The efferent connections of the lateral septal nucleus in the guinea pig: intrinsic connectivity of the septum and projections to other telencephalic areas

Summary The distribution of efferent fibers originating in the lateral septal nucleus was investigated in guinea pigs by means of anterograde tracing with Phaseolus vulgaris-leucoagglutinin (PHA-L). Special emphasis was placed on the intraseptal fiber systems. The fibers originating from the different subnuclei of the lateral septal nucleus formed massive horizontal connections in the rostrocaudal axis. Projections to the contralateral, congruent subnuclei were also detected. In the medial septum/diagonal band of Broca complex the largest number of PHA-L-stained fibers was found after application of the tracer into the dorsal subnucleus of the lateral septal nucleus; the density of the efferent fibers decreased progressively after injection into the intermediate or ventral subnuclei. In all cases the diagonal band contained a much higher number of efferent fibers from the lateral septal nucleus than from the medial septal nucleus. In the medial septal nucleus, terminal labeling was generally sparse. Other telencephalic areas (organum vasculosum of the lamina terminalis, nucleus accumbens, bed nucleus of the stria terminalis, amygdala, hippocampal complex, and other cortical areas) contained varying numbers of labeled projections. In double-labeling experiments, a close spatial relationship between PHA-L-stained fibers and vasoactive intestinal polypeptide-immunoreactive perikarya was observed in several of these target areas.     

Immunocytochemical localization of somatostatin in human brain

The distribution of somatostatin (SRIF) was examined in normal human forebrain, using thick vibratome cut sections. The unlabeled antibody enzyme method of immunocytochemistry revealed a widespread distribution of SRIF immunoreactive neurons and fibers throughout the septum, diencephalon and corpus striatum. Within the septum SRIF neurons and fibers were observed in the medial and lateral septal nuclei, the nucleus of the diagonal band, the nucleus accumbens and the bed nucleus of the stria terminalis. SRIF neurons and fibers were found in several hypothalamic and anterior thalamic nuclei as well as all regions of the corpus striatum. An interesting collection of SRIF immunoreactive neurons and processes were observed forming a wide band extending anteriorly from the lateral preoptic area through the lateral hypothalamus and substantia innominata posteriorly. This report on the localization of immunoreactive SRIF in the human forebrain extends previous anatomical findings and lends morphological support to recent biochemical studies.     

Distribution of somatostatinlike immunoreactivity in the brain of the little brown bat (Myotis lucifugus)

The distribution of somatostatinlike immunoreactive (SLI) perikarya, axons, and terminals was mapped in subcortical areas of the brain of the little brown bat, Myotis lucifugus, using light microscopic immunocytochemistry. A preponderance of immunoreactivity was localized in reticular, limbic, and hypothalamic areas including: 1) in the forebrain: the bed nucleus of the stria terminalis; lateral preoptic, dorsal, anterior, lateral and posterior hypothalamic areas; amygdaloid, periventricular, arcuate, supraoptic, suprachiasmatic, ventromedial, dorsomedial, paraventricular, lateral and medial mammillary, and lateral septal nuclei; the nucleus of the diagonal band of Broca and nucleus accumbens septi; 2) in the midbrain: the periaqueductal gray, interpeduncular, dorsal and ventral tegmental, pretectal, and Edinger-Westphal nuclei; and 3) in the hindbrain: the superior central and parabrachial nuclei, nucleus incertus, locus coeruleus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammillary and premammillary nuclei, medial and dorsal lateral geniculate nuclei, entopeduncular nucleus, lateral habenular nucleus, central medial thalamic nucleus, central tegmental field, linear and dorsal raphe nuclei, nucleus of Darkschewitsch, superior and inferior colliculi, nucleus ruber, substantia nigra, mesencephalic nucleus of V, inferior olivary nucleus, inferior central nucleus, nucleus prepositus, and deep cerebellar nuclei. While these results were similar in some respects to those previously reported in rodents, they also provided interesting contrasts.     

Pattern of afferents to the lateral septum in the guinea pig

Summary The septal region represents an important telencephalic center integrating neuronal activity of cortical areas with autonomous processes. To support the functional analysis of this brain area in the guinea pig, the afferent connections to the lateral septal nucleus were investigated by the use of iontophoretically applied horseradish peroxidase (HRP). Retrogradely labeled perikarya were located in telencephalic, diencephalic, mesencephalic and metencephalic sites. The subnuclei of the lateral septum (pars dorsalis, intermedia, ventralis, posterior) receive afferents from the (i) medial septal nucleus, diagonal band of Broca (pars horizontalis and pars ventralis), and the principal nucleus of the stria terminalis, the hippocampus, and amygdala (nucleus medialis); (ii) the medial habenular nucleus, and the para- (peri-) ventricular, parataenial and reuniens nuclei of the thalamus; the anterior, lateral and posterior hypothalamic areas in particular, the medial and lateral preoptic, suprachiasmatic, periventricular, paraventricular, arcuate, premammillary, and supramammillary nuclei; (iii) the periaquaeductal grey, ventral tegmental area, nucleus interfascicularis, nucleus reticularis linearis, central linear nucleus, interpeduncular nucleus; (iv) dorsal and medial raphe complex, and locus coeruleus. Each subnucleus of the lateral septum displays an individual, differing pattern of afferents from the above-described regions. Based on a double-labeling method, the vasopressinergic and serotonergic afferents to the lateral septum were found to originate in the nucleus paraventricularis hypothalami and the raphe nuclei, respectively.Abbreviations ARC arcuate nucleus - BNST bed nucleus of the stria terminalis - CL central linear nucleus - DBBh diagonal band of Broca (pars horizontalis) - DBBv diagonal band of Broca (pars ventralis) - DR dorsal raphe nucleus - HC hippocampus - IF interfascicular nucleus - IP interpeduncular nucleus - LC locus coeruleus - LDT laterodorsal tegmental nucleus - LHA lateral hypothalamic area - LPO lateral preoptic area - LSN lateral septal nucleus - MA medial amygdaloid nucleus - MH medial habenular nucleus - MPO medial preoptic region - MR medial raphe nucleus - MSN medial septal nucleus - PAG periaquaeductal grey - PEN periventricular nucleus - PHA posterior hypothalamic area - PMd premammillary region (pars dorsalis) - PMv premammillary region (pars ventralis) - PT parataenial nucleus - PVN paraventricular hypothalamic nucleus - PVT paraventricular thalamic nucleus - RE nucl. reuniens - RL nucl. reticularis linearis - SCN suprachiasmatic nucleus - SMl supramammillary region (pars lateralis) - SMm supramammillary region (pars medialis) - SUB subiculum - TS triangular septal nucleus - VTA ventral tegmental area - ac anterior commissure - bc brachium conjunctivum - bp brachium pontis - cc corpus callosum - fr fasciculus retroflexus - fx fornix - ml medial lemniscus - mlf fasciculus longitudinalis medialis - mp mammillary peduncle - mt mammillary tract - oc optic chiasm - on optic nerve - pc posterior commissure - pt pyramidal tract - sm stria medullaris - st stria terminalis - vhc ventral hippocampal commissure Supported by the Deutsche Forschungsgemeinschaft (Nu 36/2-1)     

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.     

Mesotocin and vasotocin in the brain of the lizard Gekko gecko

Summary The distribution of mesotocin and vasotocin was studied in the brain of the lizard Gekko gecko with antisera specific for either peptide. Both mesotocinergic and vasotocinergic perikarya are found in the paraventricular and supraoptic nuclei of the hypothalamus, whereas vasotocinergic neurons are exclusively present in the bed nucleus of the stria terminalis and in a cell group of the rhombencephalon. The distributional pattern of the mesotocinergic fibers corresponds closely to that of the vasotocinergic fibers. However, throughout the entire brain the mesotocinergic innervation is less dense than the vasotocinergic innervation. No sex differences are present in the mesotocinergic fiber system.Abbreviations acc nucleus accumbens - bst bed nucleus of the stria terminalis - bv blood vessel - dB diagonal band of Broca - dc dorsal cortex - dth dorsolateral thalamic nucleus - lc lateral cortex - me median eminence - oc optic chiasma - ot optic tract - pag periaqueductal grey - pvn paraventricular nucleus - rc rhombencephalic cell group - sep septum - son supraoptic nucleus - tect mesencephalic tectum - vth ventrolateral thalamus     

Light and electron microscopic immunocytochemistry of proenkephalin-derived peptides in septal neurons

Specific antibodies against different opioid peptides derived from proenkephalin were used in light and electron microscopic studies to locate septal enkephalin-containing cells. Immunoreactive neurons were demonstrated only after pretreatment of the animals with colchicine. They were found in all three subdivisions of the lateral septal nucleus and in the ventral limb of the nucleus of the diagonal band. The medial septal nucleus and the dorsal limb of the nucleus of the diagonal band were devoid of immunoreactive cells. Electron microscopy showed intracellular enkephalin-like immunoreactivity with all antisera used in this study. The reaction was found in the cytoplasm, sometimes associated with the rough endoplasmic reticulum. Numerous enkephalin-immunoreactive nerve terminals and fibres were detected in the lateral septal nucleus, but axon terminals making contacts with enkephalin-immunoreactive neurons did not contain enkephalin-like immunoreactivity. The results suggest that some septal neurons synthesise proenkephalin. These cells may be either local interneurons or output cells to areas which receive innervation from the septal complex.     

Distribution of arginine vasotocin in the brain of the lizard Anolis carolinensis

Summary The distribution of immunoreactive arginine vasotocin (AVT-ir) was determined in the brain of the lizard Anolis carolinensis. Cells and fibers containing AVT-ir were found in the medial septal region, lamina terminalis, lateral forebrain bundle, preoptic area, supraoptic nucleus, anterior hypothalamus, paraventricular nucleus, periventricular nucleus, arcuate nucleus, and ventromedial nucleus of the thalamus. Occasional AVT-ir cells were found in the interpeduncular nucleus. Fibers containing AVT-ir were found in the cortex, around the olfactory ventricle, in the diagonal band of Broca, amygdala area, dorsal ventricular ridge, striatum, nucleus accumbens, septum, ventromedial hypothalamus, lateral hypothalamus, medial forebrain bundle, median eminence, pars nervosa, nucleus of the solitary tract, locus coeruleus, cerebellar cortex (granular layer), dorsal part of the nucleus of the lateral lemniscus, substantia nigra, and myelencephalon. The intensity of AVT-ir staining was, in general, greater in males than in females. Comparison of AVT-ir distribution in A. carolinensis with those previously published for other reptilian species revealed species-specific differences in distribution of AVT.     

Peptide immunoreactive neurons in the amygdala and the bed nucleus of the stria terminalis project to the midbrain central gray in the rat.

The central nucleus of the amygdala, bed nucleus of the stria terminalis, and central gray are important components of the neural circuitry responsible for autonomic and behavioral responses to threatening or stressful stimuli. Neurons of the amygdala and bed nucleus of the stria terminalis that project to the midbrain central gray were tested for the presence of peptide immunoreactivity. To accomplish this aim, a combined immunohistochemical and retrograde tracing technique was used. Maximal retrograde labeling was observed in the amygdala and bed nucleus of the stria terminalis after injections of retrograde tracer into the caudal ventrolateral midbrain central gray. The majority of the retrogradely labeled neurons in the amygdala were located in the medial central nucleus, although many neurons were also observed in the lateral subdivision of the central nucleus. Most of the retrogradely labeled neurons in the BST were located in the ventral and posterior lateral subdivisions, although cells were also observed in most other subdivisions. Retrogradely labeled neurotensin, corticotropin releasing factor (CRF), and somatostatin neurons were mainly observed in the lateral central nucleus and the dorsal lateral BST. Retrogradely labeled substance P-immunoreactive cells were found in the medial central nucleus and the posterior and ventral lateral BST. Enkephalin-immunoreactive retrogradely labeled cells were not observed in the amygdala or bed nucleus of the stria terminalis. A few cells in the hypothalamus (paraventricular and lateral hypothalamic nuclei) that project to the central gray also contained CRF and neurotensin immunoreactivity. The results suggest the amygdala and the bed nucleus of the stria terminalis are a major forebrain source of CRF, neurotensin, somatostatin, and substance P terminals in the midbrain central gray.     

Telencephalic sources of the afferents of the main olfactory bulb in the frog Rana temporaria

Following horseradish peroxidase iontophoretic application into the main olfactory bulb (MOB) retrograde neuronal labeling was examined in the telencephalon in the frog. Labeled neurons, the sources of the MOB afferents are found in the mitral cell layer of the contralateral MOB, pallial and some subpallial areas. Very heavy labeling is observed in the pars ventralis of the lateral pallium, and to a lesser extent in the medial pallium, pars dorsalis of the lateral pallium and in the dorsal pallium. In subpallium labeled neurons are found in the eminentia postolfactoria, the rostral part of the medial septal nucleus, and in the nucleus of the ventro-medial telencephalic wall, which is probably homologous to the nucleus of the diagonal band (Broca) of mammals. No labelled neurons were found in the caudal portion of the MOB granular layer, usually referred to as the anterior olfactory nucleus. The arrangement of the MOB centrifugal innervation in amphibians is discussed in comparison with that in mammals.     

Gonadotropin-releasing hormone (GnRH) neurons and pathways in the rat brain

Summary Gonadotropin-releasing hormone (GnRH) neurons and their pathways in the rat brain were localized by immunocytochemistry in 6-to 18-day-old female animals, by use of thick frozen or vibratome sections, and silver-gold intensification of the diaminobenzidine reaction product. GnRH-immunoreactive perikarya were observed in the following regions: olfactory bulb and tubercle, vertical and horizontal limbs of the diagonal band of Broca, medial septum, medial preoptic and suprachiasmatic areas, anterior and lateral hypothalamus, and different regions of the hippocampus (indusium griseum, Ammon's horn). In addition to the known GnRH-pathways (preoptico-terminal, preoptico-infundibular, periventricular), we also observed GnRH-immunopositive processes in several major tracts and areas of the brain, including the medial and cortical amygdaloid complex, stria terminalis, stria medullaris thalami, fasciculus retroflexus, medial forebrain bundle, indusium griseum, stria longitudinalis medialis and lateralis, hippocampus, periaqueductal gray of the mesencephalon, and extracerebral regions, such as the lamina cribrosa, nervus terminalis and its associated ganglia. By use of the silver-gold intensification method we present Golgi-like images of GnRH perikarya and their pathways. The possible distribution of efferents from each GnRH cell group is discussed.     

REGIONAL DISTRIBUTION OF GLUTAMATE DECARBOXYLASE AND GABA WITHIN THE AMYGDALOID COMPLEX AND STRIA TERMINALIS SYSTEM OF THE RAT

The distribution of glutamate decarboxylase (GAD) and δ-amino butyric acid have been studied in the amygdaloid complex and in the stria terminalis system of the rat. The central and medial nuclei of the amygdala had significantly higher activities of GAD than the lateral olfactory tract nucleus, anterior amygdala, anterior lateral nucleus, posterior lateral nucleus, cortical nucleus, basomedial nucleus, basolateral nucleus, and pyriform cortex. The enzyme activity was about two and a half times higher in the central and medial nuclei than in the pyriform cortex. GABA was also significantly more concentratcd in these nuclei than in the pyriform cortex although this was not true for four other amino acids studied–glutamic acid, aspartic acid, taurine and glycine. GAD activity was also measured in the stria terminalis (the major afferent and efferent pathway of the amygdala) and in its bed nucleus. The enzyme activity was higher in the stria terminalis than in four other fibre tracts studied–the optic tract, anterior commissure, corpus callosum, and fimbria. GAD activity was exceptionally high in the bed nucleus of the stria terminalis particularly in its ventral part. The significance of the results are discussed in terms of what is known about the evolution and anatomy of the amygdala.     

Obesity-inducing amygdala lesions: examination of anterograde degeneration and retrograde transport

Small lesions centered in the posterodorsal region of the medial amygdala resulted in excessive weight gains in female rats. Unilateral lesions were nearly as effective as bilateral lesions in the first 48 h after surgery (+21 to +32 g). Assessment of lesion damage was done by both qualitative evaluation and by a quantitative grid-point counting method. The critical sites for weight gain were the intra-amygdaloid bed nucleus of the stria terminalis and the posterodorsal medial amygdaloid nucleus. Incidental damage to the overlying globus pallidus was negatively related to weight gain. The cupric silver method for demonstrating axonal degeneration was applied to brains with obesity-inducing lesions. A dense pattern of degenerating terminals was found in the lateral septum, amygdala, ventral striatum, and ventromedial hypothalamus. Degeneration in the paraventricular nucleus of the hypothalamus was scarce or absent. Small retrograde tracer injections made in either the intra-amygdaloid bed nucleus of the stria terminalis or in the posterodorsal medial amygdaloid nucleus labeled cells in the amygdala, lateral septum, and hypothalamus, reciprocating the anterograde projections from the amygdala to these areas. The data suggest that subdivisions of the posterodorsal amygdala participate in the regulation of feeding in a manner that is similar to the better-known role of this part of the brain in mediating reproductive behavior. Although topographical differences may exist within the amygdaloid and hypothalamic subdivisions regulating these two sexually dimorphic behaviors, the relays engaged by feeding-related connections and those related to reproduction are remarkably parallel.     

Aromatase in axonal processes of early postnatal hypothalamic and limbic areas including the cingulate cortex

It has been shown that sexual dimorphic morphology of certain hypothalamic and limbic areas underlie gender-specific sexual behavior and neuroendocrine mechanisms. The key role played by locally formed estrogen in these developmental events has been revealed during a critical perinatal period. In this study, we aimed to document the presence of estrogen-synthetase (aromatase)-immunoreactive elements in the involved limbic system and hypothalamus of the developing rat brain. On postnatal day 5, animals of both sexes were perfusion-fixed, and sections from the forebrain and hypothalamus were immunolabelled for aromatase using an antiserum that was generated against a 20 amino acid sequence of placental aromatase. Aromatase-immunoreactivity was present in neuronal perikarya and axonal processes in the following limbic structures: the central and medial nuclei of the amygdala, stria terminalis, bed nucleus of the stria terminalis (BNST), lateral septum, medial septum, diagonal band of Broca, lateral habenula and all areas of the limbic (cingulate) cortex. In the hypothalamus, the most robust labelling was observed in the medial preoptic area, periventricular regions, ventromedial and arcuate nuclei. The most striking feature of the immunostaining with this antiserum was its intracellular distribution. In contrast to the heavy perikaryal labelling that can be observed with most of the currently available aromatase antisera, in the present experiments, immunoperoxidase was predominantly localized to axons and axon terminals. All the regions with fiber staining corresponded to the projection fields of neuron populations that have previously been found to express perikaryal aromatase. Our results confirm the presence of aromatase-immunoreactivity in developing limbic and hypothalamic areas. The massive expression of aromatase in axonal processes raises the possibility that estrogen formed locally by aromatase may not only regulate the growth, pathfinding and target recognition of its host neuronal processes, but may also exert paracrine actions on structures in close proximity, including the target cells.     

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.     

前脑生长抑素样神经元对大鼠颈部食管前运动神经元的支配——PRV和SOM荧光双标记法研究

用ＰＲＶ和ＳＯＭ免疫荧光双标记法研究了前脑中ＳＯＭ样神经元对孤束核中食管前运动神经元的支配。当ＰＲＶ注射于大鼠颈部食管后,在大脑皮质前部嗅沟背侧的无颗粒型岛叶皮质后部和嗅沟腹侧的梨状前皮质前部可见较多ＰＲＶ和ＳＯＭ双标记细胞。在终纹床核、内侧视前区、外侧视前区和正中视前区、终板血管器、穹隆下器、以及嗅结节等处也可见少量ＰＲＶ和ＳＯＭ双标记细胞。本文推测脑对颈部食管运动的调节是由广泛的中枢神经系统结构来完成的     

Demonstration of distinct corticotropin releasing factor--containing neuron populations in the bed nucleus of the stria terminalis. A light and electron microscopic immunocytochemical study in the rat

Immunocytochemical light and electron microscopic studies revealed two distinct populations of corticotropin releasing factor (CRF) - containing neurons, a dorsolateral and ventrolateral group, located in the bed nucleus of the stria terminalis (BST) of the rat brain. CRF neurons of the dorsolateral group had a smaller diameter and more primary dendrites than those of the ventrolateral group. CRF neurons in the dorsolateral BST had both somatic and dendritic spines, smooth contoured nuclei, and many dense and alveolate vesicles in their cytoplasm. Whereas, CRF neurons in the ventrolateral BST had only dendritic spines, irregularly-shaped indented nuclei and contained only alveolate vesicles in their cytoplasm. The only obvious difference in the type of unidentified afferents that synapsed on the CRF neurons of the BST could be attributed to the presence of the somatic spines on the CRF neurons of the dorsolateral population. Otherwise, the CRF neurons of the BST had a profuse innervation that included axosomatic, axospinous and axodendritic synapses. CRF-containing axons were distributed unevenly throughout the BST. The density of CRF axons was greatest in the lateral subdivisions of the BST, but the ventromedial BST contained many more CRF axons than the dorsomedial BST. The presence of these two CRF neuron populations in the BST suggests functional subdivision beyond previous proposals of a medial and lateral separation of function. Now there is additional morphological evidence to support the proposal of a dorsal and ventral separation of function within the BST.     

Distribution of gastrin-releasing peptide immunoreactivity in the brain of the collared dove (Streptopelia decaocto)

The distribution of immunoreactivity after applying an antibody against gastrin-releasing peptide (GRP) was studied in the brain of the collared dove (Streptopelia decaocto). In the forebrain GRP-immunoreactive (GRP-ir) cells were found in the hyperstriatum accessorium, medial and lateral parts of the neostriatum, corticoidea dorsolateralis and temporoparieto-occipitalis areas, hippocampus, pre- and parahippocampal areas and prepiriform cortex. In the brainstem, GRP-ir cells were restricted mainly to the substantia nigra and ventral tegmental nucleus. Areas with densely packed GRP-ir clusters of varicosities were the medial intermediate hyperstriatum ventrale and lateral septal nucleus; dense GRP-ir neuropil was found in the parolfactory lobe, and in the dorsal half of the intermediate and caudal archistriatum. The ventral lamina medullaris contained many GRP-ir fibers. Forebrain areas devoid of immunoreactivity were the basal nucleus, ectostriatum, rostral archistriatum, most of the paleostriatum augmentatum and the lateral bed nucleus of the stria terminalis. Moderate densities of GRP-ir elements were found in the other telencephalic areas and further in, among others, the preoptic and hypothalamic region, ventral area of Tsai, cerulean nuclei, parabrachial complex, dorsal glossopharyngeal and vagus motor nuclei and medial nuclei of the solitary complex. The observations are compared with data from the literature and the implications for the definition of specific centers within the avian brain are discussed, with emphasis on systems with a role in visceral and motivational functions and in learning.     

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.