Journal of the autonomic nervous system, Dec 1, 1987
The present study was initiated to address the current controversy concerning the parasympathetic... more The present study was initiated to address the current controversy concerning the parasympathetic innervation of the pancreas, using a more sensitive tracer. The location of retrogradely labeled neurons within the dorsal motor nucleus of the vagus (DMV) was examined 48 h following injections of cholera toxin-horseradish peroxidase (CT-HRP) into designated areas of the rat pancreas. The brainstem and spinal cord were searched for any additional labeled neurons located outside of the DMV. Separate groups of animals were used for control injections into the adipose tissue of the greater omentum, the spleen, abdominal musculature, and the diaphragm. In addition, CT-HRP was dripped over the surfaces of the abdominal viscera in another group of animals. These control cases were designed to indicate whether diffusion of the neural tracer away from injection sites had occurred and had resulted in labeling of neurons which did not innervate the injected areas. Following injection of CT-HRP into the right lobe of the pancreas, labeled neurons were found primarily within the medial region of the left DMV. Injection of CT-HRP into the left lobe of the pancreas resulted in retrogradely labeled neurons predominantly within the medial region of the right DMV. Following injections into the entire pancreas, neural labeling was seen bilaterally within the DMV and was concentrated within the medial regions, with a slightly higher degree of labeling within the right DMV. No labeled neurons were seen within the nucleus ambiguus or other areas of the brainstem or spinal cord following pancreatic injections. Furthermore, no afferent labeling within the nucleus of the solitary tract (NTS) was observed, although a very small number of neurons within the nodose ganglia were labeled. The dendrites of backfilled DMV neurons could be seen extending across the midline to the contralateral DMV as well as dorsally into certain subnuclei of the NTS, and to the borders of the area postrema and the fourth ventricle. These results indicate that both the motor and sensory innervation of the rat pancreas are more restricted than has been previously suggested.
Background: The extent to which the vagus nerve innervates the colon remains controversial. Metho... more Background: The extent to which the vagus nerve innervates the colon remains controversial. Methods: In 29 rats the tracer cholera toxin-horseradish peroxidase was injected into the cecum, the ascending, transverse, or descending colon or the rectum. For comparison, control injections were made into the stomach. Results: For all areas of colon except the rectum, brainstem motoneuronal labeling was limited to the lateral third of the dorsal motor nucleus of the vagus nerve bilaterally. In contrast, gastric injections resulted in motoneuronal labeling limited to the medial portions of the nucleus. The number of labeled motoneurons was greatest following injection of the cecum, and it significantly decreased for the more distal areas of the colon. Colonic motoneuron dendrites projected into the nucleus of the solitary tract and within the dorsal motor nucleus of the vagus nerve. Sensory afferent terminal labeling was limited to the commissural and medial subnuclei of the nucleus of the solitary tract. For the rectum, sensory and motor labeling was limited to the spinal cord. Conclusions: The distribution of labeling within the vagal complex indicates that all regions of the colon, except the rectum, are innervated by the celiac and accessory celiac branches of the vagus nerve.
During the past decade it has been recognized that several structures in the anterior wall of the... more During the past decade it has been recognized that several structures in the anterior wall of the third ventricle (A3V) are involved in the regulation of water intake. With regard to these structures, the subfornical organ (SFO) is a probable receptor site for angiotensin to induce water drinking1, while ablation of the organum vasculosum of the lamina terminalis (OVLT) and the antero-ventral third ventricle wall region (AV3V) disrupts osmoregulatory water intake2,3. Destruction of the preoptic medianus nucleus (PMN) also reduces water drinking in rats4 while in goats ablation of most of the A3V results in adipsia5. In view of the likelihood that most of the A3V is involved in the regulation of thirst, we decided to study the effects of either individual or combined ablation of some of these regions in the sheep. The anterior commissure (AC), which courses horizontally across the A3V, provides a convenient boundary for division of the A3V into dorsal and ventral regions. The antero-dorsal wall of the third ventricle (AD3V) contains the SFO, dorsal part of the PMN, and the medial septum, while the anteroventral wall of the third ventricle (AV3V) encompasses the ventral PMN, the OVLT and preoptic periventricular tissue (Figure 1).
Previous light microscopic work in the rat has demonstrated that many dendrites of vagal gastric ... more Previous light microscopic work in the rat has demonstrated that many dendrites of vagal gastric motoneurons extend beyond the cytoarchitectural boundaries of the dorsal motor nucleus of the vagus (DMV) into the nucleus of the solitary tract (NST), where they overlap with the central terminal field of vagal gastric primary sensory neurons (Shapiro and Miselis, 1985a). In the present ultrastructural study, the synaptic relationship of vagal afferent terminals and vagal motor neurons and dendrites was examined. Following injection of cholera toxin-HRP conjugate (CT-HRP) into the dorsal and ventral musculature of the stomach wall, centrally transported tracer was visualized using tetramethylbenzidine or diaminobenzidine histochemistry. Light microscopy confirmed the presence of retrogradely labeled gastric DMV neurons whose dendrites extended into the overlying NST. The subnucleus gelatinosus of the dorsomedial NST at a level just rostral to the obex contained the highest density of va...
Truisms are, of course, self evident. In spite of their obviousness we need to reconsider some in... more Truisms are, of course, self evident. In spite of their obviousness we need to reconsider some in order to appreciate understanding that we take for granted and to remind ourselves of the value of particular approaches we use in our research on brain function. It seems evident to me that understanding behavior and higher order brain function reduces to knowing the rules governing the flow of information in neural networks. Biochemical, molecular, cellular and pharmocological events affect brain function by rising to modulate this flow of infomation in neural circuits. Given these axioms it is, therefore, important to learn the organization of the brain’s neural networks.
There are several anatomically and functionally distinct retinofugal pathways, one of which is th... more There are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT-HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT-HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri-SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, a light projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.
The Physiology of Thirst and Sodium Appetite, 1986
Lesions which remove the area postrema (AP) and the subjacent portions of the nucleus of the soli... more Lesions which remove the area postrema (AP) and the subjacent portions of the nucleus of the solitary tract (cmNTS) which lie in the caudal brainstem close to the dorsal spinomedullary junction cause dramatic and apparently permanent alterations in energy and fluid balance1,2. There is a well characterized syndrome of transient hypophagia and accompanying weight loss. Two to three weeks into this syndrome normophagia resumes with eventual stabilization of body weight but at a lower level. In addition there is a mild hyperdipsia. See figure 1.
Feeding was induced with lateral intracerebroventricular (ICV) injections of 2-deoxy-D-glucose (2... more Feeding was induced with lateral intracerebroventricular (ICV) injections of 2-deoxy-D-glucose (2-dg), a glucose analogue causing glucoprivation. Feeding increased rapidly by an average of 2.6 g following ICV 2-DG (2.9 or 5.8 mg per rat), but did not increase after ICV D-glucose or sucrose. At the same doses, 2-DG did not increase feeding when given peripherally. Core temperature dropped in a dose-dependent manner with doses of 2-DG sufficient to induce feeding after peripheral administration, but did not occur with ICV injections. The 2-DG (0.006--1.219 M) did not stimulate feeding when infused bilaterally into the lateral hypothalamus, the preoptic area, or the anterior lateral hypothalamus. Nor did it produce feeding when injected into the ventromedial hypothalamus at the same sites and in the same rats in which procaine HC1 caused increased feeding. The brain, therefore, is directly sensitive to glucoprivation in the control of feeding, and glucoprivation alone is sufficient to mobilize feeding behavior. The specific site of sensitivity to glucoprivation and the mode of action of the glucoprivic system in the brain are unknown.
Journal of the autonomic nervous system, Dec 1, 1987
The present study was initiated to address the current controversy concerning the parasympathetic... more The present study was initiated to address the current controversy concerning the parasympathetic innervation of the pancreas, using a more sensitive tracer. The location of retrogradely labeled neurons within the dorsal motor nucleus of the vagus (DMV) was examined 48 h following injections of cholera toxin-horseradish peroxidase (CT-HRP) into designated areas of the rat pancreas. The brainstem and spinal cord were searched for any additional labeled neurons located outside of the DMV. Separate groups of animals were used for control injections into the adipose tissue of the greater omentum, the spleen, abdominal musculature, and the diaphragm. In addition, CT-HRP was dripped over the surfaces of the abdominal viscera in another group of animals. These control cases were designed to indicate whether diffusion of the neural tracer away from injection sites had occurred and had resulted in labeling of neurons which did not innervate the injected areas. Following injection of CT-HRP into the right lobe of the pancreas, labeled neurons were found primarily within the medial region of the left DMV. Injection of CT-HRP into the left lobe of the pancreas resulted in retrogradely labeled neurons predominantly within the medial region of the right DMV. Following injections into the entire pancreas, neural labeling was seen bilaterally within the DMV and was concentrated within the medial regions, with a slightly higher degree of labeling within the right DMV. No labeled neurons were seen within the nucleus ambiguus or other areas of the brainstem or spinal cord following pancreatic injections. Furthermore, no afferent labeling within the nucleus of the solitary tract (NTS) was observed, although a very small number of neurons within the nodose ganglia were labeled. The dendrites of backfilled DMV neurons could be seen extending across the midline to the contralateral DMV as well as dorsally into certain subnuclei of the NTS, and to the borders of the area postrema and the fourth ventricle. These results indicate that both the motor and sensory innervation of the rat pancreas are more restricted than has been previously suggested.
Background: The extent to which the vagus nerve innervates the colon remains controversial. Metho... more Background: The extent to which the vagus nerve innervates the colon remains controversial. Methods: In 29 rats the tracer cholera toxin-horseradish peroxidase was injected into the cecum, the ascending, transverse, or descending colon or the rectum. For comparison, control injections were made into the stomach. Results: For all areas of colon except the rectum, brainstem motoneuronal labeling was limited to the lateral third of the dorsal motor nucleus of the vagus nerve bilaterally. In contrast, gastric injections resulted in motoneuronal labeling limited to the medial portions of the nucleus. The number of labeled motoneurons was greatest following injection of the cecum, and it significantly decreased for the more distal areas of the colon. Colonic motoneuron dendrites projected into the nucleus of the solitary tract and within the dorsal motor nucleus of the vagus nerve. Sensory afferent terminal labeling was limited to the commissural and medial subnuclei of the nucleus of the solitary tract. For the rectum, sensory and motor labeling was limited to the spinal cord. Conclusions: The distribution of labeling within the vagal complex indicates that all regions of the colon, except the rectum, are innervated by the celiac and accessory celiac branches of the vagus nerve.
During the past decade it has been recognized that several structures in the anterior wall of the... more During the past decade it has been recognized that several structures in the anterior wall of the third ventricle (A3V) are involved in the regulation of water intake. With regard to these structures, the subfornical organ (SFO) is a probable receptor site for angiotensin to induce water drinking1, while ablation of the organum vasculosum of the lamina terminalis (OVLT) and the antero-ventral third ventricle wall region (AV3V) disrupts osmoregulatory water intake2,3. Destruction of the preoptic medianus nucleus (PMN) also reduces water drinking in rats4 while in goats ablation of most of the A3V results in adipsia5. In view of the likelihood that most of the A3V is involved in the regulation of thirst, we decided to study the effects of either individual or combined ablation of some of these regions in the sheep. The anterior commissure (AC), which courses horizontally across the A3V, provides a convenient boundary for division of the A3V into dorsal and ventral regions. The antero-dorsal wall of the third ventricle (AD3V) contains the SFO, dorsal part of the PMN, and the medial septum, while the anteroventral wall of the third ventricle (AV3V) encompasses the ventral PMN, the OVLT and preoptic periventricular tissue (Figure 1).
Previous light microscopic work in the rat has demonstrated that many dendrites of vagal gastric ... more Previous light microscopic work in the rat has demonstrated that many dendrites of vagal gastric motoneurons extend beyond the cytoarchitectural boundaries of the dorsal motor nucleus of the vagus (DMV) into the nucleus of the solitary tract (NST), where they overlap with the central terminal field of vagal gastric primary sensory neurons (Shapiro and Miselis, 1985a). In the present ultrastructural study, the synaptic relationship of vagal afferent terminals and vagal motor neurons and dendrites was examined. Following injection of cholera toxin-HRP conjugate (CT-HRP) into the dorsal and ventral musculature of the stomach wall, centrally transported tracer was visualized using tetramethylbenzidine or diaminobenzidine histochemistry. Light microscopy confirmed the presence of retrogradely labeled gastric DMV neurons whose dendrites extended into the overlying NST. The subnucleus gelatinosus of the dorsomedial NST at a level just rostral to the obex contained the highest density of va...
Truisms are, of course, self evident. In spite of their obviousness we need to reconsider some in... more Truisms are, of course, self evident. In spite of their obviousness we need to reconsider some in order to appreciate understanding that we take for granted and to remind ourselves of the value of particular approaches we use in our research on brain function. It seems evident to me that understanding behavior and higher order brain function reduces to knowing the rules governing the flow of information in neural networks. Biochemical, molecular, cellular and pharmocological events affect brain function by rising to modulate this flow of infomation in neural circuits. Given these axioms it is, therefore, important to learn the organization of the brain’s neural networks.
There are several anatomically and functionally distinct retinofugal pathways, one of which is th... more There are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT-HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT-HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri-SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, a light projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.
The Physiology of Thirst and Sodium Appetite, 1986
Lesions which remove the area postrema (AP) and the subjacent portions of the nucleus of the soli... more Lesions which remove the area postrema (AP) and the subjacent portions of the nucleus of the solitary tract (cmNTS) which lie in the caudal brainstem close to the dorsal spinomedullary junction cause dramatic and apparently permanent alterations in energy and fluid balance1,2. There is a well characterized syndrome of transient hypophagia and accompanying weight loss. Two to three weeks into this syndrome normophagia resumes with eventual stabilization of body weight but at a lower level. In addition there is a mild hyperdipsia. See figure 1.
Feeding was induced with lateral intracerebroventricular (ICV) injections of 2-deoxy-D-glucose (2... more Feeding was induced with lateral intracerebroventricular (ICV) injections of 2-deoxy-D-glucose (2-dg), a glucose analogue causing glucoprivation. Feeding increased rapidly by an average of 2.6 g following ICV 2-DG (2.9 or 5.8 mg per rat), but did not increase after ICV D-glucose or sucrose. At the same doses, 2-DG did not increase feeding when given peripherally. Core temperature dropped in a dose-dependent manner with doses of 2-DG sufficient to induce feeding after peripheral administration, but did not occur with ICV injections. The 2-DG (0.006--1.219 M) did not stimulate feeding when infused bilaterally into the lateral hypothalamus, the preoptic area, or the anterior lateral hypothalamus. Nor did it produce feeding when injected into the ventromedial hypothalamus at the same sites and in the same rats in which procaine HC1 caused increased feeding. The brain, therefore, is directly sensitive to glucoprivation in the control of feeding, and glucoprivation alone is sufficient to mobilize feeding behavior. The specific site of sensitivity to glucoprivation and the mode of action of the glucoprivic system in the brain are unknown.
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