15 moreBrain, Hypothalamus, Animals, Corticosterone, HPA axis, Animal Model, Clinical Sciences, European, Growth rate, Adrenocorticotropic Hormone, Glucocorticoids, DNA probes, Gene Expression Regulation, Corticotrophin Releasing Factor, and Hippocampal formation
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The effect of alpha-tocopherol or ascorbic acid jointly and separately on the seric levels of adrenocorticotropin (ACTH) and corticosterone has been studied. ACTH response to stress is similar in all groups, whereas the corticosterone... more
The effect of alpha-tocopherol or ascorbic acid jointly and separately on the seric levels of adrenocorticotropin (ACTH) and corticosterone has been studied. ACTH response to stress is similar in all groups, whereas the corticosterone response is higher in the animals treated with alpha-tocopherol. Neither lactate response nor gastric ulceration caused by stress was influenced by the administration of alpha-tocopherol and/or ascorbic acid. These results suggest that free radicals might not be implicated in the control of the physiological response to stress.
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Research Interests: Endocrinology, Biology, Life Sciences, Medicine, Internal Medicine, and 14 moreAnimals, Male, Rats, Analysis of Variance, Chronic Stress, Anorexia, Physiological Stress Markers, Luteinizing Hormone, Immobilization, Biochemistry and cell biology, Random Allocation, Stress Physiological, Pharmacology and pharmaceutical sciences, and stressor
Most drugs of abuse stimulate both locomotor activity and the hypothalamic-pituitary-adrenal (HPA) axis, but the relationship between the two responses within the same subjects and their reliabilities has been scarcely studied. Our... more
Most drugs of abuse stimulate both locomotor activity and the hypothalamic-pituitary-adrenal (HPA) axis, but the relationship between the two responses within the same subjects and their reliabilities has been scarcely studied. Our objectives were to study: (1) the consistency and stability across time of locomotor and HPA activation induced by repeated d-amphetamine (AMPH); (2) the relationship between locomotor and hormonal responses to AMPH; and (3) the relationship between novelty-induced activity and both types of responses to the drug. Male adult rats were exposed to a novel environment to study the locomotor response. Later, they were injected with AMPH (2 mg/kg, sc) for 5 days. In Experiment 1, Plasma adrenocorticotropin (ACTH) and corticosterone levels in response to AMPH were studied on days 1, 3, and 5, and locomotor response on days 2 and 4. In Experiment 2, ACTH and corticosterone responses were studied on days 2 and 4, and locomotor response on days 1, 3, and 5. Across days, both locomotor and HPA responses to the drug were consistent, but independent measures, unrelated to the reactivity to novelty. As measured by the area under the curve, the HPA response to AMPH desensitized with the repeated injection, whereas the initial locomotor response to the drug increased. Dissociation exists between HPA and locomotor activation induced by AMPH, which seemed to be both reliable individual traits. Locomotor reactivity to novelty was related neither to HPA nor to locomotor responses to AMPH.
Research Interests: Endocrinology, Medicine, Individual Differences, Dissociation, Internal Medicine, and 15 moreAnimals, Corticosterone, Male, Amphetamine, HPA axis, Consistency, Adrenocorticotropic Hormone, Locomotor Activity, Drugs of Abuse, Area Under the Curve, Environment, Area Under Curve, Dextroamphetamine, Central nervous system stimulants, and Medical and Health Sciences
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Sleep plays a crucial role in cognitive processes. Sleep and wake memory consolidation seem to be regulated by glucocorticoids, pointing out the potential role of the hypothalamic-pituitary-adrenal (HPA) axis in the relationship between... more
Sleep plays a crucial role in cognitive processes. Sleep and wake memory consolidation seem to be regulated by glucocorticoids, pointing out the potential role of the hypothalamic-pituitary-adrenal (HPA) axis in the relationship between sleep quality and cognitive abilities. Trait anxiety is another factor that is likely to moderate the relationship between sleep and cognition, because poorer sleep quality and subtle HPA axis abnormalities have been reported in people with high trait anxiety. The current study aimed to explore whether HPA axis activity or trait anxiety moderate the relationship between sleep quality and cognitive abilities in healthy individuals. We studied 203 healthy individuals. We measured verbal and visual memory, working memory, processing speed, attention and executive function. Sleep quality was assessed with the Pittsburgh Sleep Quality Index. Trait anxiety was assessed with the State-Trait Anxiety Inventory. HPA axis measures included the cortisol awakenin...
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Hypothalamic-pituitary-adrenal (HPA) axis alterations in at-risk mental states (ARMS) resemble those observed in established psychosis but are less consistent. We aimed to explore HPA axis abnormalities in both first-episode psychosis... more
Hypothalamic-pituitary-adrenal (HPA) axis alterations in at-risk mental states (ARMS) resemble those observed in established psychosis but are less consistent. We aimed to explore HPA axis abnormalities in both first-episode psychosis (FEP) and ARMS patients, while controlling for psychopathological symptoms. We studied 21 ARMS, 34 FEP patients and 34 healthy subjects. Clinical assessment included psychopathological symptoms (positive, negative, disorganized, excited and depressive symptoms) and stress measures. Saliva cortisol levels were determined at awakening, 30' and 60' post-awakening, 10:00 h, 23:00 h and 10:00 h on the day after the administration of 0.25 mg of dexamethasone, which occurred at 23:00 h. Three HPA axis measures were calculated: cortisol awakening response (CAR), cortisol diurnal slope and cortisol suppression ratio of the dexamethasone suppression test (DST). There were no significant differences between groups in HPA axis measures. However, when explo...
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Early life stress (ELS) induces long-term effects in later functioning and interacts with further exposure to other stressors in adulthood to shape our responsiveness to reward-related cues. The attribution of incentive salience to... more
Early life stress (ELS) induces long-term effects in later functioning and interacts with further exposure to other stressors in adulthood to shape our responsiveness to reward-related cues. The attribution of incentive salience to food-related cues may be modulated by previous and current exposures to stressors in a sex-dependent manner. We hypothesized from human data that exposure to a traumatic (severe) adult stressor will decrease the attribution of incentive salience to reward-associated cues, especially in females, because these effects are modulated by previous ELS. To study these factors in Long-Evans rats, we used as an ELS model of restriction of nesting material and concurrently evaluated maternal care. In adulthood, the offspring of both sexes were exposed to acute immobilization (IMO), and several days after, a Pavlovian conditioning procedure was used to assess the incentive salience of food-related cues. Some rats developed more attraction to the cue predictive of re...
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The effects of chronic stress on the hypothalamic-pituaitary-adrenocortical (HPA) axis were studied in five inbred rat strains, i.e. Brown Norway (BN), Fischer (FIS), Lewis (LEW), Spontaneously Hypertensive (SHR) and Wistar Kyoto (WKY).... more
The effects of chronic stress on the hypothalamic-pituaitary-adrenocortical (HPA) axis were studied in five inbred rat strains, i.e. Brown Norway (BN), Fischer (FIS), Lewis (LEW), Spontaneously Hypertensive (SHR) and Wistar Kyoto (WKY). Previously, these rat strains had been shown to display clear behavioral differences in the forced swimming test that presumably measures depression-like behavior, BN and WKY being more passive than the other strains. Here we test the hypothesis that the differences in behavioral immobility might be associated with an abnormal HPA response to chronic immobilization (IMO) stress. In stressnaive rats under basal conditions (morning) there were no differences among strains in adrenal weight, serum adrenocorticotropin hormone (ACTH) and corticosterone (B) levels, cortictropin-releasing factor (CRF) mRNA in the hypothalamic paraventricular nucleus (PVN) and hippocampal glucocorticoid and mineralocorticoid receptor (GR and MR) mRNA. After chronic IMO, basal serum ACTH levels were increased in LEW, SHR and WKY, but not in BN or FIS rats, whereas basal B levels were increased in BN, FIS, SHR and WKY rats, but not in LEW. The increase in adrenal weight was also strain dependent and correlated negatively with chronic IMO-induced hypercorticosteronemia. These peripheral differences among strains were not observed at central levels. Thus, chronic IMO increased the CRF mRNA content in the PVN, analyzed by in situ hybridization, similarly in all strains. In addition, after chronic IMO no differences were found among strains in hippocampal GR mRNA and RM mRNA contents. Considering data from all strains together, chronic IMO reduced the GR mRNA (50-60%) content in the hippocampal CA1, CA3 and DG areas, and slightly diminished (11-13%) MR mRNA levels in CA1 and CA3 areas. The present results indicate that: (i) chronic IMO down-regulates GR mRNA in the hippocampus and slightly up-regulates CRF mRNA in the hypothalamic PVN similarly in all strains; (ii) after chronic IMO interstrain differences were observed in serum ACTH and B levels as well as adrenal hypertrophy; (iii) some changes are probably located at the adrenal level since changes in serum B level and adrenal weight were not related to changes in ACTH; (iv) in LEW and WKY rats, B hyporesponsiveness to chronic IMO might be linked to low adrenal sensitivity to ACTH, and (v) HPA axis changes induced by the chronic IMO procedure are not related to previously reported data on depressive-like behavior of BN and WKY in the forced swimming test.
Research Interests: Neuroendocrinology, Corticotropin Releasing Hormone, In Situ Hybridization, Animals, Corticosterone, and 15 moreMale, HPA axis, Paraventricular Nucleus, Clinical Sciences, Rats, Adrenal cortex, Forced Swim Test, Chronic Stress, Body Weight, Species Specificity, Spontaneously Hypertensive Rats, Psychological Stress, Mineralocorticoid Receptor, Neurosciences, and Glucocorticoids
The study concerned the effects of acute and chronic clomipramine administration to male rats on exploratory activity in a novel environment (hole-board) and on immobility in the forced swimming test. Acute clomipramine administration did... more
The study concerned the effects of acute and chronic clomipramine administration to male rats on exploratory activity in a novel environment (hole-board) and on immobility in the forced swimming test. Acute clomipramine administration did not alter either exploratory activity on a hole-board as measured 3 or 20 h after drug administration, or immobility in the forced swimming test as measured 20 h after drug administration. Approximately 20 h after the last injection of clomipramine, the rats chronically treated with the drug showed reduced exploratory activity on the hole-board. In contrast, chronic clomipramine treatment significantly increased the activity in the forced swimming test. The effects of the drug on exploratory and forced swimming activities persisted for 14 days after the cessation of clomipramine administration. These data indicate that chronic clomipramine administration exerted profound and long-lasting effects on central nervous system function. The long-lasting action of the drug on behaviour in the forced swimming test might explain the long-term beneficial effect of antidepressant drugs in counteracting behavioral depression.
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Research Interests: Genetics, Animal Behavior, Coping Strategies, Behavior, Anxiety, and 15 morePost traumatic stress disorder, Models, Major Depressive Disorder, Mice, Circadian Rhythm, Animals, Corticosterone, Panic Disorder, HPA axis, Mouse Model, Chronic Stress, Psychiatric, ANXIETY, Acute stress, and Medical and Health Sciences
Pathological consequences of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis may be related to the duration rather than to the intensity of HPA axis activation after exposure to the stressor. Consequently a fine... more
Pathological consequences of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis may be related to the duration rather than to the intensity of HPA axis activation after exposure to the stressor. Consequently a fine analysis of post-stress events is of importance. The present experiments were designed to study the importance of three key factors in HPA recovery: intensity of the stressor (experiment 1), duration of exposure to the stressor (experiment 2) and previous experience of the animals with the situation (experiments 3 and 4). In experiment 1, analysis of both the response to the stressor and the poststress period showed that the stronger the stressor, the greater the area under the curve of HPA activation. In experiment 2, different groups of rats were exposed to different periods of immobilization (IMO) (20 min, 1 h and 2 h) and sampled before, during and after exposure to IMO. The speed of recovery of plasma corticotropin (ACTH) levels was not related to the duration of exposure to the stressor. In experiments 3 and 4, the influence of previous experience with the stressor was studied in rats daily exposed to 20 min IMO or daily injected with hypertonic saline (HS) for 8 days and sampled on days 1, 2, 5 and 8. Whereas a significant decline in plasma ACTH levels was not observed immediately after IMO until day 8, a single previous exposure to IMO was enough to enhance recovery 90 min after the end of exposure to IMO. Corticosterone levels were related to the number of previous experiences with the stressor only in the post-IMO period. In response to a novel stressor (forced swimming), chronic IMO rats showed a slightly impaired recovery as compared to stress-naive rats, suggesting that enhanced recovery of the HPA axis was specific for the homotypic stressor. After daily HS injections, a pattern similar to that after IMO was observed, the delayed, but not the early response of the HPA axis being reduced as a function of the number of previous experiences with the situation. Taken together, the present results suggest that the speed of recovery of the HPA axis after its activation by stressors is sensitive to the intensity of the stressors but not to their duration, and that adaptation to a repeated stressor is more apparent during the delayed HPA response.
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Martí O, Gavaldà A, Jolín T, Armario A. Acute stress attenuates but does not abolish circadian rhythmicity of serum thyrotrophin and growth hormone in the rat. Eur J Endocrinol 1996;135:703–8. ISSN 0804–4643 The effects of acute... more
Martí O, Gavaldà A, Jolín T, Armario A. Acute stress attenuates but does not abolish circadian rhythmicity of serum thyrotrophin and growth hormone in the rat. Eur J Endocrinol 1996;135:703–8. ISSN 0804–4643 The effects of acute immobilization (IMO) on daily rhythms of corticosterone, thyroid-stimulating hormone (TSH) and growth hormone (GH) were studied in adult male rats. Two hours of IMO increased serum corticosterone, this increase still being observed 3 h after finishing stress exposure. In the dark period corticosterone levels did not differ in control and IMO rats, but higher levels were observed again in the morning of the day after. Immobilization lowered serum GH and TSH levels throughout the 24-h period that followed exposure to the stressor. Such an effect was more marked in GH than in TSH. In addition, GH, but not TSH, levels were found to be reduced significantly by IMO at 08.30 h of the next day. None the less, daily rhythms of GH and TSH were still persistent and roughly similar to those of control rats. The daily rhythm of food intake was measured in a separate experiment and it was observed, as expected, that IMO reduced food intake only in the dark period of the lighting cycle. It appears therefore unlikely that IMO-induced anorexia was the major factor responsible for the inhibition of GH and TSH caused by IMO at 11.00 and 19.00 h, considering that the amount of food intake was very low and similar in control and IMO rats during this period. However, anorexia might have contributed to inhibition of GH and TSH secretion afterwards. Thus, in a third experiment we studied the contribution of IMO-induced anorexia to the changes in hormone levels observed 24 h after stress by introducing a group of pair-fed rats. It was found that IMO, but not pair-feeding, reduced TSH levels, whereas a similar reduction of GH was found in the two conditions. It might be concluded that acute stress transiently altered corticosterone secretion, the only long-lasting effect being a slight increase in its morning levels on the following stress. Immobilization also causes an inhibition of GH and TSH secretion in the rat that persists for several hours after finalization of exposure to the stressor, but daily rhythms were still apparent. It appears that the contribution of stress-induced anorexia is different in GH than in TSH. In conclusion, an acute severe stressor such as IMO, although modifying circulating levels of some hormones, particularly in the hours following exposure to the stressor, did not appear to interfere greatly with the expression of circadian rhythms of anterior pituitary hormones. Octavi Martí, Unitat de Fisiologia Animal, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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The effect of regularity of exposure to two different chronic stressors (noise or immobilization (IMO)) on the pattern of habituation of pituitary-adrenal (PA) hormones, prolactin and glucose was evaluated in adult male rats. Animals were... more
The effect of regularity of exposure to two different chronic stressors (noise or immobilization (IMO)) on the pattern of habituation of pituitary-adrenal (PA) hormones, prolactin and glucose was evaluated in adult male rats. Animals were chronically subjected to either regular or irregular time schedule of noise (30 min/day) or IMO (2 h/day) for two weeks. The day after the last stress session the rats were killed without stress or after having been subjected to 30 min of the homotypic stressor. Whereas regular noise did not affect food intake, body weight gain or adrenal weight, irregular noise decreased body weight gain and induced a moderate adrenal hypertrophy. In addition, previous daily exposure to regular but not to irregular noise reduced both prolactin and corticosterone responses to acute noise. In contrast, glucose response to acute noise was reduced after both regular and irregular exposure to chronic noise. Either regular or irregular exposure to chronic IMO decreased food intake and body weight and increased adrenal weight to the same extent. Likewise, no influence of regularity of exposure to chronic IMO on corticosterone and prolactin responses to acute IMO was observed. However, habituation of the ACTH response to acute IMO was observed in rats subjected to chronic regular IMO, but not in rats subjected to chronic irregular IMO. Finally, acute IMO-induced hyperglycemia diminished to the same extent after regular and irregular IMO. From these results we can conclude that: first, the process of habituation of the PA axis to chronic stress is greatly dependent upon factors such as regularity of exposure to the stressor and stressor intensity, and second, the influence of regularity on the pattern of habituation to a repeated stressor is dependent on the physiological variable we are dealing with.
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The effect of water restriction on the pituitary-gonadal axis has been studied in adult male rats. Water restriction did not modify FSH, LH and testosterone levels. However, both LH and testosterone responses to acute noise stress were... more
The effect of water restriction on the pituitary-gonadal axis has been studied in adult male rats. Water restriction did not modify FSH, LH and testosterone levels. However, both LH and testosterone responses to acute noise stress were impaired by water restriction. It was unlikely that the inhibition of the pituitary-gonadal response to stress was due to an alteration of the circadian pattern of LH since no evidence for such a daily rhythm was found in either of the two experimental groups. The effects of water restriction on the pituitary-gonadal axis appear to be at least partially a consequence of the resulting reduction in food intake, so that the pituitary-gonadal response to stress would be a more sensitive index of abnormalities induced by protein-calorie deficit than basal concentrations of LH, FSH, or T.
Research Interests: Andrology, Circadian Rhythms, Stress, Circadian Rhythm, Animals, and 15 moreMale, Endocrine, Food intake, Clinical Sciences, Rats, Rat, Body Weight, Luteinizing Hormone, Follicle stimulating hormone, Gonads, Secretion, Acute stress, Experimental Group, Paediatrics and reproductive medicine, and Male rat
Post-traumatic stress disorder (PTSD) occurs after exposure to traumatic situations and it is characterized by cognitive deficits that include impaired explicit memory. The neurobiological bases of such PTSD-associated memory alterations... more
Post-traumatic stress disorder (PTSD) occurs after exposure to traumatic situations and it is characterized by cognitive deficits that include impaired explicit memory. The neurobiological bases of such PTSD-associated memory alterations are yet to be elucidated and no satisfactory treatment for them exists. To address this issue, we first studied whether a single exposure of young adult rats (60 days) to immobilization on boards (IMO), a putative model of PTSD, produces long-term behavioral effects (2-8 days) similar to those found in PTSD patients. Subsequently, we investigated whether the administration of the TrkB agonist 7,8-dihydroxyflavone (DHF) 8 hours after stress (therapeutic window) ameliorated the PTSD-like effect of IMO and the associated changes in synaptic plasticity. A single IMO exposure induced a spatial memory impairment similar to that found in other animal models of PTSD or in PTSD patients. IMO also increased spine density and long-term potentiation (LTP) in the CA3-CA1 pathway. Significantly, DHF reverted both spatial memory impairment and the increase in LTP, while it produced no effect in the controls. These data provide novel insights into the possible neurobiological substrate for explicit memory impairment in PTSD patients, supporting the idea that the activation of the BDNF/TrkB pathway fulfils a protective role after severe stress. Administration of DHF in the aftermath of a traumatic experience might be relevant to prevent its long-term consequences. This article is protected by copyright. All rights reserved.
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Research Interests: Animal Behavior, Behavior, Adaptation, Stress, Evidence-Based Practice (Psychology), and 15 moreDissociation, Habituation, Animals, Corticosterone, Male, HPA axis, Exposure, Rats, Adrenocorticotropic Hormone, Exploratory Behavior, Immobilization, Likelihood Functions, Psychological Stress, Psychology and Cognitive Sciences, and Medical and Health Sciences
The WHO has qualified stress as a 'world epidemic' due to its increasingly greater incidence on health. The work described in this paper represents an attempt to objectively quantify the level of stress. The aim of the method... more
The WHO has qualified stress as a 'world epidemic' due to its increasingly greater incidence on health. The work described in this paper represents an attempt to objectively quantify the level of stress. The aim of the method developed here is to measure how close or how far a subject is from a situation that can be considered 'normal' in medical and social terms. The literature on the pathophysiology of stress and its methods of study in experiments on both animals and humans was reviewed. Nine prospective observational studies were undertaken with different types of subjects and stressors covering the different types of stress. The results of the literature review made it possible to identify the different types of stress, the indicators that yield significant results, the psychometric tests and the well-documented 'stressors'. This material was then used to design the general method and the details of the nine clinical trials. The preliminary results obtai...