The extravascular channel system in the rostral pituitary of Mugil cephalus (Teleostei) as revealed by use of horseradish peroxidase

Summary Using the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the light microscopic level, it was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. A tendency to preferential location of the two kinds of neuronal perikarya is described. The neurosecretory perikarya are the origin of separate vasotocinergic and mesotocinergic axons. In the neural lobe, the pattern of distribution of the two types of axons is different. The coarse ventricular dendrites of both kinds of neurons are hormone-containing processes. Staining with anti-bovine neurophysin I serum suggested that the vasotocinergic and the mesotocinergic neurons synthesize different neurophysins.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

Immunohistochemical demonstration of alpha-1-antitrypsin in the islet cells of human pancreas

Summary Using the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique at the light microscopic level, it has been shown that, in the dipnoan preoptico-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. In the preoptic nuclei, the perikarya of these two types of neurosecretory neurons are not located preferentially. The two types of neurosecretory perikarya give rise to separate vasotocinergic and mesotocinergic axons, respectively. The dipnoan median eminence and neural lobe contain separate vasotocinergic and mesotocinergic nerve fibres, the general distribution of which is described. In the pars distalis and the pars intermedia of the hypophysis, neurohypophysial hormone-containing nerve fibres have not been found.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk OnderzoekThe authors are greatly indebted to Prof. Dr. Hyder, Department of Zoology, University of Nairobi, Kenya for kindly supplying us with the fixed material used in this study     

Immunocytochemical study of the hypothalamo-neurohypophysial system

Summary Antisera, with cross reactive antibodies removed by affinity chromatography, were used in the immunoperoxidase-bridge technique to study the distribution of oxytocin and vasopressin together with neurophysin in the hypothalamo-neurohypophysial system of the rat. The hormones were demonstrated in different areas of the supraoptic nucleus (SON) and paraventricular nucleus (PVN), in neurosecretory fibres of the hypothalamoneurohypophysial tract, median eminence, and in nerve terminals of the neurohypophysis. Intact normal and rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain), and rats dehydrated by the administration of oral hypertonic saline were studied. In dehydrated rats the hormone concentration in the neurons, and the number of neurons containing hormone varied according to the time of dehydration stress.The observations support the hypotheses that: 1) oxytocin and oxytocinneurophysin, and vasopressin and vasopressin-neurophysin are synthesised in different neurons and are transported along different axons; 2) the SON and PVN are functionally indistinguishable in that neurons containing oxytocin or vasopressin are present in both nuclei; and 3) the two types of neurons respond to osmotic stimulation in a way that is qualitatively the same but quantitatively different.This work was supported by a grant from the Medical Research Council of New Zealand     

Immunocytochemical identification of dynorphin-containing vesicles in Brattleboro rats

Vasopressin and its carrier protein, vasopressin-associated neurophysin, are co-packaged together with an opioid peptide, dynorphin, into 160 nm diameter neurosecretory vesicles in the normal rat hypothalamo-neurohypophysial system. The homozygous Brattleboro rat lacks vasopressin and vasopressin-associated neurophysin, but contains substantial amounts of dynorphin in the vasopressin-deficient neurosecretory cells. We used post-embedding electron microscopic immunocytochemistry to determine the subcellular location of dynorphin in Brattleboro rats. The results show that dynorphin is present within 100 nm neurosecretory vesicles in homozygous Brattleboro cell bodies and axons, and within 160 nm vesicles in heterozygous (control) neurosecretory cell bodies and axons. Oxytocin-associated neurophysin is present in a separate population of magnocellular neurons in both homozygous and heterozygous rats, and is contained within 160 nm vesicles in both cases. Therefore, the absence of synthesis of the vasopressin prohormone results in a dramatic reduction of neurosecretory vesicle size, despite the continued synthesis and packaging of dynorphin peptides.     

Coexisting peptides in hypothalamic neuroendocrine systems: Some functional implications

1. Coexisting with oxytocin or vasopressin in the cell bodies and nerve terminals of the hypothalamic-neurohypophysial system are smaller amounts of other peptides. For a number of these "copeptides" there is strong evidence of corelease with the major magnocellular hormones. Guided by the location of their specific receptors we have studied the effects of three copeptides, dynorphin, cholecystokinin (CCK), and corticotropin releasing hormone (CRH), on the secretion of oxytocin and vasopressin from isolated rat neural lobe or neurointermediate lobe preparations in vitro. 2. Dynorphin is coreleased with vasopressin from neural lobe nerve terminals and acts on neural lobe kappa-opiate receptors to inhibit the electrically stimulated secretion of oxytocin. Naloxone augments oxytocin release from the neural lobe in a manner directly proportional to the amount of vasopressin (and presumably dynorphin) released. 3. Cholecystokinin, coreleased with oxytocin by neural lobe terminals, has been shown to have high-affinity receptors located in the NL and to stimulate secretion of both oxytocin and vasopressin. CCK's secretagogue effect was independent of electrical stimulation and extracellular Ca2+ and was blocked by an inhibitor of protein kinase C. 4. CRH, coreleased with OT from the neural lobe, has receptors in the intermediate lobe of the pituitary, but not in the neural lobe itself. CRH stimulates the secretion of oxytocin and vasopressin from combined neurointermediate lobes but not from isolated neural lobes. Intermediate lobe peptides, alpha and gamma melanocyte stimulating hormone, induced secretion of oxytocin and vasopressin from isolated neural lobes. Their effect was, like that of CCK, independent of electrical stimulation and extracellular Ca2+ and blocked by an inhibitor of protein kinase C. 5. Among the CRH-producing parvocellular neurons of the paraventricular nucleus, in the normal rat, approximately half also produce and store vasopressin. After removal of glucocorticoid influence by adrenalectomy, virtually all of the CRH neurons contain vasopressin. 6. The two subtypes of CRH neurosecretory cells found in the normal rat possess different topographical distributions in the paraventricular nucleus, suggesting the possibility of differential innervation. Stress selectively activates the vasopressin containing subpopulation of CRH neurons, indicating that there are separate channels of regulatory input controlling the two components of the parvocellular CRH neurosecretory system.     

Ultrastructural studies on the localization of neurohypophysial hormones and their carrier proteins.

Neurophysin, vasopressin and oxytocin were localized in different portions of the supraopticohypophysial tract (SHT) using the unlabeled antibody enzyme technique at the ultrastructural level. In vasopressin-positive supraoptic perikarya, vasopressin and neurophysin were present in all neurosecretory granules. Within the zona interna of the median eminence, vasopressin and neurophysin were present in two populations of axons, one with granules of 1300-1500 A and one with granules of 900-1300 A. Following exposure of thin sections of median eminence to antiserum to neurophysin, reaction products were present in granules and in the extragranular cytoplasm in the axons with larger granules; in all other cases reaction product was confined to the granules. Vasopressin-positive fibers were also presented in large numbers of the zona externa of the median eminence and many terminated on the pituitary primary portal plexus. A few oxytocin fibers were present on the portal capillaries in the infundibular stalk. In the posterior pituitary all axon profiles were neurophysin positive. Neurophysin was present as both a granular and cytoplasmic pool. Vasopressin-containing axons account for 90% of the neuronal elements in the posterior pituitary and oxytocin for the remaining 10%. Findings on the subcellular distribution of these peptides are related to current theories on transport and release of neurohormones.     

Immunocytochemical evidence for the presence of a mutant vasopressin precursor in the supraoptic nucleus of the homozygous Brattleboro rat

Summary CP-14, a tetradecapeptide from the predicted mutant vasopressin precursor in the homozygous Brattleboro rat was detected immunocytochemically in the supraoptic nucleus of homozygous Brattleboro but not normal rats. The staining was localized to the periphery of the perikarya. CP-14 immunoreactivity was not found in the neural lobes, paraventricular nuclei, accessory nuclei or suprachiasmatic nuclei of either homozygous Brattleboro or normal rats. Vasopressin immunoreactivity was found in the neural lobe and in the perinuclear region of neurons of the supraoptic, paraventricular, suprachiasmatic and accessory nuclei of normal rats. Vasopressin immunoreactivity was also found in homozygous Brattleboro rats, mainly in the ventral part of the supraoptic nucleus: densely stained solitary cells were found amongst other faintly stained perikarya. In both cell-types the staining was mainly in the periphery of the perikarya. No vasopressin immunoreactivity was detected in the paraventricular nuclei, suprachiasmatic nuclei, accessory nuclei or neural lobe of homozygous Brattleboro rats.CP-14 and vasopressin immunoreactivities were found to be co-localized; both were present in the periphery of the same perikarya of the supraoptic nuclei of homozygous Brattleboro rats. Differential staining was found with antioxytocin serum in both normal rats and homozygous Brattleboro rats: separate neurons were stained for either oxytocin or vasopressin and CP-14. Immunoreactive oxytocin was found mainly in the perinuclear region of the neurons from the supraoptic, paraventricular and accessory nuclei.     

The activated hypothalamic magnocellular neurosecretory system and the one neuron -one neurohypophysial hormone concept

Summary The activated hypothalamic magnocellular neurosecretory system of the rat was studied in tissue sections, double stained with the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique. The results indicate that in animals with an activated hypothalamic magnocellular neuroendocrine system, as well as in normal animals, vasopressin and oxytocin are exclusively synthesized in separate vasopressinergic and oxytocinergic neurons.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

LRF producing cells of the mammalian hypothalamus

Summary The demonstration of perikarya of mediocellular neurones producing LRF, using indirect immunofluorescence on slides and anti synthetic LRF antibodies, requires both their activation and the inhibition of their axoplasmic transport. This fact suggests that LRF is present in an immunoreactive form, but usually in very low concentrations. Perikarya of neurons producing LRF are found principally in the preoptic and septal areas of the rat and decrease caudally, particularly beyond the retrochiasmatic area. Most of the axons coming from these perikarya are incorporated in the hypothalamoinfundibular tract and terminate around the capillaries of the primary portal plexus, particularly those of interealar plexus. Other axons (or axon collaterals) may be found in various areas (suprachiasmal crista, epithalamus, amygdala, mesencephalon) and form circuits recalling the “extrahypophyseal pathways” described for the magnocellular Gomori-positive neurons of the SON and PVN. These axons are probably concerned in intersegmental regulations involving “neurosecretory synapses”, particularly of the axosomatic type. The placement of stereotaxic lesions was used to determine the topography and direction of axoplasmic flow of the axons transporting LRF. The infundibular immunoreactive material, already discernible at the end of gestation in the foetus, shows considerable variations between birth and puberty, during the estrous cycle and under various other physiological or experimental conditions. The observations made under various experimental or physiological conditions suggest that, in the guinea-pig in particular, the greater part of the hypothalamic immunoreactive material is concentrated in the infundibular area. This area of accumulation is comparable to the distal neurohypophysis of the Gomori-positive neurosecretory system coming from the SON and PVN. This work was financed by the D.G.R.S.T. Contract No. 72-7-0375.     

Coexistence of NADPH-diaphorase with vasopressin and oxytocin in the hypothalamic magnocellular neurosecretory nuclei of the rat

Coexistence of NADPH-diaphorase with vasopressin and oxytocin was studied in the magnocellular neurosecretory nuclei of the rat hypothalamus by use of sequential histochemical and immunocytochemical techniques in the same sections. Coexistence was found in all the nuclei examined (supraoptic, paraventricular, circular, fornical, and in some isolated neurons located in the hypothalamic area between the paraventricular and supraoptic nuclei). The ratios of neurons expressing both markers (NADPH-diaphorase and vasopressin, NADPH-diaphorase and oxytocin) in each of the nuclei were very similar. Although further studies must be carried out, the partial coexistence found in all nuclei suggests that NADPH-diaphorase is probably not related to general mechanisms involving vasopressin and oxytocin, but rather in specific functions shared by certain hypothalamic neuronal cell populations.     

The distribution of vasopressin-, oxytocin-, and neurophysin-producing neurons in the guinea pig brain

Summary The location, cytology and projections of vasopressin-, oxytocin-, and neurophysin-producing neurons in the guinea pig were investigated using specific antisera against vasopressin, oxytocin or neurophysin in the unlabeled antibody enzyme immunoperoxidase method. Light microscopic examination of the neurons of the supraoptic and paraventricular nuclei shows that hormone is transported not only in axons, but also in processes having the characteristics of dendrites. Neurons were found to contain only vasopressin or oxytocin; all neurons containing neurophysin appear to contain either vasopressin or oxytocin. In the neural lobe, vasopressin and oxytocin terminals are intermingled. In the median eminence, vasopressin and oxytocin fibers are intermingled in the internal zone. In a caudal portion of the median eminence, a number of vasopressin and neurophysin (but few oxytocin) axons enter the external zone from the internal zone, and surround portal capillaries. In the supraoptic nucleus, vasopressin neurons outnumber oxytocin neurons with a ratio of at least 5:1. The paraventricular nucleus is separated into two distinct groups of neurons, a lateral group consisting of only vasopressin neurons, and a medial group consisting of only oxytocin neurons. In addition to axons passing to the neurohypophysis, a number of axons appear to interconnect the supraoptic and paraventricular nuclei.Supported by the Deutsche Forschungsgemeinschaft (SFB 51, C/21 and C/27), (We 608/3)Acknowledgements. The authors are greatly indebted to Mmes. R. Köpp-Eckmann, B. Reijerman, A. Scheiber, I. Wild and Mr. U. Schrell for technical assistance, to Mmes. P. Campbell and U. Wolf for editorial assistance, and to Dr. R.R. Dries and Ferring Pharmaceuticals, Kiel, for the generous provision of high quality peptides     

Effect of colchicine on vasopressin and melanin-concentrating hormone neurons of rat hypothalamus: hybridocytochemistry and immunocytochemistry studies]

48 hrs. after an intra-cerebroventricular injection of colchicine (100 micrograms), antisera to three putative peptides included in the rat melanin-concentrating hormone (MCH) precursor, strongly stained the secretory granules accumulated in perikarya. In control rats, these antisera stained endoplasmic reticulum, Golgi apparatus, or neurosecretory granules respectively. Colchicine also induced a dramatic decrease in hybridization signal obtained with a probe complementary to the prepro-MCH-mRNA. Similarly, colchicine induced a strong increase in vasopressin immunoreactivity in neurons of the paraventricular and supraoptic nuclei, and a strong decrease of the vasopressin precursor mRNA. These results demonstrated that, in two peptidergic neuron populations of the rat hypothalamus, colchicine lowers mRNAs and impairs neuropeptide protein synthesis, consecutively to the accumulation of neurosecretory granules in perikarya.     

Electron microscopic immunocytochemical investigation on the postnatal development of the vasopressin system in the rat

Summary The present ultrastructural results indicate that, in the rat, the vasopressin-synthesizing perikarya of the supraoptic nucleus (NSO) attain a certain degree of maturity earlier than those of the paraventricular nucleus (NPV). In the neonate rat, the stainability of the nuclear areas is very weak; in the perikarya of the NSO a few labeled granules can be found, whereas the perikarya of the NPV often display only a labeled Golgi area, the cytoplasm being devoid of granules. At the end of the first (NSO) and the second (NPV) postnatal weeks, the filling of the neurosecretory granules with vasopressin is inhomogeneous with irregular spots of reaction product distributed on the granules. This feature is less obvious during the following week and has nearly disappeared after the third and fourth postnatal weeks. Already in the neonate two types of vasopressin-positive fibers are observed in the median eminence, characterized by the different diameters of their granules and by their typical location in the internal and the external pericapillary contact zone. Especially in one and two week-old animals, in the internal zone of the median eminence and, to a lesser degree in the neural lobe, the immunocytochemical reaction product is deposited on an axonal tubular network. Judging from the presence of very few vasopressin-negative fibers in the neural lobe of the neonate, the development of the oxytocin system appears to be delayed. A characteristic relationship between pituicytes and the neurosecretory fibers can be observed during the first two postnatal weeks. After the third postnatal week the immunocytochemical features of the vasopressin system correspond approximately to that in adult rats.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/3) and Stiftung Volkswagenwerk     

Immunohistochemical localization of urotensin I and other neuropeptides in the caudal neurosecretory system of three species of teleosts and two species of elasmobranchs

Summary In three species of teleosts — carp Cyprinus carpio; grass carp Ctenopharyngodon idella; and crucian carp Carassius auratus — the caudal neurosecretory system displays small, medium-sized and large neurons. Urotensin I (UI)-immunoreactive and UI-nonreactive neurons were found in all three groups; in general, the number of the latter neurons exceeded that of the former. Noteworthy are: (i) UI-immunoreactive fibers in the caudal spinal cord and (ii) dense accumulations of UI-immunoreactive product around the capillaries of the urophysis. In two species of elasmobranchs — cat shark Heterodontus japonicas and swell shark Cephaloscyllium umbratile — neurosecretory neurons decreased in size in rostro-caudal direction. Most of the neurosecretory perikarya, their axons and the corresponding neurohemal areas were UI-immunoreactive, but a small number of secretory neurons was devoid of immunoreaction. Oxytocin, arginine vasopressin, substance P, somatostatin, neurotensin, vasoactive intestinal polypeptide and gastrin-releasing peptide were not detected in the caudal neurosecretory system of the carp.     

Granulolysis in neurosecretory neurons of the rat supraoptico-posthypophyseal system

Ultrastructural and cytochemical observations on neurosecretory neurons of the rat supraoptico-posthypophyseal systems were made under experimental conditions which resulted in striking changes in the amount of neurosecretory granules and lysosomes. Attention was focused on granulolysis. At the onset of rehydration following a 4 days water deprivation, very active autophagy took place in neurosecretory axons of the neural lobe involving the marked increase in smooth endoplasmic reticulum, microvesicles and neurosecretory granules, although the latter were still very few due to previous depletion. When axonal transport was inhibited by colchicine at the onset of rehydration, granules accumulated in the perikarya while granule reloading of the neural lobe was delayed. However autophagy, although always active in axons, remained scarce in perikarya. Moreover, in the latter there was only slight evidence of crinophagy. Hypophysectomy also induced granule accumulation in the perikarya, although accompanied by little granulolysis. Images indicative of crinophagy as shown by acid phosphatase localization were few and exclusively restricted to perikarya, while autophagy occurred essentially in axons. Autophagy appeared to be the predominant process for granulolysis and might be considered here as an aspect of the general turnover of cell constituents, related to the sudden regression of hyperactivity-induced hyperthrophy, rather than as an expression of a specific regulation of an excess of secretory material.     

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.     

Ultrastructure of the peptidergic and monoaminergic neurons in the hypothalamic neurosecretory system of Anuran Batracians

Summary In the toad Bufo arenarum Hensel the following regions of the hypothalamic — neurohypophyseal system were studied under the electronmicroscope: preoptic and paraventricular nuclei, median eminence and infundibular process of the neurohypophysis.Neuronal perikarya of the preoptic nucleus are loaded with typical neurosecretory granules of peptidergic nature having a mean diameter of 1660 Å. While most neurons of the winter toad are in a storage stage a few show signs of a more active synthetic activity. A distinctive feature of preoptic neurons is the presence of large lipid droplets. The paraventricular nucleus contains small neurons containing granulated vesicles with a mean diameter of 800-1000 Å. In the region extending between these two nuclei and the median eminence axons containing either neurosecretory elementary granules or granulated vesicles are observed.The inner zone of the median eminence is occupied by axons of the preoptic neurohypophyseal tract; two types of axons, according to the size and density of the neurosecretory granules, may be recognized. The outer zone of the median eminence contains mainly axons and nerve terminals containing granulated vesicles of probable monoaminergic nature and only a few with granules of peptidergic type.The neurohypophysis contains two kinds of axons: one with more dense granules of 1800 Å and the other with granules of lesser electron density and 2100 Å. At the ending proper small clear vesicles of synaptic type are found.A progressive increase in volume of the peptidergic granules along the axon is demonstrated. This is of the order of 218% from the preoptic perikarya down to the infundibular process. The physiological significance of the two neurosecretory systems — i.e. the monoaminergic and the peptidergic — and the probable nature of the two types of peptidergic axons is discussed.Supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas and by the Air Force Office of Scientific Research (AF-AFOSR 963-67).The authors want to express their gratitude to Mrs. Defilippi-Novoa and Mr. Alberto Sáenz for their skillful assistance.     

Immunohistochemical investigation of neuropeptides in the central nervous system of the amphioxus,Branchiostoma belcheri

The immunohistochemical localization of nine different neuropeptides was studied in the central nervous system of the amphioxus, Branchiostoma belcheri. In the brain, perikarya immunoreactive for urotensin I and FMRFamide were localized in the vicinity of the central canal. One of the processes of each of these perikarya was found to cross the dorso ventral slit-like lumen of the central canal. Oxytocin-immunoreactive short fibers, but not perikarya, were detected in the ventral part of the brain. Perikarya immunoreactive for arginine vasopressin/vasotocin, oxytocin and FMRFamide were widely distributed in the spinal cord. Arginine vasopressin/vasotocin-immunoreactive fibers often made contacts with Rohde cell axons. Angiotensin II-immunoreactive perikarya were observed in the posterior half of the spinal cord, and urotensin I-immunoreactive perikarya were found in the caudal region of the spinal cord. Cholecystokinin/gastrin-immunoreactive fibers, but not perikarya, were detected in the spinal cord; some extended as far as the ependymal layer of the cerebral ventricle. No colocalization of the peptides examined was observed. No immunoreactivity for atrial and brain natriuretic peptides nor for urotensin II was detected. The present study indicates that there are at least six separate neuronal systems that contain different peptides, respectively, in the central nervous system of the amphioxus. Their functions remain to be determined.Part of this investigation has previously been presented in abstract form (Uemura et al. 1989)     

Axonal projections within the brain-retrocerebral complex of the cricket,Teleogryllus commodus

Summary The cerebral origins and axonal trajectories of neurons projecting to the retrocerebral complex of the cricket, Teleogryllus commodus, were examined in silver-intensified nickel preparations. Spatially separate groups of somata in the pars intercerebralis (PI) and in the pars lateralis (PL), commonly accepted as neurosecretory loci, were found to give rise to axons which terminate in the nervus corporis allati 2, the corpus allatum, or the corpus cardiacum. Additional findings demonstrated a distinct group of somata from the PI whose axons run in the esophageal nerve (stomatogastric nervous system), nine somata in the subesophageal ganglion with axons projecting into the nervus corporis allati 2, and also a small cluster of tritocerebral perikarya with axons terminating in the corpus cardiacum. Somata residing in the PI and PL were found to be compartmentally organized based upon the retrocerebral destinations of their axons. Possible functional consequences of these results with respect to the insect neurosecretory system are discussed.     

Immuno-cytochemical demonstration of the inability of the homozygous Brattleboro rat to synthesize vasopressin and vasopressin-associated neurophysin

Summary Immuno-enzyme cytochemical investigations have shown that, (1) the hypothalamic supraoptic and paraventricular nuclei of the Brattleboro rat, as in the normal rat, contain separate neurons which produce oxytocin + neurophysin; (2) the hereditary inability of the Brattleboro rat to synthesize vasopressin and its associated neurophysin is due to a biochemical defect of separate neurophysin-vasopressin neurons in the supraoptic and the paraventricular nuclei. These observations strongly support the hypotheses that (1) vasopressin and its associated neurophysin are formed via a common precursor, and (2) the initial point of intracellular appearance of the hereditary defect in the Brattleboro rat lies in the synthesis of this precursor, which occurs on ribosomes.Moreover, observations have demonstrated that, in the Brattleboro rat, in addition to the hereditary inability of the hypothalamic magnocellular neurosecretory system to synthesize vasopressin, there also exists a similar hereditary defect in the hypothetical parvicellular suprachiasmatic-median eminence neurosecretory system.This paper is dedicated to Professor Dr. W. Bargmann, in honour of his 70th birthday.Presented in part at the meeting of the Belgian Society of Endocrinology May 17, 1975 (Vandesande et al., 1975d).