Distribution of neuropeptide Y-like immunoreactivity in the hypothalamus of the adult golden hamster

The distribution of neuropeptide Y (NPY)-like immunoreactivity within the hypothalamus of the adult golden hamster was investigated with conventional immunohistochemical techniques. Neuropeptide Y immunoreactive cell bodies were found in greatest numbers in the arcuate nucleus while a few stained perikarya were seen in the internal and subependymal zones of the median eminence. Isolated perikarya were observed in the anterior commissure and supracommissural portion of the interstitial nucleus of the stria terminalis. Immunoreactive axons were located throughout the hypothalamus with the highest concentrations in the subependymal and internal zones of the median eminence, the interstitial nucleus of the stria terminalis, the medial preoptic area, and in the following nuclei: periventricular, suprachiasmatic, paraventricular, perifornical, median preoptic, and arcuate. Moderate to dense plexuses of immunoreactive fibers were observed in the anterior, lateral, and posterior hypothalamic areas and in the infundibular stalk. The supraoptic nucleus and lateral preoptic area displayed a small number of labeled axons whereas the ventromedial nucleus contained only a few fibers. NPY immunoreactive fibers were present in the optic tract and in the dorsomedial aspect of the optic chiasm. Labeled fibers penetrated the ependymal lining of the third ventricle throughout the ventral aspect of the periventricular zone. Additional fibers were observed in the pia lining the ventral aspect of the hypothalamus. This systematic analysis of hypothalamic NPY immunoreactivity in the adult golden hamster suggests that a portion of the labeled fibers display a distribution that is similar to previously described noradrenergic fibers in the hypothalamus.     

Immunohistochemical localization of avian pancreatic polypeptide-like immunoreactivity in the rat hypothalamus

The distribution of avian pancreatic polypeptide-like (APP) immunoreactivity within the rat hypothalamus was investigated with the indirect immunoperoxidase method. APP immunoreactive perikarya are found in largest numbers in the retrochiasmatic area, the arcuate nucleus, and the supracommissural portion of the interstitial nucleus of the stria terminalis. Small clusters of immunoreactive neurons are also consistently observed in the ventral aspect of the medial preoptic area and lateral hypothalamic area, immediately dorsolateral to the optic chiasm and tracts. These neurons are apparent in all animals but are more intensely strained and occur in larger numbers following colchicine pretreatment. Other immunoreactive neurons are visible only in colchine-treated rats and are scattered throughout the anterior and lateral hypothalamic areas and the supramammillary nucleus. Immunoreactive axons and terminal fields present an extensive and highly characteristic distribution throughout the hypothalamus, which in many instances exhibits differential distribution within specific subfields of hypothalamic nuclei and areas. The heaviest concentrations of APP immunoreactive axons are present in the periventricular nucleus throughout the rostrocaudal extent of the hypothalamus, the ventrolateral portion of the suprachiasmatic nucleus, the retrochiasmatic area, the parvocellular paraventricular nucleus, the ventral supraoptic nucleus, the perifornical nucleus, the ventral dorsomedial nucleus, and the arcuate nucleus. Moderate plexuses of immunoreactive fibers are also present in the medial preoptic area, the anterior and lateral hypothalamic areas, the nucleus circularis, the median eminence, and the ventral premammillary area. Other areas, such as the ventromedial nucleus, contain virtually no immunoreactive axons but are encapsulated by a dense plexus of immunoreactive terminals. The distribution of a major component of APP immunoreactive fibers exhibits a marked similarity to that of previously described norepinephrine-containing hypothalamic afferents. Other groups of APP immunoreactive perikarya and fibers appear to represent components of intrinsic diencephalic systems.     

Mapping of neuropeptide Y-like immunoreactivity in the feline hypothalamus and hypophysis

The distribution of neuropeptide Y (NPY) in the cat hypothalamus and hypophysis was studied with the indirect immunofluorescence technique of Coons and co-workers (Coons, Leduc, and Connolly: J. Exp. Med. 102:49-60, 1955), which provided a detailed map of NPY-like immunoreactive neurons. The immunolabelling was detected in cell bodies, fibers, and terminallike structures widely distributed throughout the whole hypothalamus. A large population of medium-sized NPY-like immunoreactive cell bodies was localized in the area of arcuate nucleus. The number of immunoreactive cell bodies visualized was dramatically increased after intracerebroventricular injections of colchicine. Numerous immunolabelled cell bodies were also visible in the median eminence and scattered in the lateral hypothalamic area. Dense plexuses of NPY-immunoreactive fibers were observed in the arcuate nucleus, internal layer of median eminence, periventricular zone, and paraventricular nucleus. Other regions of hypothalamus displaying numerous NPY-like immunoreactive fibers included dorsal and ventrolateral hypothalamic areas. In contrast, certain hypothalamic areas were almost devoid of NPY-like immunoreactive fibers-namely, the mammillary bodies and suprachiasmatic nucleus. Finally, in neurohypophysis, bright immunofluorescent fibers were observed along the pituitary stalk and penetrating the neural lobe. These results suggest the widespread distribution of the NPY-containing neuronal systems in the cat hypothalamus and hypophysis.     

Ventral lateral geniculate nucleus efferents to the rat suprachiasmatic nucleus exhibit avian pancreatic polypeptide-like immunoreactivity

The distribution of avian pancreatic polypeptide-like (APP) immunoreactivity was investigated in the suprachiasmatic nucleus (SCN) of the rat hypothalamus with immunohistochemical methods. Specificity of the antisera was established by the absence of all immunoreactive staining in tissue incubated in antisera which had been preabsorbed with the pure APP antigen. In addition, the antisera exhibited no significant cross reactivity with vasoactive intestinal polypeptide, vasopressin, somatostatin, or secretin. Within the rat SCN, APP immunoreactivity is restricted to varicose axons in the ventral and lateral aspects of the nucleus; the dorsomedial component of the nucleus is totally devoid of immunoreactivity and immunoreactive perikarya are not present in any portion of the SCN. The immunoreactive axons in the ventrolateral portion of the nucleus form an extensive plexus which is distributed in a pattern closely corresponding to the distribution of retinal and ventral lateral geniculate (vLGN) efferents to the SCN. No immunoreactive perikarya are observed in the retina following immunoperoxidase staining for APP and neither unilateral nor bilateral enucleation causes an observable alteration in the pattern of APP axon distribution within the SCN, thus indicating that the fiber plexus is not of retinal origin. In contrast, APP immunoreactive neurons are present in the same area of the vLGN in which retrogradely filled neurons have been demonstrated following iontophoretic injection of HRP into the SCN. Bilateral electrolytic lesions of the vLGN result in a total loss of immunoreactive axons in both SCN. Unilateral vLGN lesions cause a loss of approximately 60 to 75% of the immunoreactive fibers in the ipsilateral SCN with a lesser contralateral loss. These observations provide further information on the organization of afferents to the rat SCN and demonstrate that the vLGN projection is chemically distinct from other SCN afferents.     

Distribution of galanin-like immunoreactivity in the brain of Rana esculenta and Xenopus laevis.

The immunocytochemical distribution of galanin-containing perikarya and nerve terminals in the brain of Rana esculenta and Xenopus laevis was determined with antisera directed toward either porcine or rat galanin. The pattern of galanin-like immunoreactivity appeared to be identical with antisera directed toward either target antigen. The distribution of galanin-like immunoreactivity was similar in Rana esculenta and Xenopus laevis except for the absence of a distinct laminar distribution of immunoreactivity in the optic tectum of Xenopus laevis. Galanin-containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in the pars medialis of the amygdala and the preoptic area. In the diencephalon, immunoreactive perikarya were detected in the caudal half of the suprachiasmatic nucleus, the nucleus of the periventricular organ, the ventral hypothalamus, and the median eminence. In the mesencephalon, immunoreactive perikarya were detected near the midline of the rostroventral tegmentum, in the torus semicircularis and, occasionally, in lamina A and layer 6 of the optic tectum. In the myelencephalon, labelled perikarya were detected only in the caudal half of the nucleus of the solitary tract. Immunoreactive nerve fibers of varying density were observed in all subdivisions of the brain with the densest accumulations of fibers occurring in the pars lateralis of the amygdala and the preoptic area. Dense accumulations of nerve fibers were also found in the lateral septum, the medial forebrain bundle, the periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the mesencephalic central gray, the laminar nucleus of the torus semicircularis, several laminae of the optic tectum, the interpeduncular nucleus, the isthmic nucleus, the central gray of the rhombencephalon, and the dorsolateral caudal medulla. The extensive system of galanin-containing perikarya and nerve fibers in the brain of representatives of two families of anurans showed many similarities to the distribution of galanin-containing perikarya and nerve fibers previously described for the mammalian brain.     

Immunocytochemical distribution of [Met]enkephalin-Arg-Gly-Leu immunoreactivity in the rat diencephalon

Recently, [Met]Enkephalin-Arg-Gly-Leu (MEAGL) was isolated from bovine adrenal glands, and it was found to be derived exclusively from proenkephalin. Therefore, we investigated the distribution of MEAGL-like immunoreactive neuronal perikarya and fibers in the rat diencephalon pretreated with colchicine by PAP immunocytochemistry. In the thalamus MEAGL immunoreactive neuronal perikarya were distributed in the paraventricular nucleus and the ventral part of the lateral geniculate nucleus. Immunoreactive fibers were found in the paraventricular, paracentral, anteroventral, reuniens and rhomboid nuclei. In addition, immunoreactive fibers were also noted in the anterior pretectal nucleus. In the hypothalamus, immunoreactive neuronal perikarya were observed in the medial preoptic area, anterior and lateral hypothalamic nuclei, perifornical region, parvocellular and postero-magnocellular regions of paraventricular nucleus, ventromedial nucleus, dorsomedial nucleus, arcuate nucleus, premammillary, medial mammillary and lateral mammillary nuclei. The distribution of immunoreactive fibers was similar to that of neuronal perikarya. However, immunoreactive fibers were also observed in the supraoptic and suprachiasmatic nuclei where no immunoreactive neuronal perikarya were detected. Numerous immunoreactive fibers were detected in the external layer of the median eminence, but there were few in the internal layer. The similarity and difference in the distribution between MEAGL and other proenkephalin peptides such as [Met]enkephalin were also discussed.     

Neurotensin in the rat median eminence: the possible sources of neurotensin-like fibers and varicosities in the external layer

The possible sources of neurotensin-like immunoreactive axons in the median eminence were studied after several experimental surgical approaches including unilateral lateral retrochiasmatic area transection, midsagittal knife cut through the median eminence, complete surgical isolation of the medial basal hypothalamus and bilateral paraventricular nucleus lesions. Both immunohistochemical and radioimmunoassay data demonstrate that neurotensin-containing neuronal located in the hypothalamic arcuate nuclei represent the main source of neurotensin occurring in the external zone of the median eminence of the rat: (1) neither the complete isolation of the medial basal hypothalamus nor the transection of the major neuronal input channel to the median eminence in the lateral retrochiasmatic area altered neurotensin-like immunoreactivity in the median eminence; (2) bilateral lesioning of the paraventricular nucleus resulted in insignificant changes of neurotensin level in the median eminence; and (3) two days after lesioning the median eminence an increased amount of retrogradely accumulated neurotensin-like immunoreactivity was found in several perikarya of the arcuate nuclei due to the blockage of axonal transport in the transected fibers. Retrograde accumulation of neurotensin-like material in other cells scattered in the anterior hypothalamus (in the paraventricular, paraventricular and anterior hypothalamic nuclei) indicates that in addition to the arcuate neurons these neurons may also participate in the neurotensin innervation of the median eminence.     

The distribution of 5-HT immunoreactive systems in the brain of a saurian, the chameleon

The distribution of serotonin immunoreactive cell bodies and fibers was studied in the chameleon brain by using the immunohistochemical technique with antisera against serotonin coupled to a carrier with glutaraldehyde. Serotonin perikarya were found in the caudal midbrain tegmentum, in the lateral part of the nucleus reticularis isthmi, the lateral part of the nucleus interpeduncularis and along the midline in the raphe superior. More caudally, the serotonin immunoreactive cell bodies were located along the nucleus raphe inferior and ventrolaterally in the vicinity of the olivary complex. No immunoreactive cell bodies were found in the spinal cord nor in the paraventricular organ (PVO) of the hypothalamus. Immunoreactive fibers were observed in the entire brain. Prominent concentrations were found in the dorsal cortex, lateral septum, lateral geniculate nucleus, median eminence, pretectal nucleus, nucleus interpeduncularis, vestibular nucleus and olivary complex. Descending serotonin immunoreactive fibers were found in particular in the ventral motoneuron area in the spinal cord. One of the most interesting findings in this study was the lack of immunoreactive CSF contacting neurons in the PVO and the observation of an extensive plexus of supraependymal fibers, a feature reported so far only in mammals.     

Distribution of proenkephalin-derived peptides in the brain of Rana esculenta

The immunocytochemical distribution of authentic proenkephalin-containing perikarya and nerve fibers in the brain of Rana esculenta was determined with antisera directed toward different epitopes of preproenkephalin. The pattern of proenkephalinlike immunoreactivity was similar with antisera directed toward [Met5]-enkephalin, [Met5]-enkephalin-Arg6, [Met5]-enkephalin-Arg6-Phe7, [Leu5]-enkephalin, and metorphamide; however, the intensity of the labelling varied depending on the target antigen. Proenkephalin-containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in the dorsal, medial, and lateral pallium; the medial septal nucleus; the dorsal and ventral striatum; and the amygdala. In the diencephalon, immunoreactive perikarya were detected in the preoptic nucleus, in the dorsal and ventral caudal hypothalamus, and in an area that appeared to be homologous to the paraventricular nucleus. In the mesencephalon, numerous immunoreactive perikarya were detected in layer 6 of the optic tectum and a few scattered perikarya were detected in layer 4 of the optic tectum. Immunoreactive perikarya also occurred in the laminar nucleus of the torus semicircularis. In the rhombencephalon, immunoreactive perikarya were detected in the obex region and the nucleus of the solitary tract. Immunoreactive fibers of varying density were observed in all major subdivisions of the brain with the densest accumulations of fibers occurring in the dorsal pallium, the lateral and medial forebrain bundles, the amygdala, the periventricular hypothalamus, the superficial region of the caudolateral brainstem, and in a tract that appeared to be homologous to the tractus solitarius. The extensive system of proenkephalin-containing perikarya and nerve fibers in the brain of an amphibian showed many similarities to the distribution of proenkephalin-containing perikarya and nerve fibers previously described for the amniote brain.     

Distribution of neuromedin U-like immunoreactivity in the central nervous system of Rana esculenta

The distribution of perikarya and nerve fibers containing neuromedin U-like immunoreactivity in the brain of Rana esculenta was determined with an antiserum directed toward the carboxyl terminus of the peptide. In the telencephalon, immunoreactive perikarya were found in the olfactory bulb, the medial septum, and the diagonal band. In the diencephalon, labeled perikarya were detected in the anterior and posterior preoptic areas, the dorsal nucleus of the hypothalamus, the caudal part of the infundibulum, and the posterior tuberculum. In the mesencephalon, immunoreactive cell bodies were found only in the laminar nucleus of the torus semicircularis and the anterodorsal tegmental nucleus. In the rhombencephalon, labeled perikarya were detected in the secondary visceral nucleus, the cerebellar nucleus, the central gray, and the nucleus of the solitary tract. Immunoreactive nerve fibers were observed in all areas of the brain that contained labeled perikarya. The densest accumulations were found in the nucleus accumbens; the dorsal part of the lateral septum; the periventricular region of the ventral thalamus; the lateral part of the infundibulum; the anterodorsal, anteroventral, posterodorsal, and posteroventral tegmental nuclei; and the periaqueductal region of the tegmentum. The distribution of neuromedin U-like immunoreactivity in the frog brain was substantially different from the distribution described for the rodent brain. © 1996 Wiley-Liss, Inc.     

Substance P-like immunoreactivity in the lateral cervical nucleus of the owl monkey (Aotus trivirgatus): a comparison with the cat and rat

The location of substance P (SP) in the lateral cervical nucleus (LCN) of monkeys (Aotus trivirgatus), cats, and rats was investigated with immunohistochemical methods. Light microscopic analysis showed that SP-positive fibers and terminals are evenly distributed throughout the LCN of the monkey and rat, whereas the SP labeling in the LCN of the cat is concentrated in the medial part of the nucleus, with only very sparse labeling in the lateral part. Electron microscopic examination of the monkey LCN revealed the presence of SP-like immunoreactivity within terminal boutons and unmyelinated axons. The SP-positive boutons are in synaptic contact with dendrites and, occasionally, cell bodies; they contain densely packed, clear, round synaptic vesicles, as well as dense-core vesicles. The distribution of SP-like immunoreactivity in the LCN of monkeys, cats, and rats is similar to that of nociceptive-responsive neurons demonstrated in electrophysiological experiments. The possible role of the SP-containing fibers in the transmission of nociceptive information through the LCN is discussed.     

Distribution of GABAAreceptor alpha 1 subunit-like immunoreactivity in comparision with that of enkephalin and substance P in the rat forebrain

The γ-aminobutyric acid-A receptor consists of several subunits. In this immunohistochemical study we investigated the regional distribution of the α1 subunit with an antibody directed against a specific amino acid sequence (1-9) of the α1 subunit. We compared the distribution pattern of the α1 subunit-like immunoreactivity with that of substance P- and enkephalin-like immunoreactivities in adjacent sections of the rat forebrain. α1 subunit-like immunoreactivity appeared in the form of varicosities and fibers. A band-like terminal staining pattern (woolly fibers) that has been shown by others for substance P- and enkephalin-like immunoreactivity is also observed for α1 subunit-like immunoreactivity. In contrast to substance P and enkephalin, numerous α1 subunit-like immunoreactive perikarya were found. The highest density of α1 subunit-like immunoreactive fibers and perikarya was found in the pallidal areas and the substantia nigra pars reticulata whereas the nucleus accumbens and the caudate putamen displayed a low density. α1 subunit-like immunoreactive neurons resembled typical pallidal neurons. Some of these neurons were pericellularly stained with enkephalin-like immunoreactive varicosities in the dorsal pallidum. The distribution pattern of α1 subunit-like immunoreactivity reflects a partial overlap with the substance P and enkephalin system although a differential distribution to each of these peptides was observed for cell bodies, fibers, and axon terminals. © 1995 Wiley-Liss, Inc.     

Distribution of neurotensin-containing neurons in the central nervous system of the pigeon and the chicken

Neurotensin is widely located in neurons of the central and peripheral nervous systems among mammalian species. To obtain a comparative evaluation, we examined the distribution of neurotensin-containing cell bodies and fibers in the central nervous system of the pigeon and the chicken. The pattern of localization of neurotensin immunoreactivity was similar in the two species. Abundant accumulations of neurotensin-containing cell bodies were found in the dorsolateral corticoid area, the piriform cortex, the parahippocampal area, the medial part of the frontal neostriatum, the lateral part of the caudal neostriatum, nucleus accumbens, the bed nucleus of the stria terminalis, ventral paleostriatum, the preoptic area, the ventromedial hypothalamic nucleus, the inferior hypothalamic nucleus, the infundibular hypothalamic nucleus, and the mammillary nuclei. Extremely dense networks of neurotensin-containing fibers were found in the pallial commissure, the lateral septal nucleus, the preoptic area, the periventricular gray around the third ventricle, the dorsalis hypothalamic area, the hypothalamic nuclei, the parabrachial nucleus, the locus ceruleus, and the dorsal vagal complex. Major differences of immunoreactivity between the two species were as follows. 1) The chicken neurohypophysis contained an extremely large accumulation of immunoreactive fibers, but there were few in the median eminence. The reverse was found in the pigeon. 2) The optic tectum in the pigeon contained immuroreactive cells and fibers in layers 2 and 4, but no immunoreactivity was seen in the chicken optic tectum. 3) The cerebellar cortex in the pigeon contained a small number of immunoreactive fibers, whereas that in the chicken did not. 4) The pigeon spinal cord contained immunoreactive neurons in the subependymal layer, but the chicken spinal cord did not. Our observations suggest the presence of a very wide network of neurotensin-containing neurons in the avian brain and spinal cord, which is also the case in mammals. © 1996 Wiley Liss, Inc.     

Cholinergic innervation of the monkey amygdala: an immunohistochemical analysis with antisera to choline acetyltransferase

The organization of the cholinergic innervation of the macaque monkey amygdaloid complex was investigated by means of immunohistochemical techniques and either a polyclonal antiserum or a monoclonal antibody directed against the specific synthetic enzyme choline acetyltransferase (ChAT). Adjacent series of sections were processed histochemically for the demonstration of the degradative enzyme acetylcholinesterase (AChE) or for cell bodies with thionin. The density of ChAT immunoreactivity differed substantially among the various nuclei and cortical regions of the amygdala. In general, the distribution of ChAT immunoreactivity paralleled the pattern of AChE staining. One notable exception was the presence of AChE containing cell bodies in addition to AChE positive fibers within nearly all of the nuclear and cortical regions. In contrast, ChAT immunoreactivity was associated only with fibers and terminals. The highest density of ChAT immunoreactive fibers and terminals was consistently observed in the magnocellular subdivision of the basal nucleus. Staining was substantially less dense in the more ventrally situated parvicellular subdivision. Medially, in the adjacent accessory basal nucleus, immunoreactive fibers and terminals were densest in the magnocellular and superficial subdivisions and least prominent in the parvicellular subdivision. Of the deep nuclei, the lateral nucleus generally obtained the least ChAT immunoreactive terminals and processes. Only its more densely cellular ventrolateral portion contained appreciable fiber and terminal staining. One of the more distinctive patterns of ChAT immunoreactivity was seen in the nucleus of the lateral olfactory tract. Here, ChAT positive fibers formed pericellular basket plexuses around unstained cell bodies. This unique pattern of staining was used to delineate the boundaries of the nucleus and indicated that it is present for much of the rostrocaudal extent of the amygdala. Another region of conspicuous staining on the medial surface of the amygdala was the sulcal portion of the periamygdaloid cortex. This region, associated with the sulcus semiannularis and bordering the entorhinal cortex, consistently contained dense immunoreactivity. The central nucleus also presented a somewhat idiosyncratic pattern of ChAT staining. The lateral subdivision had a diffuse distribution of immunoreactivity in which focal patches of more densely stained terminals and occasional fine fibers were embedded. In contrast, the medial subdivision contained a larger number of thicker, stained fibers without diffuse background labeling.(ABSTRACT TRUNCATED AT 400 WORDS)     

Distribution of substance P-immunoreactive elements in the preoptic area and the hypothalamus of the rat.

The localization and morphology of neurons, processes, and neuronal groups in the rat preoptic area and hypothalamus containing substance P-like immunoreactivity were studied with a highly selective antiserum raised against synthetic substance P. The antiserum was thoroughly characterized by immunoblotting; only substance P was recognized by the antiserum. Absorption of the antiserum with synthetic substance P abolished immunostaining while addition of other hypothalamic neuropeptides had no effect on the immunostaining. The specificity of the observed immunohistochemical staining pattern was further confirmed with a monoclonal substance P antiserum. The distribution of substance P immunoreactive perikarya was investigated in colchicine-treated animals, whereas the distribution of immunoreactive nerve fibers and terminals was described in brains from untreated animals. In colchicine-treated rats, immunoreactive cells were reliably detected throughout the preoptic area and the hypothalamus. In the preoptic region, labeled cells were found in the anteroventral periventricular and the anteroventral preoptic nuclei and the medial and lateral preoptic areas. Within the hypothalamus, immunoreactive cells were found in the suprachiasmatic, paraventricular, supraoptic, ventromedial, dorsomedial, supramammillary, and premammillary nuclei, the retrochiasmatic, medial hypothalamic, and lateral hypothalamic areas, and the tuber cinereum. The immunoreactive cell groups were usually continuous with adjacent cell groups. Because of the highly variable effect of the colchicine treatment, it was not possible to determine the actual number of immunoreactive cells. Mean soma size varied considerably from one cell group to another. Cells in the magnocellular subnuclei of the paraventricular and supraoptic nuclei were among the largest, with a diameter of about 25 microns, while cells in the supramammillary and suprachiasmatic nuclei were among the smallest, with a diameter of about 12 microns. Immunoreactive nerve fibers were found in all areas of the preoptic area and the hypothalamus. The morphology, size, density, and number of terminals varied considerably from region to region. Thus, some areas contained single immunoreactive fibers, while others were innervated with such a density that individual nerve fibers were hardly discernible. During the last decade, knowledge about neural organization of rodent hypothalamic areas and mammalian tachykinin biochemistry has increased substantially. In the light of these new insights, the present study gives comprehensive morphological evidence that substance P may be centrally involved in a wide variety of hypothalamic functions. Among these could be sexual behavior, pituitary hormone release, and water homeostasis.     

Distribution of neuropeptide Y-like immunoreactive cell bodies and fibers in the brain stem of the cat

By using intratissue injections of colchicine and an indirect immunoperoxidase technique, we studied the distribution of cell bodies and fibers containing neuropeptide Y-like immunoreactivity in the brain stem of the cat. The densest clusters of immunoreactive perikarya were observed in the following nuclei: anteroventral cochlear, lateral reticular (internal and external divisions), dorsal tegmental, inferior colliculus and dorsal nucleus of the lateral lemniscus. By contrast, the nuclei abducens, the nucleus of the trapezoid body, preolivary, interpeduncularis, infratrigeminal, gigantocellular tegmental field, coeruleus and dorsal motor nucleus of the vagus had the lowest density. Finally, a moderate density of neuropeptide Y-like immunoreactive cell bodies was found in the nuclei: lateral tegmental field, laminar spinal trigeminal, praepositus hypoglossi, superior colliculus, lateral vestibular and motor trigeminal. In addition, a mapping of the neuropeptide Y-like immunoreactive fibers was carried out. Thus, the densest network of immunoreactive fibers was observed in the laminar spinal trigeminal nucleus. The nuclei periaqueductal gray, inferior central, praepositus hypoglossi, postpyramidal raphe, dorsal raphe, incertus and medial vestibular contained a moderate density of immunoreactive fibers, whereas the nuclei interpeduncularis, inferior colliculus, superior central, gracile, retrorubral, K?lliker-Fuse, dorsal tegmental, ambiguus and alaminar spinal trigeminal had the lowest density of neuropeptide Y-like immunoreactive fibers. The anatomical location of neuropeptide Y-like immunoreactivity suggests that the peptide could play an important role in several physiological functions, e.g., those involved in cardiovascular, auditory, motor, visual, nociceptive and somatosensory mechanisms.     

Vasoactive intestinal peptide in the hypothalamohypophysial system of the Mongolian gerbil

By use of the indirect peroxidase-antiperoxidase immunohistochemical technique the location of perikarya and fibers exhibiting vasoactive intestinal peptide (VIP)-like immunoreactivity was investigated in the hypothalamus and the posterior pituitary of the Mongolian gerbil (Meriones unguiculatus), because of the involvement of VIP in several neuroendocrine functions. In the hypothalamus, a large number of VIP-immunoreactive perikarya were seen in the ventromedial part of the suprachiasmatic nucleus. Few VIP-positive perikarya were present in the periventricular, paraventricular, and supraoptic nuclei and in the medial preoptic area close to the third ventricle. The perikarya in the paraventricular nucleus projected fibers in the direction of the median eminence. In the median eminence VIP-immunoreactive fibers were present especially in the external layer, concentrated in the perivascular spaces surrounding the portal vessels. Scattered VIP-immunoreactive fibers were also located in the internal layer of the median eminence as well as in the posterior pituitary lobe. In the latter, large VIP-positive Herring-like bodies were observed. With receptor autoradiography a large number of grains were demonstrated in the anterior pituitary lobe in contrast to the neural lobe. Many VIP-positive fibers and some perikarya were observed within the ependyma covering the rostroventral part of the third ventricle. Finally, fibers exhibiting VIP immunoreactivity were also seen in the organum vasculosum laminae terminalis (OVLT). These results support the concept that VIP is released into the portal vascular system and plays a role in the regulation of the activity of the anterior pituitary. In addition, VIP might be secreted into the cerebrospinal fluid of the third ventricle.     

Localization of FMRFamide-like immunoreactivity in the brain of the viviparous skink (Chalcides chalcides)

Neuroanatomical distribution of FMRFamide-like immunoreactivity was investigated in the brain and olfactory system of the viviparous skink, Chalcides chalcides. In the adult brain FMRFamide immunoreactive (ir) perikarya were observed in the diagonal band of Broca, medial septal nucleus, accumbens nucleus, bed nucleus of the anterior commissure, periventricular hypothalamic nucleus, lateral forebrain bundle, and lateral preoptic, subcommissural, suprachiasmatic and lateral hypothalamic areas. This pattern was seen in both male and female brains. Though all major brain areas showed FMRFamide-ir innervation, the densest ir fiber network was observed in the hypothalamus. During development, ir elements were observed for the first time in embryos at mid-pregnancy. FMRFamide perikarya were located along the ventral surface of the vomeronasal nerve, in the olfactory peduncle mediobasally, as well as in the anterior olfactory nucleus and olfactory tubercle. Furthermore, some ir neurons were observed in the rhombencephalic reticular substance; however, the ir fiber network was poorly developed. Later in development FMRFamide-ir neurons appeared also in the bed nucleus of the anterior commissure as well as the rhombencephalic nucleus of solitary tract and the dorsal motor nucleus of vagus nerve. In juveniles, the distribution profile of FMRFamide immunoreactivity was substantially similar to that of the adults, with a less widespread neuronal distribution and a more developed fiber network. Ontogenetic presence of FMRFamide immunoreactivity in the nasal area has been linked to the presence of a nervus terminalis in this reptile.     

Distribution of cholecystokinin-like-immunoreactive neurons in the guinea pig forebrain

The distribution of cholecystokinin (CCK)-immunoreactive nerve fibers and cell bodies was studied in the forebrain of control and colchicine-treated guinea pigs by using an antiserum directed against the carboxyterminus of CCK octapeptide (CCK-8) in the indirect immunoperoxidase technique. Virtually all forebrain areas examined contained immunoreactive nerve fibers. A dense innervation was visualized in; neocortical layers II-III, piriform cortex, the medial amygdala, the medial preoptic area, a circumventricular organ-like structure located at the top of the third ventricle in the preoptic area, the subfornical organ, the posterior bed nucleus of the stria terminalis, the posterior globus pallidus (containing labeled woolly fiber-like profiles), the ventromedial hypothalamus, the median eminence, and the premammillary nucleus. A moderately dense innervation was visualized elsewhere excepted in the septum and thalamus where labeled axons were comparatively few. Immunoreactive perikarya were abundant in: neocortex (especially layers II-III), piriform cortex, amygdala, the median preoptic nucleus, the bed nucleus of the stria terminalis, the hypothalamic paraventricular (parvicellular part), arcuate, and dorsomedial (pars compacta) nuclei, the dorsal and perifornical hypothalamic areas, and throughout the thalamus. Areas also containing a moderate number of labeled cell bodies were the medial preoptic area, the globus pallidus, the caudate-putamen, and the periventromedial area in the hypothalamus. Immunostained perikarya were absent or only occasionally observed in the septum, the suprachiasmatic nucleus, the magnocellular hypothalamoneurohypophyseal nuclei, and the ventral mesencephalon. In the adenohypophysis, corticomelanotrophs were labeled in both males and females, and thyrotrophs were labeled in females only. This distribution pattern of CCK-8 immunoreactivity is compared to those previously recorded in other mammals. This shows that very few features are peculiar to the the guinea pig. It is discussed whether some interspecific differences in immunostaining are real rather than methodological.     

Neurotensin-containing cell bodies, fibers and nerve terminals in the brain stem of the rat: Immunohistochemical mapping

Neurotensin immunoreactive perikarya, fibers and nerve terminals, visualized by the indirect immunohistofluorescent method in colchicine-pretreated animals, are localized in many discrete regions of the rat brain stem. Cell body groups are found in the inner aspect of the substantia gelatinosa of the caudal trigeminal nuclear complex, the nucleus of the solitary tract, the parabrachial nuclei, the locus coeruleus, the dorsal raphé nucleus, the periaqueductal gray matter, and the ventral tegmental area of Tsai. These areas of cell body density are accompanied by concentrations of fibers and terminals, while the occasional positive perikaryon noted in the dorsal cochlear nucleus is accompanied by only sparse fluorescent fiber/terminal patterns. Other brain stem regions, such as the floor of the fourth ventricle and aspects of the caudal ventrolateral reticular formation, possess substantial numbers of fibers and terminals that are not accompanied by cell bodies. Many aspects of this distribution coincide with the brain stem distribution of the enkephalin pentapeptides, though significant differences in localization are also evident. Interactions of neurotensin with other neurotransmitter candidates are also suggested by its presence in areas enriched in norepinephrine, dopamine, serotonin, and substance P. Certain neurotensin localizations suggest an association of the peptide with functional brain systems preferentially involving these regions. In particular periaqueductal gray and substantia gelatinosa neurotensin synapses are plausible sites for the analgesia elicited after intercisternal injection of low doses of neurotensin.