Neurosecretory Material Research Articles

Some aspects of activity regulation of Galleria mellonella PTTH cells

AbstractUsing the Galleria prothoracicotropic bioassay, five small neurosecretory cells occurring in each dorsolateral part of protocerebrum of Galleria mellonella brain were identified as prothoracicotropic hormone (PTTH) cells. It was found that the critical period for the release of PTTH from a brain implanted in neck‐ligated larva lasts up to the third day after implantation. The content of paraldehyde‐fuchsin positive neurosecretory material (NSM) in PTTH cells was determined during the penultimate and last larval instar, during pupal instar, and in starved or poststarvation fed or space‐deprived last instar larvae. Two peaks of NSM in PTTH cells were found in the penultimate instar (in freshly molted, and 76‐h‐old larvae), four peaks in the last instar larvae (in freshly molted, and in 67‐, 132‐, and 174‐h‐old larvae), and one peak in the pupal instar (in 56‐76‐h‐old pupae). It was also observed that upon starvation NSM accumulated in PTTH cells, while after 3 h of poststarvation feeding it was released. In permanent space‐deprived last instar larvae no NSM occurred in PTTH cells. In all investigated larval instars a rapid release of NSM from PTTH cells was found a few hours after molt associated with the beginning of the feeding period. The significance of the NSM content in PTTH cells is discussed in relation to ecdysteroid titer.

Ultrastructural changes in isolated peptidergic nerve terminals induced by digitonin permeabilization and K+ stimulation in the sinus gland of the crab, Cardisoma carnifex.

The preparation of isolated peptidergic nerve terminals from the sinus gland (a neurohemal organ) of the crab (Cardisoma carnifex) is described. In this species the nerve endings can have diameters up to 30 microns. They release neurosecretory material as judged by the decrease in the volumetric density of granules upon depolarization with potassium. Similar results were obtained after permeabilization of the nerve terminals with digitonin, but only in the presence of micromolar concentrations of calcium. This preparation should prove useful in correlating electrical events with other cellular processes involved in stimulus-secretion coupling.

Mise en évidence de peptides apparentés à la vasopressine et à l'ocytocine dans le cerveau de l'Hirudinée rhynchobdelle Theromyzon tessulatum (O.F.M.)

Vasopressin- and oxytocin-immunoreactive cells have been demonstrated in the brain of the leech Theromyzon tessulatum. A mapping of their localization in the different compartments of the brain has been undertaken. The cells immunohistochemically identified have been compared to previously described cell types defined by classical staining methods for neurosecretory material. Preliminary results obtained with high performance liquid chromatography confirm the presence in brain homogenates of substances with chromatographic properties similar to that of vertebrate nonapeptides. The possible role of these vasopressin- and oxytocin-like substances in osmoregulation is discussed.

Cytophysiological study of neurosecretory and pheromonal influences on sexual development inOphryotrocha puerilis(Polychaeta, Dorvilleidae)

Summary Prominent secretory nerve endings are found at the posterior margin of the supraesophageal ganglion in the protandric polychaete, Ophryotrocha puerilis. Solitary juveniles developing as primary males, and then as females, accumulate neurosecretory material in the nerve endings which thereby swell and become filled with granules. Females maintained in mass culture have similar terminals, whereas in secondary males (males which had been females before), these axon terminals are very small and contain no material. When such males are isolated, they accumulate neurosecretory material within the nerve endings and become females. When formerly isolated females are put together, their stores of neurosecretory material are rapidly discharged. Subsequently they lay egg masses and switch to the male state. These effects are mediated by a pheromone released during social contact of formerly isolated females. The complexity of the relationship between neurosecretory activity and sexual state is indicated by t...

Effect of juvenile hormone (III) from the hostApis mellifera (Insecta: Hymenoptera) on the neurosecretion of the parasitic miteVarroa jacobsoni (Acari: Mesostigmata)

In the parasitic bee miteVarroa jacobsoni neurosecretory material of ten different cell groups in the synganglion was examined by victoria blue staining after oxidation. Important periods in the life of the mite correspond to definite patterns of filling in of the neurosecretory cell groups. Material of cell group 1, which is situated in the medial protocerebral area of the synganglion, supports molting and oviposition. Secretion of cell group 2, which lies between the two ganglionic masses, seems to be necessary during the whole reproductive process. Cell group 8, located at the opisthosomal ganglion where the genital nerves leave the subesophageal ganglion, seems to be mainly responsible for the initiation of reproduction. Juvenile hormone (JHIII) in the hemolymph of the bees acts on the mites as a release mechanism for reproductive behavior with entry into the brood cell of the bee. Mites on bees with a low JHIII titer that are sprayed with external JHIII show a similar neurosecretion pattern to mites parasitizing bees with a high JHIII titer. The influence of external JHIII on the degree in which the three cell groups are filled with neurosecretion is discussed with respect to the regulatory mechanisms. In this parasite-host relationship there is a clear synchronization of the reproductive cycle of the mite with the metamorphosis and hormonal regulation of the bee.

Neurohypophyseal hormone release and biosynthesis in rats with lesions of the anteroventral third ventricle (AV3V) region.

Lesions of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) have been shown to disrupt body fluid homeostasis. The acute post-lesion phase in rats is characterized by adipsia, the lack of an appropriate antidiuretic response, and plasma vasopressin levels which do not rise. Electron micrographs of the supraoptic nucleus and neural lobe of lesioned adipsic rats suggest no stimulation of biosynthetic activity, and large stores of neurosecretory material in the axon terminals. To directly investigate the status of these neurons, we determined neural lobe vasopressin and oxytocin content and the incorporation of [35S]cysteine into hypothalamic proteins in rats with sham-lesions or lesions of the AV3V after 3 days of adipsia or water deprivation, and in water replete sham-lesioned rats. The results demonstrate that adipsic rats with AV3V lesions have neural lobe vasopressin and oxytocin content equivalent to water-replete sham-lesioned rats. Neural lobe vasopressin and oxytocin levels of water-deprived sham-lesioned rats were significantly below those of all other groups. In addition, this group had a radioactivity incorporation rate into hypothalamic proteins which was two-fold greater than either of the other groups. The results indicate that 3-day adipsic AV3V-lesioned rats do not increase neurohypophyseal hormone release or biosynthesis as do 3-day water-deprived sham-lesioned rats. The periventricular tissue of the AV3V would therefore appear to be crucial in providing information to the hypothalamo-neurohypophyseal neurons on body fluid homeostasis.

The hypothalamo-hypophyseal system of Rana temporaria under osmotic stimulation with special reference to the hypothalamo-median eminence-distal lobe axis

1. 1. The secretory activity of the hypothalamo-hypophyseal system in the frog Rana temporaria under conditions of dehydration has been studied histologically using two parameters, the amount of stained neurosecretory material and the amount of neurosecretory material labelled by a radioactive precursor. 2. 2. The results are indicative of an increased secretory activity of the hypothalamo-neural lobe system as a result of water deprivation. In addition the involvement of the preoptic nucleus-median eminence axis in osmoregulation is confirmed. 3. 3. The pattern of distribution of autoradiographic silver grains over the median eminence together with data from literature support the idea that mesotocine is involved in the regulation of the activity of the adenohypophysis.

Changes in Magnocellular-Neurohypophyseal Vasopressin Following Anteroventral Third-Ventricle (AV3V) Lesions

Lesions of the brain region surrounding the anteroventral third ventricle (AV3V) have been shown to result in adipsia without a corresponding antidiuretic response or rise in plasma vasopressin levels. Electron microscopic examination of the supraoptic nucleus and neural lobe of the pituitary has shown that large stores of neurosecretory material build up in the neurohypophysis. In the present study, the increased neurosecretory material was characterized by immunocytochemistry. Vasopressin immunoreactivity was examined and compared between adipsic rats with AV3V lesions, water-deprived rats, and normal rats. Two days after surgery, sham-lesioned, water-deprived rats displayed decreased vasopressin immunostaining density compared to normal controls, and adipsic AV3V-lesioned rats displayed increased vasopressin immunoreactivity throughout the magnocellular-hypophyseal system. These results indicate that AV3V lesions interrupt neural inputs that stimulate the magnocellular system to release vasopressin in response to normal humoral stimuli.

Relationship between neurosecretion and spermatogenesis in the leech, Erpobdella lineata

1. 1. The central nervous system in the leech, Erpobdella lineata, consists of 21 pairs of cell compartments. 2. 2.AF (aldehyde fuchsin) positive α-cells were observed in the buccal ganglion, cell compartment 8 or 9 and the subesophageal ganglion, cell compartment 11. 3. 3. The cytoplasm of α-cells in cell compartment 11 stained markedly with AF in winter but stained slightly from spring to early autumn. 4. 4. Germ cells in the testes developed actively from spring to early autumn but they scarcely advanced in winter. 5. 5. It is suggested that the neurosecretory materials accumulated in the cytoplasm of α-cells during winter are released from the cell and act on the testes to promote spermatogenesis from spring to early autumn.

Effects of two tranquilizers, reserpine and chlorpromazine, on neurosecretory cells and the ovary of the fiddler crab, Uca pugilator

1. 1. Reserpine produced alterations in neurosecretory cell types I and II in the eyestalk, brain, and thoracic ganglion, most notably a decrease in the amount of stored neurosecretory material. 2. 2. The ovarian index decreased, but the oocyte area increased in the reserpinized crabs. 3. 3. Chlorpromazine did not produce any significant changes in the structure of cell types I and II. In spite of having a normal area, the oocytes in the chlorpromazine injected crabs were devoid of yolk. 4. 4. Neurosecretory cell type III showed no change.

Ultrastructural immunolocalization of vasopressin and neurophysin in neurosecretory cells of dehydrated rats

It has been proposed that neurosecretory material may be transported in a non-vesicular compartment in magnocellular neurons in the hypothalamus of osmotically stimulated rats. We have reexamined this issue using postembedding electron microscopic immunoperoxidase labeling of the secreted peptides (vasopressin and neurophysin) found in these neurons. Reaction product was found exclusively over neurosecretory vesicles in cell bodies, and in axons in the median eminence and neurohypophysis. The findings are consistent with an exclusive secretory vesicle location of the neuropeptides in the hypothalamo-neurohypophysial system of both normal and dehydrated rats.

Control of C-16 juvenile hormone biosynthesis in active corpora allata of female African locusts

Summary Corpora allata from 8-day-old female Locusta migratoria, during the phase of yolk deposition, exhibit high rates of C-16 juvenile hormone (JH) biosynthesis. The effect of different potential factors which may be involved in the regulation of corpora allata activity is reported. The biosynthetic activity of corpora allata was determined by radiochemical assay. In maturing females, no changes in corpora allata activity are detected during one daily cycle. Starvation reduces JH biosynthesis only 3 days after the beginning of the food deprivation. Suppression of the median neurosecretory material by electrocoagulation of the internal cardiaca tract (TCC-I) does not disturb JH biosynthesis whereas the transection of the allata I nerve fibres (NCA-I) or the electrocoagulation of the lateral neurosecretory pericarya results in a rapid decline of JH biosynthesis. These data indicate that the median and lateral allatotropins are different, and that only the lateral neurosecretory material exerts an allatos...

Development, endocrine organs and moulting in the embryos ofDysdercus cingulatus Fabr (Heteroptera: Pyrrhocoridae)

Embryonic development ofDysdercus cingulatus is briefly described. In the embryos, neurosecretory cells become evident in the median, lateral and ventral aspects of protocerebrum 84 hr after egg laying. The corpora cardiaca, the corpora allata and the prothoracic glands arise more or less simultaneously at 78 hr from the dorsolateral wall of the stomodaeum, from the mandibular segments and from the labial segments respectively. Secretory material appears in the brain neurosecretory cells and in the intrinsic cells of the corpus cardiacum at 84 hr and in the nervi corpori cardiaci and aorta at 90 hr. The cells of the prothoracic glands show signs of secretory activity at 90 hr, reaching maximum activity around 96 hr. The corpus allatum appears to be inactive in the embryo. Two embryonic moults appear between 96 hr and 110 hr. Consequence of events suggests that the neurosecretory material stimulates the prothoracic glands including embryonic moulting.

Elimination of the allatotropic activity in locusts by microsurgical and immunological methods: Evidence for humoral control of the corpora allata, hemolymph proteins, and ovary development

Transection of the nervous connections (NCC I) between the brain and the corpus cardiacum (group 1) and injection of anti-brain antibodies inhibited vitellogenin synthesis and ovary development in virgin Locusta migratoria females. Removal of the neurosecretory material by these methods changed the titer and the electrophoretic pattern of hemolymph proteins, including vitellogenin. Transection of NCC I at some distance from the brain resulted in bulbs with 30–200 μm diameter which were filled with stainable neurosecretory material (group 2). Oocyte maturation was delayed in group 2 but normal eggs were laid. The same happened if group 1 animals received daily injections of JH-III. It is concluded that a humoral factor is involved in the activation of JH-III biosynthesis. The factor is transported through the NCC I and is released into the hemolymph as allatotropin.

Electron diffraction of the metallic elements in the pineal organ of a freshwater fish, Mystus vittatus (Bloch.).

By electron diffraction pattern the presence of metallic elements, particularly chromium-nickel, chromium phosphide, copper, aluminum-copper and zinc has been shown in the pineal organ of a freshwater teleost, M. vittatus. It is likely that their occurrence within the pineal is due to binding with the neurosecretory material fractions/ligands.

Putative Neuroendrocrine Devices in the Nemertina—An Overview of Structure and Function

In the Nemertina there are three putative neuroendocrine devices: the cephalic gland, the cerebral organs and the neurosecretory system (cerebral ganglia). Cytological, behavioral and physiological evidence suggests involvement of these systems with preydetection, reproduction and volume regulation. The neuroendocrine function(s) of each of these devices must be considered putative except where classical ablation-replacement experiments have been performed. Thus, a specific role in gonad maturation has been successfully demonstrated for the cerebral ganglia, a primary neurosecretory center. Although the evidence is not as strong, cytological and physiological studies indicate that all three neuroendocrine devices, where they are present, are involved in response to variation in environmental osmolality. In the physiological response to osmotic variation, evidence most strongly points to neuroendocrine control (first order or second order) of extracellular volume. In this control, two different mechanisms may be involved, i.e. , stimulation of nephridial elimination of extracellular water and solutes and a change in permeability of the integument or gut to ions. In first order reactions, the neuroendocrine devices would act directly and independently upon a target organ such as the nephridia, integument, or gut to regulate extracellular volume. In a second order reaction, neurosecretory material would stimulate enhanced release of acid mucopolysaccharides from the cephalic gland or cerebral organs (depending on the species) into the vascular system. These substances (active principle or carrier) would, in turn, affect regulation of extracellular volume via the nephridia, integument, or gut. Further experimentation is required to separate the effects observed after neuroendocrine manipulation as well as the contributions made by each of the potential neuroendocrine devices.

Further studies of the secretory process in hypothalamo-neurohypophysial neurons: an analysis using immunocytochemistry, wheat germ agglutinin-peroxidase, and native peroxidase.

The axonal endoplasmic reticulum (ER) and synaptic-like (micro)vesicles within axon terminals of the neurohypophysis and their contribution to the secretory process in hypothalamo-neurohypophysial neurons have been investigated cytochemically in normal mice and in mice given 2% salt water to drink for stimulation of hormone synthesis in and release from these neurons. Cytochemical techniques included the peroxidase-antiperoxidase (PAP) immunocytochemical method for localization of neurophysin, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) as a tracer for the anterograde axonal transport of membrane from within the perikaryon, and blood-borne native horseradish peroxidase (HRP) as a tracer for internalized axon terminal membrane. The primary antiserum employed was directed against neurophysins I and II, the carrier proteins for the peptide hormones oxytocin and vasopressin, respectively. PAP reaction product was observed over neurosecretory granules but never over the endoplasmic reticulum, microvesicles or other organelles in axons and terminals of the neurohypophysis. WGA-HRP was delivered extracellularly to cell bodies of paraventricular neurons by cerebral ventriculocisternal perfusion. Internalized perikaryal surface membrane tagged with WGA-HRP was recycled through the innermost Golgi saccule (GERL) from which neurosecretory granules were formed. The anterograde axonal transport of membrane-bound WGA-HRP was manifested within the neurosecretory granules; WGA-HRP did not label the axonal reticulum or terminal microvesicles in the neurohypophysis. Blood-borne native HRP endocytosed into neurohypophysial terminals was associated with a plethora of microvesicles measuring 40-70 nm in diameter and vacuoles similar in size to the 100-300-nm-wide neurosecretory granules. The microvesicles contributed to the formation of numerous vacuoles. The internalization of axon terminal membrane as microvesicles incorporating HRP was quantitatively greater than vacuoles in both salt-stressed and control mice. The results suggest that in the hypothalamo-neurohypophysial system of the mouse the axonal ER and terminal microvesicles are not involved in the transport, storage, and exocytosis of neurosecretory material and perhaps other molecules processed through the innermost Golgi saccule. Nevertheless, a prominent population of the microvesicles within axon terminals of the neurohypophysis does participate in the secretory process. These vesicles are involved directly in the internalization of the terminal surface membrane subsequent to release of secretory granule content.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of tranverse cuts caudal to the preoptic recess on the hypothalamo-neurohypophyseal neurosecretomy system

Electrolytic lesions of tissue surrounding the preoptic recess (AV3V region) appear to cause loss of stimulatory input to the supraoptic nuclei from angiotensin receptors and osmoreceptors. To investigate the pathways affected by AV3V lesions, we observed the ultrastructural effects of coronal cuts in a plane caudal to the organum vasculosum lamina terminalis upon supraoptic nuclei and neural lobes of rats. Like AV3V lesions, these cuts caused degeneration of axons and terminals in the supraoptic nuclei. Degenerating terminals lay in axodendritic synapses and in axosomatic synapses on neurosecretory cells. Unlike AV3V lesions, the cuts did not result in an appearance of decreased secretory activity in the supraoptic nuclei or decreased release of hormone from the neural lobe. On the contrary, terminals in the neural lobe tended to be depleted of neurosecretory material, and glial cell processes tended to be withdrawn from the secretory interface at the basal lamina surrounding fenestrated capillaries; both are changes which have been associated with enhanced hormone release. We suggest that inhibitory input to the supraoptic nuclei is lost as a result of these cuts.

Ultrastructural changes and proliferation of pituicytes in mouse posterior lobe during water deprivation and rehydration.

Ultrastructural changes and proliferation of pituicytes during water deprivation and rehydration were studied in the posterior lobe of C57BL/Tw mice. Deprivation for 3 days brought about a significant increase in the number of electron-dense bodies (lysosomes) in pituicyte perikarya and their processes. The frequency of pituicytes enclosing neurosecretory axons in their cytoplasm significantly decreased as compared with that of the controls. 12-hour rehydration following deprivation for 3 days induced extensive development of rough endoplasmic reticulum and Golgi apparatus and an increase in frequency of neurosecretory axons enwrapped by pituicyte cytoplasm. However, at 2 days of rehydration the morphology of pituicytes was no more different from that of the controls. Mitotic figures of pituicytes were not encountered throughout the deprivation period of 6 days, but rehydration for 12 h and 1, 2, or 3 days following deprivation for 3 or 6 days was effective in eliciting an increase in mitotic activity. The present results indicate that pituicytes in the mouse posterior lobe are intimately related with the secretory mechanism of neurosecretory material from the neurosecretory axons and that the proliferation of pituicytes is stimulated in conditions of reaccumulation of neurosecretory material.

Régulations aminergique et cholinergique du système caudal neurosécréteur de l'omble de fontaine, Salvelinus fontinalis, en relation avec l'osmo-iono-regulation

The innervation of the caudal neurosecretory system of the brook trout, Salvelinus fontinalis, was studied under light and electron microscopy in order to characterize its nature, distribution, and regulatory function over the activity of the caudal neurosecretory cells. A dual innervation of the cell bodies and axons of neurosecretory cells was disclosed. One type of axosomatic connection exhibited small lucent vesicles and large dense-cored granules. These boutons were identified as monoaminergic since they appeared depleted after reserpine treatment and they were selectively labeled with 5-OH-dopamine. In fish exposed to demineralized water, reserpine induced a condition that stimulated the synthetic activity of caudal neurosecretory cells, a clear reduction of this activity, according to morphometric (cell and nucleus diameters) and ultrastructural criteria (dimensions of the Golgi complex). By comparison, no significant variation of the synthetic activity was noted in freshwater-adapted trout treated with reserpine. A second type of innervation was also identified as cholinergic by histochemical localization of acetylcholinesterase. Electron microscopic analysis also revealed axosomatic and axoaxonic cholinergic synaptic connections with characteristic small 500-Å diameter lucent vesicles. The injection of fenitrothion, an anticholinesterase agent, enhanced discharge of neurosecretory material from axonal endings of caudal cells while the synthetic activity did not appear to be modified. Our findings suggest an important role of aminergic and cholinergic controls over the response of the caudal neurosecretory system of Salvelinus fontinalis during hyperosmotic adaptation.