Efferent ACTH-IR opiocortin projections from nucleus tractus solitarius: a hypothalamic deafferentation study

The distribution of opiocortin (OR-ir) immunoreactive fibers was examined immunocytochemically throughout the brain in rats following surgical isolation of the arcuate opiocortin-ir neuronal pool in the medial basal hypothalamus (MBH). Fibers which emanate from this pool were completely severed and thus eliminated from the rest of the brain, leaving intact those which can be identified immunocytochemically as opiocortin-ir projections from the medullary pool located in the nucleus tractus solitarius (NTS). These studies reveal a unique organizational pattern of proopiomelanocortin (POMC) peptidergic neuronal systems and demonstrate that several pontine and medullary regions receive projections from both the hypothalamic (arcuate) and medullary (NTS) opiocortin-ir perikarya. Comparative analyses of deafferented and control brains reveal that certain brainstem autonomic centers such as parabrachial (PB), locus coeruleus (LC), nucleus paragiganticellularis (PGi) are recipients of fibers which emanate from both arcuate and NTS opiocortin-ir perikarya. Areas which receive projections from arcuate opiocortin-ir neurons alone include forebrain and hypothalamic nuclei as well as the periaqueductal grey.     

Immunocytochemical demonstration of GAP-like immunoreactive neuronal elements in the human hypothalamus and pituitary

GnRH-associated peptide (GAP)-like immunonreactive elements located in the human hypothalamus were investigated by PAP immunocytochemistry using specific antiserum against [pro-GnRH (14-69) OH]. Immunoreactive neuronal perikarya were distributed in the MPOA, PVN and infundibular nucleus, with the largest numbers of GAP-like immunoreactive perikarya found in the infundibular nucleus. We also detected the coexistence of GAP-like and GnRH-like immunoreactivities in the same neuronal perikarya in the MPOA by using a double immunolabelling procedure. In addition to the above regions immunoreactive neuronal perikarya were present in the region dorsal to the medial mammillary nucleus. GAP-like immunoreactive fibers were distributed in same areas that immunoreactive perikarya were observed. Many immunoreactive terminals were found adjacent to capillaries in the infundibulum. Immunoreactive dots, presumably terminals, were observed in the posterior pituitary and these were particularly evident along the margin adjacent to the anterior pituitary. The distribution pattern and density of GAP-like immunoreactive neuronal elements are compared with those of other mammalian species. We also compared GAP-like immunoreactive elements with that of GnRH as has been previously observed in the human hypothalamus.     

Immunocytochemical demonstration of GAP-like immunoreactive neuronal elements in the human hypothalamus and pituitary

Summary GnRH-associated peptide (GAP)-like immunoreactive elements located in the human hypothalamus were investigated by PAP immunocytochemistry using specific antiserum against [pro-GnRH (14–69) OH]. Immunoreactive neuronal perikarya were distributed in the MPOA, PVN and infundibular nucleus, with the largest numbers of GAP-like immunoreactive perikarya found in the infundibular nucleus. We also detected the coexistence of GAP-like and GnRH-like immunoreactivities in the same neuronal perikarya in the MPOA by using a double immunolabelling procedure. In addition to the above regions immunoreactive neuronal perikarya were present in the region dorsal to the medial mammillary nucleus. GAP-like immunoreactive fibers were distributed in same areas that immunoreactive perikarya were observed. Many immunoreactive terminals were found adjacent to capillaries in the infundibulum. Immunoreactive dots, presumably terminals, were observed in the posterior pituitary and these were particularly evident along the margin adjacent to the anterior pituitary. The distribution pattern and density of GAP-like immunoreactive neuronal elements are compared with those of other mammalian species. We also compared GAP-like immunoreactive elements with that of GnRH as has been previously observed in the human hypothalamus.     

Immunohistochemical localization of the luteinizing hormone releasing hormone (LHRH)-containing structures in the central nervous system of the domestic fowl

Summary The location of LHRH-containing neuronal elements was investigated in the domestic fowl by means of immunohistochemical techniques. LHRH antisera were raised against synthetic LHRH in the rabbit. The antiserum used in the present study cross-reacted with LHRH of mammalian and avian tissues.LHRH-immunoreactive perikarya are located in the preoptic and in the septal areas, and in the bulbus olfactorius; however, no LHRH-immuno-reactive perikarya were found in the tuberal part of the hypothalamus. LHRH-immunoreactive fibers course from these areas toward the median eminence mainly along the wall of the third ventricle in the form of a periventricular network. Originating from the same cell groups other fibers run caudally immediately above the optic chiasma, forming the median bundle of the tractus preoptico-infundibularis. The third bundle running toward the OVLT is named the tractus preoptico-terminalis. In addition to these structures, LHRH-containing fibers and terminals were also present in different regions of the limbic system, in the dorsal part of the hippocampus, in the tuberculum and bulbus olfactorius, as well as in the optic lobe, nuclei commissurales tectales, organon subcommissurale, periaqueductal area, and pars ventralis mesencephali.The general distribution of the LHRH system in the chicken corresponds principally to that described previously in rodents (Sétáló et al. 1976, 1978). However, some subtle differences were demonstrated between the location of the LHRH system in birds and mammals.     

Distribution of immunoreactive somatostatin in the primate hypothalamus

Immunocytochemical methods were used to compare the localization of somatostatin (SRIF) in the human and rhesus monkey hypothalamus. The distribution of SRIF-containing cell bodies and fibers is similar in the two species. Perikarya are located predominantly in the periventricular region and to a lesser extent in the ventromedial nucleus. Fibers occur in dense clusters within the periventricular region, ventromedial nucleus, arcuate nucleus, median eminence, and pericommissural area of both species. Analysis of serial sections suggests that fibers originate from cells in the periventricular region, extend ventrally through the ventromedial and arcuate nuclei to terminate around the portal vessels of the infundibular stalk, and thereby participate in the regulation of anterior pituitary function. Somatostatinergic fibers are also found surrounding non-immunoreactive perikarya in the ventromedial nucleus and periventricular region of both primates. This arrangement may support somatostatin's postulated role as a neurotransmitter or neuromodulator. The strong similarity between the localization of hypothalamic SRIF in the human and rhesus monkey supports the use of the rhesus monkey as a model for the study of somatostatin as a neuroendocrine regulatory in the human.     

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 evidence for anti-LHRH and anti-ACTH activity in the "F" antiserum.

An antiserum which has previously been thought to be specific for LHRH-like immunoreactive material was shown to contain two populations of antibodies, one demonstrating anti-LHRH activity and the other anti-ACTH(1-24) activity. In rat and mouse, ACTH(1-24)-like immunoreactive substance is present in perikarya within the basal hypothalamus and in fibers in arcuate, periventricular and dorsomedial nuclei. LHRH-like immunoreactivity is present in fibers within the median eminence and arcuate nucleus, in a few fibers running along the ventral border of the hypothalamus, and in a small number of cell bodies within the medial basal hypothalamus.     

Localization of ACTH in the human hypothalamus

Summary Using an antiserum to porcine ACTH and the unlabeled antibody peroxidase-antiperoxidase technique, we have found that ACTH is present in neuronal cell bodies located exclusively in the arcuate nucleus of the human hypothalamus. ACTH-containing fibers are distributed extensively throughout the hypothalamus with the greatest density in the periventricular nucleus. No concentration of ACTH fibers could be observed in the neurovascular zone of the pituitary stalk.     

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.     

Immunocytochemical localization of neuropeptides in the hypothalamus of the Japanese long-fingered bat,Miniopterus schreibersii fuliginosus

Summary To elucidate the role of hypothalamic neuropeptides in regulation of reproductive phenomena of seasonally breeding feral mammals, we used Japanese long-fingered bats, Miniopterus schreibersii fuliginosus, for immunocytochemical study of distribution of the following neuropeptides in the hypothalamus: arginin vasopressin, oxytocin, luteinizing hormone-releasing hormone, somatostatin, corticotropin-releasing factor, and growth hormone-releasing factor. The size, shape and location of supraoptic, paraventricular, suprachiasmatic, and arcuate nuclei of the bat were determined. Arginin vasopressin-and oxytocin-immunoreactive magnocellular neurons were found in the supraoptic and paraventricular nuclei, where they exhibited separate distribution into two distinct groups. Parvocellular arginin vasopressin neurons occurred only in the suprachiasmatic nucleus. The hibernating bats exhibited slightly increased numbers of vasopressin and oxytocin neurons in the supraoptic and paraventricular nuclei. The pregnant bat displayed further increased numbers of vasopressin and oxytocin neurons in both nuclei. Somatostatin-immunoreactive neurons in the paraventricular nucleus were also immunopositive to anti-oxytocin serum, while those in the ventromedial and arcuate nuclei reacted solely to anti-somatostatin serum. They projected to the anterior median eminence and infundibular stalk. Luteinizing hormone-releasing hormone-immunoreactive perikarya were scattered throughout the basal hypothalamus, being particularly abundant in the arcuate nucleus. They were larger in size in hibernating bats than those in normal (non-pregnant) and pregnant females. They projected fibers mainly to the internal layer of the median eminence and infundibular stalk. A few luteinizing hormone-releasing hormone-reactive fibers were also observed in the organum vasculosum laminae terminalis, lateral habenular nuclei, pineal stalk, retroflexus fasciculus, and olfactory tubercle. Corticotropin releasing factor-immunoreactive perikarya were distributed in the paraventricular nucleus and medial preoptic area and projected into the external layer of the anterior median eminence, while growth hormone-releasing factor-immunoreactive perikarya occurred only in the arcuate nucleus and projected into the posterior part of the median eminence.     

The bifunctional role of pro-opiomelanocortin derivatives in the mediobasal hypothalamus of the rat

In the present study, a polyclonal antibody against pro-opiomelanocortin derivatives was characterized biochemically. Its immunoreactivity with structures of the arcuate nucleus and the median eminence was investigated by means of the immunogold method and compared with its reaction on adenohypophyseal cells with and without pre-adsorption with pro-opiomelanocortin derivatives. The antiserum detects ACTH and its fragments, in particular alpha-MSH, and beta-endorphin. In the adenohypophysis gold particles are exclusively located on small secretory granules situated in the periphery of branched cells. In the perikarya of the arcuate nucleus gold particles are observed on terminal vesicles abutting from the cis-face of the Golgi apparatus, on granules in its direct vicinity and on small dense core vesicles preferentially located in the cell periphery. Immunoreactive gold-labeled fiber profiles are found in a sub- or intra-ependymal position as well as in the nuclear neuropil proper. Here axodendritic and axosomatic synapses are observed. In both situations the gold particles are mostly restricted to the small dense core vesicles and do not decorate the synaptic vesicles. In the median eminence gold labeled fibers are detected in all layers. The labeled fibers can be closely apposed to tanycytic processes, without, however, forming special contact differentiations. In direction to the perivascular layer of the external zone the labeled profiles are more frequently arranged in groups intermingled with unlabeled fibers. The axons decorated with gold particles can be freely exposed to the perivascular space or are found as single processes in close vicinity to the capillary wall. Subsequent to preincubation of the native antiserum with ACTH1-39 and ACTH18-39 (= CLIP) neither adenohypophyseal cells nor perikarya and fibers in the arcuate nucleus nor axons in the median eminence are decorated with gold particles. Preincubation of the native antiserum with alpha-MSH or beta-endorphin does not change the immunoreaction with the small, peripherally situated granules in the branched adenohypophyseal cells. In neurons of the arcuate nucleus and in fibers of the median eminence, however, the immunoreaction is completely extinguished when the antibody is pre-incubated with alpha-MSH, whereas subsequent to preincubation with beta-endorphin only the amounts of labeled structures are reduced.(ABSTRACT TRUNCATED AT 400 WORDS)     

Localization of luteinizing hormone-releasing hormone in the forebrain of the pig

The distribution of luteinizing hormone-releasing hormone (LHRH)-immunostained perikarya and processes was examined in the forebrains of six sexually mature female pigs by use of indirect biotin-avidin horseradish peroxidase immunocytochemistry. Two primary antisera (Drs. Y.F. Chen and V.D. Ramirez CRR11B73 and Miles-Yeda UZ-4) yielded positive staining. Adjacent sections treated either primary antiserum preabsorbed with LHRH or with normal rabbit serum substituted for primary antiserum lacked positive staining. The greatest proportion of LHRH-immunostained perikarya were found in the medial preoptic area adjacent to the organum vasculosum of the lamina terminalis. The LHRH-immunostained perikarya were also scattered rostrally in the diagonal band of Broca, and within the lateral hypothalamic area, paraventricular nucleus, periventricular zone, suprachiasmatic nucleus, and medial basal hypothalamus. LHRH-immunostained processes, which extended from the medial preoptic area, coursed either along the ventral surface to the median eminence or medially and ventrally along the third ventricular wall ventrally to the median eminence and caudally to the level of the mammillary bodies. Extrahypothalamic processes were located adjacent to the lateral ventricular floor and the third ventricle from the lateral septal area (stria terminalis) to the level of the habenular nucleus. LHRH-immunostained neurons were unipolar, bipolar, and multipolar. Close associations between individual LHRH-immunostained neurons were observed.     

Demonstration of the tuberoinfundibular tract of the cat

Summary The distribution of dopaminergic nerve cells in the cat hypothalamus, particularly in the arcuate and periventricular nuclei, and the projections of their axons were studied by fluorescence and electron microscopy after electrothermic coagulation. The majority of these perikarya were located in the arcuate nucleus and the periventricular nucleus dorsocaudal to the optic chiasma. Large lesions caused a wide and diffuse depletion of dopamine fluorescence within the external layer; small lesions caused ipsilateral partial depletion of the dopamine fluorescence. Electron microscopic observations in animals with a lesioned arcuate nucleus revealed that in the external layer degenerating nerve terminals are engulfed by glial processes. In some cases nerve fibers had entirely disappeared and a heavy reactive proliferation of glial processes was observed. Persistence of the form of the median eminence in spite of the extensive degeneration of its nervous elements is considered to depend upon this glial proliferation.Dedicated to Professor W. Bargmann in honour of his 70th birthday     

Hypothalamic and extrahypothalamic distribution of somatostatin-immunoreactive elements in the rat brain

Summary Using a highly sensitive antibody to somatostatin, its hypothalamic and extrahypothalamic distribution in the rat was re-examined by light microscopic immunohistochemistry (PAP-method). The scattered somatostatin-producing perikarya occur in multiple layers within the subependymal neuropil surrounding the third ventricle. They supply with short-distance projections the following hypothalamic nuclei: 1) preoptic nuclei (especially their suprachiasmatic and medial components), 2) the peripheral zones of the suprachiasmatic nuclei, 3) the ventromedial and 4) arcuate nuclei, and 5) the ventral premammillary nuclei. Furthermore, the following long-distance projections have been observed: In a rostral direction (A1) rostral of the anterior commissure to the lamina terminalis, (A2) to the OVLT, (A3) to the olfactory tubercle, and (A4) rostrally and caudally by-passing the anterior commissure to the dorsal part of the stria terminalis.More caudally, at the retrochiasmatic level an ascending dorso-lateral projection joins the ventral amygdalo-hypothalamic pathway in a reciprocal manner (B1). In addition, a descending ventrolateral tract projects to the optic tract bending dorsal to it in different directions: (C1) medial to the median eminence, (C2) lateral to the corticomedial amygdala, and (C3) caudal for additional support of the arcuate and ventral premammillary nuclei.The principal tract of somatostatin-containing fibers descends in the subependymal neuropil to the median eminence (D).The results are discussed with reference to a possible participation of the somatostatin fiber system in the afferent branch of the circuit connecting the hypothalamus with the amygdala via the stria terminalis.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr. 569/2) and Stiftung Volkswagenwerk.     

Localization of hormone secreting pathways in the brain by immunohistochemistry and light microscopy: a review.

Immunocytochemical techniques are now being used to localize hypothalamic neurosecretory hormones and related peptides in the mammalian brain. The data are probably incomplete, due primarily to false negative results. A number of previous assumptions concerning these pathways have been confirmed while other unexpected results were obtained. As expected, vasopressin and oxytocin and their associated proteins, neurophysins, were found in the magnocellular cell bodies of the hypothalamus and in their axonal projections to the neural lobe of the pituitary. Gonadotropin-releasing hormone (Gn-RH), somatostatin, and thyrotropin-releasing hormone (TRH) were located in what appears to be parvicellular nerve terminals on portal capillaries. Gn-RH has been found in perikarya in the arcuate nucleus, which is considered a source of fibers to the portal capillary bed. An extensive network of cell bodies and fibers in the preoptic area was also found to contain Gn-RH, and others in the periventricular nucleus in the anterior hypothalamus reacted with antiserum to somatostatin. Unexpected was considerable evidence that vasopressin is secreted directly into hypophyseal portal blood. This hormone and its neurophysin were also found in parvicellular neurons in the suprachiasmatic nucleus of rodents. All the hormones were found in fibers in the organum vasculosum of the lamina terminalis and in the posterior pituitary gland.     

Immunocytochemical localization of growth hormone releasing factor (GHRF)-containing structures in the rat brain using anti-rat GHRF serum

The distribution of growth hormone releasing factor (GHRF) immunoreactive structures in the rat hypothalmus was studied after colchicine treatment with PAP immunocytochemistry in vibratome sections using an antiserum directed to rat hypothalamic GHRF. The majority of the GHRF-immunoreactive cell bodies were found in the arcuate nucleus, the medial perifornical region, and the ventral premammillary nuclei of the hypothalamus. Scattered cells were seen in the lateral basal hypothalamus, the medial and lateral portions of the ventromedial nucleus, and the dorsomedial and paraventricular nuclei. Immunoreactive fibers were observed in all the regions mentioned above. GHRF terminals were located in the central region of the median eminence. In addition, GHRF-immunoreactive neuronal processes were seen in the ventral region of the dorsomedial nucleus, the medial preoptic and suprachiasmatic regions, dorsal portion of the suprachiasmatic nucleus, bed nucleus of the stria terminals and the hypothalamic portion of the stria terminals. The localization of GHRF-immunoreactive terminals in the median eminence reinforces the view that GHRF plays a physiological role in the regulation of pituitary function. In addition, the localization of GHRF-immunoreactive structures in areas not usually considered to project to the median eminence suggest that GHRF may act as a neuromodulator or neurotransmitter.     

Immunohistochemical mapping of galanin-like neurons in the rat central nervous system

Using an antiserum generated in rabbits against synthetic galanin (GA) and the indirect immunofluorescence method, the distribution of GA-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system (CNS) and a detailed stereotaxic atlas of GA-like neurons was prepared. GA-like immunoreactivity was widely distributed in the rat CNS. Appreciable numbers of GA-positive cell bodies were observed in the rostral cingulate and medial prefrontal cortex, the nucleus interstitialis striae terminalis, the caudate, medial preoptic, preoptic periventricular, and preoptic suprachiasmatic nuclei, the medial forebrain bundle, the supraoptic, the hypothalamic periventricular, the paraventricular, the arcuate, dorsomedial, perifornical, thalamic periventricular, anterior dorsal and lateral thalamic nuclei, medial and central amygdaloid nuclei, dorsal and ventral premamillary nuclei, at the base of the hypothalamus, in the central gray matter, the hippocampus, the dorsal and caudoventral raphe nuclei, the interpeduncular nucleus, the locus coeruleus, ventral parabrachial, solitarii and commissuralis nuclei, in the A1, C1 and A4 catechaolamine areas, the posterior area postrema and the trigeminal and dorsal root ganglia. Fibers were generally seen where cell bodies were observed. Very dense fiber bundles were noted in the septohypothalamic tract, the preoptic area, in the hypothalamus, the habenula and the thalamic periventricular nucleus, in the ventral hippocampus, parts of the reticular formation, in the locus coeruleus, the dorsal parabrachial area, the nucleus and tract of the spinal trigeminal area and the substantia gelatinosa, the superficial layers of the spinal cord and the posterior lobe of the pituitary. The localization of the GA-like immunoreactivity in the locus coeruleus suggests a partial coexistence with catecholaminergic neurons as well as a possible involvement of the GA-like peptide in a neuroregulatory role.     

Prolactin-secreting neurons in the dorsolateral hypothalamus in Sprague-Dawley rats

By means of immunocytochemical techniques ovine prolactin like immunoreactivity (oPRL-LIR) has been demonstrated in the perikarya located around fornix in the dorso-lateral part of the rat hypothalamus. No PRL-LIR was observed in the arcuate n. perikarya. Immunoreactive fibers were present in the hypothalamus, medial thalamus, accumbens and amygdaloid nuclei.     

Immunoreactive beta-endorphin and ACTH in the same neurons of the hypothalamic arcuate nucleus in the rat.

Immunoreactive ACTH and beta-endorphin (beta-End) were localized in the brain and pituitaries of normal and colchicine-treated rats, using the immunoperoxidase method at the light microscopic level. On adjacent serial 5-micron paraffin sections of anterior pituitaries, both ACTH and beta-End could be found in the same cells. On adjacent 5-micron paraffin sections of brains of colchicine-treated rats, both ACTH and beta-End could be found in the same perikarya of hypothalamic arcuate nucleus neurons. It appeared that all perikarya containing beta-End contained ACTH as well, suggesting that neurons producing beta-End also produce ACTH. Pathways of ACTH fibers corresponded to pathways of beta-End fibers. These findings suggest that the synthesis, and transport, of ACTH and beta-End are linked in the brain as well as in the pituitary, possibly through a common precursor.     

Neurons containing alpha-melanocyte stimulating hormone and beta-endorphin immunoreactivity in the cat hypothalamus

Immunohistochemical studies were conducted on sections of cat hypothalamus in order to determine the distribution of neurons containing alpha-melanocyte stimulating hormone and beta-endorphin immunoreactivity. A large number of neurons in the arcuate nucleus were stained after incubation of sections with antisera to either substance. Analysis of serial sections suggested that each neuron revealed with one antiserum was also revealed with the other antiserum, indicating the co-existence of alpha-melanocyte stimulating hormone and beta-endorphin immunoreactivity within these arcuate neurons. In contrast, a more diffuse group of lateral hypothalamic neurons which extended from the retrochiasmatic level to the posterior hypothalamus were stained only with the antiserum directed against alpha-melanocyte stimulating hormone. The present results largely confirm findings in the rat hypothalamus, although the lateral hypothalamic group of alpha-melanocyte stimulating hormone immunoreactive neurons appears to be more extensive in the cat.