New data on the immunocytochemical localization of thyrotropin-releasing hormone in the rat central nervous system

An antiserum raised against the synthetic tripeptide pyroglutamyl-histidyl-proline (free acid) was used to localize thyrotropin-releasing hormone (TRH) in the rat central nervous system (CNS) by immunocytochemistry. The distribution of TRH-immunoreactive structures was similar to that reported earlier; i.e., most of the TRH-containing perikarya were located in the parvicellular part of the hypothalamic paraventricular nucleus, the suprachiasmatic portion of the preoptic nucleus, the dorsomedial nucleus, the lateral basal hypothalamus, and the raphe nuclei. Several new locations for TRH-immunoreactive neurons were also observed, including the glomerular layer of the olfactory bulb, the anterior olfactory nuclei, the diagonal band of Broca, the septal nuclei, the sexually dimorphic nucleus of the preoptic area, the reticular thalamic nucleus, the lateral reticular nucleus of the medulla oblongata, and the central gray matter of the mesencephalon. Immunoreactive fibers were seen in the median eminence, the organum vasculosum of the lamina terminalis, the lateral septal nucleus, the medial habenula, the dorsal and ventral parabrachial nuclei, the nucleus of the solitary tract, around the motor nuclei of the cranial nerves, the dorsal vagal complex, and in the reticular formation of the brainstem. In the spinal cord, no immunoreactive perikarya were observed. Immunoreactive processes were present in the lateral funiculus of the white matter and in laminae V-X in the gray matter. Dense terminal-like structures were seen around spinal motor neurons. The distribution of TRH-immunoreactive structures in the CNS suggests that TRH functions both as a neuroendocrine regulator in the hypothalamus and as a neurotransmitter or neuromodulator throughout the CNS.     

Galanin-like immunoreactivity in the chicken brain

The anatomical distribution of neurons containing galanin has been studied in the central nervous system of the chicken by means of immunocytochemistry using antisera against rat galanin. Major populations of immunostained perikarya were detected in several brain areas. The majority of galanin-immunoreactive cell bodies was present in the hypothalamus and in the caudal brainstem. Extensive groups of labeled perikarya were found in the paraventricular, periventricular, dorsomedial and tuberal hypothalamic nuclei, and in the nucleus of the solitary tract in the medulla oblongata. In the telencephalon, immunoreactive perikarya were observed in the preoptic area, in the lateral septal nucleus and in the hippocampus. The mesencephalon contained only a few galanin-positive perikarya located in the interpeduncular nucleus. Immunoreactive nerve fibers of varying density were detected in all subdivisions of the brain. Dense accumulations of galanin-positive fibers were seen in the preoptic area, periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the central gray of the brainstem, and the dorsomedial caudal medulla. The distributional pattern of galanin-immunoreactive neurons suggests a possible involvement of a galanin-like peptide in several neuroregulatory mechanisms.     

Identification of growth-hormone- and prolactin-containing neurons within the avian brain

Prolactin (PRL)- and growth-hormone (GH)-containing perikarya and fibers independent of the anterior pituitary gland have been reported to exist in the central nervous system of several mammalian species. The specific distributions of PRL- or GH-like neurons in the avian forebrain and midbrain, however, have not been reported. The objective of the study was to identify GH- and PRL-containing neurons in the hypothalamus and a few extrahypothalamic areas of two avian species. Brain and peripheral blood samples were collected from laying and broody turkey hens and ring doves. Broody turkey hens and doves had significantly higher plasma PRL concentrations compared with laying hens. Coronal brain sections were prepared and immunostained using anti-turkey GH and anti-chicken synthetic PRL antibodies. In turkey hens, the most dense GH-immunoreactive (ir) perikarya and fibers were found in hippocampus (Hp), periventricular hypothalamic nucleus, paraventricular nucleus, inferior hypothalamic nucleus, infundibular hypothalamic nucleus, medial and lateral septal area, and external zone of the median eminence (ME). In the ring dove, a similar pattern of distribution of GH-ir neurons was noticed at the brain sites listed above except that GH-ir fibers and granules were found only in the internal zone of ME and not in the external zone. In both turkeys and doves, the most immunoreactive PRL-ir perikarya and fibers were found in the medial and lateral septal area, Hp (turkey only), and bed nucleus of the stria terminalis pars magnocellularis. There were no apparent differences in the staining pattern of GH- or PRL-ir neurons between the laying and broody states in either species. However, the presence of GH-ir- and PRL-ir perikarya and fibers in several hypothalamic nuclei indicates that GH and PRL may influence parental behavior, food intake, autonomic nervous system function, and/or reproduction.     

Vasoactive intestinal polypeptide (VIP)-containing neurons: distribution throughout the brain of the chick (Gallus domesticus) with focus upon the lateral septal organ

The distribution of VIP-like perikarya and fibers was determined throughout the chick brain. The most rostral immunoreactive perikarya were found to be cerebrospinal fluid-contacting neurons in the pars medialis of the lateral septal organ. Additional data were presented supporting the idea that the lateral septal organ is another circumventricular organ within the brain of birds (Kuenzel and van Tienhoven 1982). A large group of immunoreactive perikarya was found in the lateral hypothalamic area and appeared continuous with immunoreactive neurons in the anterior medial and ventromedial hypothalamic nuclei (n). A few perikarya were located in the paraventricular hypothalamic n. A number of immunoreactive neurons were found within and about the infundibular and inferior hypothalamic n., none however was immunoreactive cerebrospinal fluid-contacting neurons. Immunoreactive perikarya were found predominantly in laminae 10–11 of the stratum griseum et fibrosum superficiale. A few scattered perikarya were found ventromedial to the n. tegmenti pedunculo-pontinus pars compacta and locus ceruleus. Some of the immunoreactivity was unusual, being very homogeneous within the cell body with little evidence of the material in the axon or dendrites. Perikarya were found in the central gray, n. intercollicularis, and area ventralis of Tsai. The most caudal structure showing immunoreactive neurons was the n. reticularis paragigantocellularis lateralis. Brain areas containing the most abundant immunoreactive fibers, listed from the rostral-most location, were found in the ventromedial region of the lobus parolfactorius and the lateral septal n. Continuing caudally, there were immunoreactive fibers within the periventricular hypothalamic n.; some of the fibers were found to travel for some distance parallel to the third ventricle. Dense immunoreactive fibers were found in the tractus cortico-habenularis et cortico-septalis, medial habenular n. and posterior and dorsal n. of the archistriatum. A number of areas had what appeared to be baskets of immunoreactive fibers (perhaps immunoreactive terminals) surrounding non-reactive perikarya. Brain areas containing terminals included the piriform cortex, area ventralis of Tsai, interpeduncular n., and specific regions of the stratum griseum et fibrosum superficiale. A very dense immunoreactivity occurred within the external zone of the median eminence, the dorsolateral parabrachial n., and n. tractus solitarii. Vasoactive intestinal polypeptide appears to be a useful peptide for defining the neuroanatomical constituents of the visceral forebrain in birds.     

Vasoactive intestinal polypeptide (VIP)-containing neurons: distribution throughout the brain of the chick (Gallus domesticus) with focus upon the lateral septal organ

The distribution of VIP-like perikarya and fibers was determined throughout the chick brain. The most rostral immunoreactive perikarya were found to be cerebrospinal fluid-contacting neurons in the pars medialis of the lateral septal organ. Additional data were presented supporting the idea that the lateral septal organ is another circumventricular organ within the brain of birds (Kuenzel and van Tienhoven 1982). A large group of immunoreactive perikarya was found in the lateral hypothalamic area and appeared continuous with immunoreactive neurons in the anterior medial and ventromedial hypothalamic nuclei (n). A few perikarya were located in the paraventricular hypothalamic n. A number of immunoreactive neurons were found within and about the infundibular and inferior hypothalamic n., none however was immunoreactive cerebrospinal fluid-contacting neurons. Immunoreactive perikarya were found predominantly in laminae 10–11 of the stratum griseum et fibrosum superficiale. A few scattered perikarya were found ventromedial to the n. tegmenti pedunculo-pontinus pars compacta and locus ceruleus. Some of the immunoreactivity was unusual, being very homogeneous within the cell body with little evidence of the material in the axon or dendrites. Perikarya were found in the central gray, n. intercollicularis, and area ventralis of Tsai. The most caudal structure showing immunoreactive neurons was the n. reticularis paragigantocellularis lateralis. Brain areas containing the most abundant immunoreactive fibers, listed from the rostral-most location, were found in the ventromedial region of the lobus parolfactorius and the lateral septal n. Continuing caudally, there were immunoreactive fibers within the periventricular hypothalamic n.; some of the fibers were found to travel for some distance parallel to the third ventricle. Dense immunoreactive fibers were found in the tractus cortico-habenularis et cortico-septalis, medial habenular n. and posterior and dorsal n. of the archistriatum. A number of areas had what appeared to be baskets of immunoreactive fibers (perhaps immunoreactive terminals) surrounding non-reactive perikarya. Brain areas containing terminals included the piriform cortex, area ventralis of Tsai, interpeduncular n., and specific regions of the stratum griseum et fibrosum superficiale. A very dense immunoreactivity occurred within the external zone of the median eminence, the dorsolateral parabrachial n., and n. tractus solitarii. Vasoactive intestinal polypeptide appears to be a useful peptide for defining the neuroanatomical constituents of the visceral forebrain in birds.     

The distribution of corticotropin-releasing factor-immunoreactive neurons and nerve fibers in the brain of the snake,Natrix maura

Summary The anatomical distribution of neurons and nerve fibers containing corticotropin-releasing factor (CRF) has been studied in the brain of the snake, Natrix maura, by means of immunocytochemistry using an antiserum against rat CRF. To test the possible coexistence of CRF with the neurohypophysial peptides arginine vasotocin (AVT) and mesotocin (MST) adjacent sections were stained with antisera against the two latter peptides. CRF-immunoreactive (CRF-IR) neurons exist in the paraventricular nucleus (PVN). In some neurons of the PVN, coexistence of CRF with MST or of CRF with AVT has been shown. Numerous CRF-IR fibers run along the hypothalamo-hypophysial tract and end in the outer layer of the median eminence. In addition, some fibers reach the neural lobe of the hypophysis. CRF-IR perikarya have also been identified in the following locations: dorsal cortex, nucleus accumbens, amygdala, subfornical organ, lamina terminalis, nucleus of the paraventricular organ, nucleus of the oculomotor nerve, nucleus of the trigeminal nerve, and reticular formation. In addition to all these locations CRF-IR fibers were also observed in the lateral septum, supraoptic nucleus, habenula, lateral forebrain bundle, paraventricular organ, hypothalamic ventromedial nucleus, raphe and interpeduncular nuclei.     

Glucagon-related peptides in the rat hypothalamus

Summary Immunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism.     

Immunoreactivity to vasoactive intestinal polypeptide (VIP) and thyreotropin-releasing hormone (TRH) in hypothalamic neurons of the domesticated pigeon (Columba livia). Alterations following lactation and exposure to cold

Summary The distribution of VIP- and TRH-immunoreactivity in neurons and processes within the hypothalamus of the pigeon was investigated with light-microscopic immunocytochemical techniques. Most of the VIP-containing neurons are concentrated in the middle and caudal parts of the hypothalamus, with the greatest concentration of perikarya occurring in the medial and lateral part of the ventromedial hypothalamic nucleus and the infundibular nucleus. These cells give rise to axons that seem to extend into the median eminence. An extensive network of VIP-immunoreactive fibers and varicosities occupy the external layer of the median eminence. The majority of TRH-containing neurons is found in the anterior hypothalamus with the greatest concentration of cells in the magnocellular preoptic, medial preoptic, suprachiasmatic and paraventricular nuclei. TRH-immunoreactive fibers and varicosities form a dense arborization in the external layer of the median eminence. Lactation seems to induce substantial changes in VIP as well as in TRH-immunostaining in the median eminence and other hypothalamic regions as compared to control, sexually active animals. Furthermore, TRH-immunoreactivity decreased in the median eminence following 60-min exposure to cold. These results suggest that VIP- and TRH-containing pathways in the pigeon hypothalamus are involved in the mediation of neuroendocrine responses.     

Corticotropin-releasing hormone-like immunoreactivity in the brain of the snake Bothrops jararaca

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.     

Distribution of gastrin and CCK-like peptides in rat brain

Summary The distribution of gastrin and CCK-like peptides in the rat brain was studied by immunocytochemistry using an antiserum reacting equally well with both groups of peptides. Immunoreactive nerve cell bodies were detected in all cortical areas, in the hippocampus where they were particularly numerous, in the mesencephalic central gray and in the medulla oblongata. After colchicine treatment immunoreactive material appeared also in cell bodies of the magnocellular hypothalamic system. Immunoreactive nerve fibers were widely distributed in the brain. Particularly dense accumulations were seen in the hippocampus near the ventral surface of the brain, in the caudate nucleus, in the interpeduncular nucleus, the parabrachial nucleus, the dorsal part of the medulla oblongata and in the dorsal horn of the spinal cord. In the hypothalamus immunoreactive nerve fibers were observed in all nuclei, being most frequent in the ventromedial, dorsal and lateral hypothalamic nuclei. A rich supply of nerve fibers was seen in the outer zone of the median eminence and in the neurohypophysis. From previous immunochemical analysis it appears that the peptide demonstrated in most parts of the brain is identical with CCK-8. In the neurosecretory cell bodies of the hypothalamus, the median eminence and the neurohypophysis, however, the immunoreactive material is probably identical with gastrin.     

Immimohistochemical localization of corticotropin-releasing factor in selected brain areas of the European starling (Sturnus vulgaris) and the song sparrow (Melospiza melodia)

Summary Corticotropin-releasing factor (CRF) was localized in the brains of two passerine species, the European starling (Sturnus vulgaris) and the song sparrow (Melospiza melodia), by means of immunohistochemistry. The hypothalamic distribution of this peptide in these species includes a complex of immunoreactive perikarya observed in the paraventricular nucleus (PVN), in both its medial and lateral divisions. Nerve fibers were also seen running from these areas to the anterior median eminence (AME) where a terminal field is apparent. A wide variety of extra-hypothalamic nuclei containing CRF-immunoreactive cells and fibers were identified. An apparent CRF terminal field can be visualized in the lateral septum. A dense fiber plexus is present in the nucleus accumbens (Ac) and more caudally in the nucleus of the stria terminalis (nST). In colchicinepretreated animals, it was revealed that these areas also contain CRF-stained perikarya. The pattern of CRF immunoreactivity in the Ac-nST complex is continuous, with no distinction apparent between the nuclei. The medial preoptic area (mPOA) and the adjacent diagonal band of Broca contain CRF-fibers, while cells are apparent in the mPOA. In the mesencephalon, cells were visualized in the midbrain central gray; a terminal field and scattered positively stained perikarya were found in areas more ventral to the central grey that are adjacent to the third cranial nerve. Scattered cells were also seen at the border of the nucleus intercollicularis-nucleus mesencephalicus lateralis, pars dorsalis complex. In contrast to mammalian studies, no immunoreactive nerve fibers or perikarya were observed in telencephalic areas homologous to the mammalian neocortex. These studies confirm the presence of a CRF path-way regulating pituitary function and suggest a broad role played by CRF as a neuromodulator or neurotransmitter in autonomic and possibly behavioral activities in these species.     

Ontogenetic development of thyrotropin-releasing hormone (TRH)-immunoreactive structures in the brain of the mallard embryo

Summary Developmental changes of thyrotropin-releasing hormone (TRH)-immunoreactive structures in the brain of mallard embryos were studied by means of immunocytochemistry (PAP technique). The primary antibody was generated against synthetic TRH. Immunoreactive neurons were first detected in the hypothalamus of 14-day-old embryos. By day 20, increasing numbers of immunoreactive perikarya were observed in the paraventricular nucleus, anterior preoptic region and supraoptic region. Immunoreactive fiber projections were seen in the median eminence as early as embryonic day 20; they occurred also in some extrahypothalamic regions (lateral septum, accumbens nucleus). The number and staining intensity of the cell bodies increased up to hatching, and continued to increase during the first week after hatching.     

Immunoreactive material resembling ovine prolactin in perikarya and nerve terminals of the rat hypothalamus

Summary The presence of prolactin (PRL)-like material is demonstrated in the brain of rats with the aid of anti-ovine PRL (oPRL) IgG as primary antibody in the unlabeled antibody-enzyme method. Immunoreactive deposits are visualized as an intraneuronal constituent with a widespread distribution in the hypothalamus and neural lobe of the pituitary. Dense networks of reactive nerve terminals derived from two prominent fibre tracts, a ventral (VHT) and a dorsal hypothalamo-neurohypophysial tract (DHT) are seen. The VHT is confined to the median eminence and pars oralis tuberis, the DHT to the pars caudalis tuberis. Both fibre tracts pass through the infundibular stalk into the neural lobe. The origin of the immunoreactive nerve terminals can be elucidated only to some extent. The VHT gives off beaded fibres entering the ependymal and glandular layer of the median eminence. Immunoreactive perikarya are observed in the supraoptic nucleus, the paraventricular nucleus, the anterior hypothalamic nucleus, the anterior commissural nucleus, the preoptic nucleus and the interstitial nucleus of the stria terminalis. A few of the immunoreactive perikarya are observed in close connection with brain vessels and the ependymal cells of the third ventricle. The results indicate that the anti-oPRL has a unique region specificity implying that only a segment of the mammalian PRL molecule is present in these nuclei of the brain. Fragments of PRL may function as neuromodulators or neurotransmitters in the rat brain.We are indebted to Dr. Mogens Hammer, Rigshospitalet, Copenhagen for the gift of Arg-VP and anti-VP, and to NIAMDD for the gift of ovine PRL, ratPRL, anti-rPRL, anti-hPRL and bovineSTH     

Monoamine fluorescence in the median eminence of the Japanese quail,Coturnix coturnix japonica,following medial basal hypothalamic deafferentation

Summary Monoamine fluorescence was examined in the ventral hypothalamus of the Japanese quail, Coturnix coturnix japonica after medial basal hypothalamic deafferentation. In sham-operated control birds, numerous yellow-green fluorescent fibers were observed in the median eminence and the nucleus tuberis. In the area of the paraventricular organ, a number of fluorescent fibers and cell bodies were observed. In birds with deafferented hypothalami, fluorescence disappeared both in the median eminence and the nucleus tuberis. In the area of the paraventricular organ, which was within the area of deafferentation, fluorescence of neuronal perikarya did not change, but fluorescent fibers decreased markedly in number. Disappearance of monoamine fluorescence in the median eminence and the nucleus tuberis is discussed in relation to the tanycyte absorptive function and gonadal development.Supported by Grants from the Ministry of Education to Professors T. Bando and H. Kobayashi, and a Grant from the Ford Foundation to Prof. H. Kobayashi.     

The somatostatin system of the brain and hibernation in the European hamster (Cricetus cricetus)

The depression of physiological processes characteristic of mammalian hibernation is precisely regulated by the central nervous system, especially by the neuropeptidergic apparatus of the hypothalamus. Because of inhibitory influences on neuronal circuits within the brain and suppressive effects on the metabolism via the endocrine axis, somatostatin has been implicated in the regulation of hibernation. The somatostatin system of the brain was investigated with immunocytochemistry, in situ hybridization, and radioimmunoassays in euthermic summer, euthermic winter, and hibernating European hamsters (Cricetus cricetus). Numerous somatostatin-immunoreactive perikarya were observed in the periventricular hypothalamic nucleus. The striatum, amygdala, and cortex contained only scattered immunoreactive perikarya. These entities also contained immunoreactive fiber profiles, although the highest density of immunoreactive fibers was found in the median eminence. Immunocytochemistry and radioimmunoassays showed that the number of somatostatin-immunoreactive perikarya and fibers and the content of somatostatin in the hypothalamus and the median eminence was conspicuously lower in euthermic winter animals than in euthermic summer animals. This decrease was more pronounced in hibernating specimens. In situ hybridization also demonstrated a decrease in the expression and synthesis rate of somatostatin in euthermic winter animals; again, this was even more dramatic in hibernating hamsters. These changes were less pronounced or non-significant in the extrahypothalamic somatostatin-immunoreactive perikarya and fiber systems, as shown by immunocytochemistry and radioimmunoassay, respectively.     

Expression of corticosteroid-binding protein in the human hypothalamus, co-localization with oxytocin and vasopressin.

Corticosteroid-binding globulin, a specific steroid carrier in serum with high binding affinity for glucocorticoids, is expressed in various tissues. In the present study, we describe the immunocytochemical distribution of this protein in neurons and nerve fibers in the human hypothalamus. CBG immunoreactive perikarya and fibers were observed in the paraventricular, supraoptic, and sexual dimorphic nuclei in the perifornical region, as well as in the lateral hypothalamic and medial preoptic areas, the region of the diagonal band, suprachiasmatic and ventromedial nuclei, bed nucleus of the stria terminalis and some epithelial cells from the choroid plexus and ependymal cells. Stained fibers occurred in the median eminence and infundibulum. Double immunostaining revealed a partial co-localization of corticosteroid-binding globulin with oxytocin and, to a lesser extent, with vasopressin in the paraventricular and the supraoptic nuclei. Double immunofluorescence staining showed coexistence of these substances in axonal varicosities in the median eminence. We conclude that neurons of the human hypothalamus are capable of expressing corticosteroid-binding globulin, in part co-localized with the classical neurohypophyseal hormones. The distribution of CBG immunoreactive neurons, which is widespread but limited to specific nuclei, indicates that CBG has many physiological functions that may include neuroendocrine regulation and stress response.     

Immunocytochemical investigation of the hypothalamo-neurohypophysial system in birds

Summary The results of an immunohistochemical investigation of the hypothalamo-neurohypophysial system in several species of birds have shown that: (1) mesotocin and vasotocin are synthesized in separate neurons; (2) in all species investigated the distribution of mesotocinergic and vasotocinergic perikarya follows a common pattern; (3) the external zone of the avian anterior median eminence contains exclusively vasotocinergic nerve fibers, originating in supraoptic and ventral paraventricular regions; (4) the distribution of immunoreactive elements in the neural lobe shows a definite species-dependent pattern.     

Neuropeptide Y localization in telencephalic and diencephalic structures of the ground squirrel brain

The distribution of neuropeptide Y-immunoreactive (NPY-IR) perikarya, fibers, and terminals was investigated in the brain of two species of hibernatory ground squirrels, Spermophilus tridecemlineatus and S. richardsonii, by means of immunohistochemistry. In the telencephalic and diencephalic structures studied, distinct patterns of NPY-IR were observed which were essentially identical in male and female animals of both species. No differences in amount or distribution of NPY-IR structures were observed between animals which had been in induced hibernation for several months before sacrifice in March/April and those sacrificed one week after their capture in May. In some brain structures (e.g., the hypothalamic arcuate nucleus), IR cell bodies were observed only after pretreatment with colchicine. NPY-IR perikarya and fibers were found in the cerebral cortex, caudate nucleus-putamen, and dorsal part of the lateral septal nucleus. Dense fiber plexuses were seen in the lateral and medial parts of the bed nucleus of the stria terminalis. The numbers of IR perikarya observed in the medial part of the nucleus increased following intraventricular colchicine injections. The accumbens nucleus exhibited few IR cells and many fibers. Claustrum and endopiriform nuclei showed a considerable number of stained cells and fibers that increased in number and staining intensity in colchicine-treated ground squirrels. The induseum griseum showed a small band of IR cell bodies and varicose fibers. Bipolar of multipolar IR cells and varicose fibers were found in the basal nucleus of the amygdala. Dense fiber plexuses as well as IR terminals were seen in the median, medial, and lateral preoptic areas of the hypothalamus. Terminals and relatively few fibers were located in the periventricular, paraventricular, and supraoptic nuclei. The anterior, lateral, dorsomedial, and ventromedial hypothalamic nuclei contained relatively large numbers of terminals and fibers. In the suprachiasmatic nuclei, dense terminals were distributed mainly in the ventromedial subdivision. In the median eminence, immunoreactive terminals were concentrated in the external layer, with fibers predominant in the internal layer. NPY-IR perikarya were observed only in the arcuate nucleus of the hypothalamus and only following colchicine treatment. In the epithalamus (superficial part of the pineal gland and habenular nuclei), varicose fibers appeared mainly in perivascular locations (pineal) or as a dense plexus (habenular nuclei). These results from ground squirrels are discussed in comparison to those obtained in other species and with regard to considerations of the physiological role of NPY.     

Immunocytochemical demonstration of somatostatin-containing neurons in the hypothalamus of the domestic mallard

Summary In the hypothalamus of the adult domestic mallard, small to medium-sized perikarya are stained specifically with rabbit antiserum against cyclic somatostatin (PAP technique of Sternberger). The somatostatin-immunoreactive material is located in neurons different from those containing immunoreactive LHRH, vasotocin or mesotocin. Somatostatin-containing perikarya are observed 1) in a chain-like arrangement extending from the area of the median division of the supraoptic nucleus to the caudal end of the paraventricular nucleus; 2) as single cells in the preoptic region; and 3) as a conspicuous formation in the optic tract division of the supraoptic nucleus. In the rostral portion of the median eminence, somatostatin-immunoreactive axons penetrate into the external zone. Fine accessory fiber bundles project to the neural lobe.     

The corticotropin releasing factor (CRF) neurosecretory system in intact, adrenalectomized, and adrenalectomized-dexamethasone treated rats. An immunocytochemical analysis

In general, antisera generated against ovine CFR do not reveal immunopositive neuronal perikarya in the rat. If animals are adrenalectomized significant amounts of immunoreactive CFR are present in the hypothalamus. By using this model, we have visualized the CFR system of the rat. Intact, intact pretreated with dexamethasone, adrenalectomized, and adrenalectomized pretreated with dexamethasone animals were used in the present study. In adrenalectomized and adrenalectomized plus dexamethasone treated animals the CFR-immunopositive neurons were observed in the parvocellular portion of the paraventricular nucleus. Distinct pathways of CRF fibers could be seen emerging from this hypothalamic nucleus. The greatest number of these fibers exited the PVN laterally and crossed either superior to or beneath the fibers of the fornix. The fibers then turned ventrally and cascaded to form a bundle of fibers above the superio-lateral margin of the optic chiasm. They turned caudally and followed the optic tract. As these fibers reached the level of the anterior median eminence, they turned medially to run along the inferior margin of the hypothalamus and enter the median eminence. A few fibers emerged from the PVN along the periventricular margin of the third ventricle, traveled caudally in the periventricular nucleus and entered the median eminence. Adrenalectomized and adrenalectomized-dexamethasone treated rats had very dense accumulations of immunoreactive CRF in the median eminence when compared with controls. Immunoreactive neurons and fibers were also observed in the central nucleus of the amygdala in the adrenalectomized and adrenalectomized-dexamethasone treated animals.