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At least 19 recordsLinked to original sources
PubMed1992

Monoclonal antibodies against Nereis virens brain homogenates as probes for isolation and in situ detection of new neurosecretions.

The brain of Nereis contains 26 ganglionic nuclei which produce numerous neurosecretions. Only a few of them have been characterized. The production of monoclonal antibodies was adopted as an approach to discover unknown neurosecretions. Monoclonal antibodies produced against Nereis virens brain homogenates were selected using stepwise ELISA tests first with brain homogenates, then with brain neurosecretions. Eight antibodies specific for Nereis neurosecretions were selected. The results are illustrated with one of these monoclonal antibodies which was directed against a major peak after HPLC purification of brain neurosecretions. This antibody was subsequently used for the in situ detection of recognized epitope(s) in the brain and ventral nerve cord cells.

Animals↗
PubMed1992

Ca(2+)-independent and Ca(2+)-dependent stimulation of quantal neurosecretion in avian ciliary ganglion neurons.

1. Although it is generally agreed that Ca2+ couples depolarization to the release of neurotransmitters, hypertonic saline and ethanol (ETOH) evoke neurosecretion independent of extracellular Ca2+. One possible explanation is that these agents release Ca2+ from an intracellular store that then stimulates Ca(2+)-dependent neurosecretion. An alternative explanation is that these agents act independently of Ca2+. 2. This work extends previous observations on the action of ETOH and hypertonic solutions (HOSM) on neurons to include effects on [Ca2+]i. We have looked for Ca(2+)-independent or -dependent neurosecretion evoked by these agents in parasympathetic postganglionic neurons dissociated from chick ciliary ganglia and maintained in tissue culture. The change in concentration of free Ca2+ in the micromolar range inside neurons ([Ca2+]i) was measured with indo-1 with the use of a Meridian ACAS 470 laser scanning microspectrophotometer. 3. Elevated concentration of extracellular KCl increased [Ca2+]i and the frequency of quantal events. Also, a twofold increase in osmotic pressure (HOSM) produced a similar increase in quantal release and a significant rise in [Ca2+]i; however, the Ca2+ appeared to come from intracellular stores. 4. In contrast, ETOH stimulated quantal neurosecretion without a measurable change in [Ca2+]i. It appears the alcohol exerts its influence on some stage in the process of exocytosis that is distal to or independent of the site of Ca2+ action. 5. The effects of high [KCl]o and osmotic pressure were occlusive. This is explained in part by the observation that hypertonicity reduced Ca2+ current, but an action on Ca2+ stores is also likely.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

[Experimental hepatic encephalopathy. The effect of portocaval shunt on the evolution of the anterior hypothalamic neurosecretion in the rat (author's transl)].

The evolution of the anterior hypothalamic neurosecretion is studied in control, sham-operated and portocaval shunt rats. In sham-operated related to control rats, no modification of the anterior hypothalamic neurosecretion is observed. In portocaval shunt rats, the hypothalamic neurosecretion increases. This increase is mainly observed into the median eminence in all the portocaval shunt rats. The hypothesis according to which the modification of neurosecretory acitivity of the hypothalamic structures may be related to a discrepancy between the central monoamines is discussed.

Animals↗
PubMed1978

Histopathology and histochemistry of the insects treated with chemosterilants VI: brain damage including reduced neurosecretion caused by chemosterilants in Periplaneta americana (L).

The brain is damaged and neurosecretion is reduced in the P. americana treated with chemosterilants thio-tepa and bis (dimethylamino) dithiazolium chloride. The damage includes, separation of neurolemma, vacuolisation and chromatolysis in the nuclei of neurons and extensive damage to fibres. Reduced neurosecretion, vacuolisation in the cytoplasm and karyolysis in the nucleus of neurosecretory cells, are also observed. These changes in the brain are of considerable importance to understand the mode of action of the chemosterilants.

Animals↗
PubMed1975

[Distribution of neurosecretion in the neurohypophysis of the cow during and following milking].

Studies by optical microscopy showed that discharge of neurosecretion brought about by the stimulus of milking took place in the zona centralis and also in the transitional and main sectors of the zona terminalis. The zona marginalis, zona metacentralis and the peripheral sector of the zona terminalis were not involved. In pituitary glands fixed at various time intervals after milking, the increase in secretion content and the disappearance of perivascular accumulations of secretion were evidently a result of renewed production and storage of neurosecretion in the hypophysis. The renewed homogeneous distribution of secretion in the zona terminalis had not been completed one hour after milking. The increase in size and number of pituicytes and their frequent appearance in adventitious tissue of vessels and around sinusoid capillaries after the liberation of secretion may be related to degradation processes of neurosecretory material.

Animals↗
PubMed1988

Peripubertal development of noradrenergic stimulation of luteinizing hormone-releasing hormone neurosecretion in vitro.

The effect of age on norepinephrine (NE) stimulation of luteinizing hormone-releasing hormone (LH-RH) secretion from preoptic area-mediobasal hypothalamic (POA-MBH) explants was examined in the present study. Explants were obtained from juvenile (9-day-old), prepubertal (29-day-old) and adult female rats. Following decapitation and surgical isolation, POA-MBH explants were individually perifused with culture medium which was collected for radioimmunoassay of LH-RH. Explants were exposed to two pulses of medium containing NE (5 x 10(-4) M, peak concentration) and a terminal pulse of medium containing KCl (45 mM, peak concentration) for assessment of viability. POA-MBH explants obtained from prepubertal female rats exhibited increased LH-RH release in response to the two pulses of NE and subsequent KCl pulse (P less than 0.05). NE was without effect in stimulating LH-RH neurosecretion from POA-MBH explants obtained from 9-day-old female rats although these explants were responsive to KCl (P less than 0.01). Two-day pretreatment of 9-day-old, and prepubertal rats with estradiol benzoate (EB) did not alter the LH-RH response to this dose of NE or KCl (no group or interaction effects) in prepubertal female rat explants and did not render the explants from 9-day-old rats responsive to NE. Furthermore, NE was equally effective in stimulating LH-RH release from explants obtained from estradiol-treated or control ovariectomized adult rats. These observations demonstrate a peripubertal activation of the stimulatory effect of NE on LH-RH release from POA-MBH explants in vitro. Although these data also suggest that estrogen is not obligatory for NE stimulation of LH-RH release from POA-MBH explants, further investigation is required to determine the developmental time course and estrogen dependency of the noradrenergic stimulation of LH-RH neurosecretion and to evaluate whether estrogen alters the sensitivity of POA-MBH explants to lower concentrations of NE as has been previously reported for median eminence fragments.

Animals↗
PubMed1986

Hormones, neurosecretions, and growth factors as signal molecules for intercellular communication.

Chemical signals, whether in the form of hormones, neurosecretions (neurotransmitters and neuropeptides), or growth factors and chalones are used to communicate information to cells at all stages of their life cycle. These signals inform the cells when it is time to progress through developmental change, when to change the rates of various activities (e.g. metabolism or contraction), and, in some cases, even when it is time to die. Throughout all of these interactive exchanges, the signal molecule itself carries no intrinsic message of a universal nature. The chemical identity of the signal molecule has meaning only for those cells competent to receive the signal (i.e. does it possess an appropriate receptor?). Moreover, it is the nature of the cell receiving the signal (itself the product of innumerable previous encounters with signals from other cells) that dictates the specific response that a particular signal will evoke. The signal emitted by the communicating cell only informs the target cell that it is time to act in a manner consistent with that signal. The majority of the discussion has been from the perspective of vertebrate organisms. Moreover, of necessity, the discussion has been general and superficial. The primary objective of the preceding discussion has been to underscore major similarities and differences existing among hormones, neurosecretions (neurotransmitters and neuropeptides), and growth factors as information-bearing substances used in communication among vertebrate cells. It should be realized that similar means of communication are employed by multicellular invertebrates, by plants, and even by single-celled organisms such as the protists and bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Communication↗
PubMed1977

The effect of age and strain on the amount of neurosecretion.

The work carried on 4 groups of guinea pigs, each group consisting of five animals showed, that the age and strain may influence the amount of neurosecretion, with the older (except 6 month old animals which passed maturing stage) secreting more than that of younger. And the amount of neurosecretion in animals of the black strain is somehow lower than the ones of the grey.

Age Factors↗
PubMed1992

An electron microscopic study of neurosecretion in the cerebral ganglion of the earthworm.

Non-synaptic, exocytotic release of neurosecretory granules in cerebral ganglion neurons was observed electron microscopically in 3 species of the oligochaete annelids Aporrectodea caliginosa, Octolasion cyaneum and Lumbricus terrestris. In addition to the features indicating exocytotic release of neurosecretory granules into perineuronal space, possible features of neurosecretion into blood vessels were seen within the cerebral ganglion. Axon terminals in synaptic contact with perikaryal profiles of cerebral ganglion neurons were also found.

Animals↗
PubMed1988

The neuroendocrine paraventricular hypothalamus: receptors, signal transduction, mRNA and neurosecretion.

The hypothalamus is one of the most studied areas of the central nervous system. Many of its functions are understood and there is an extensive literature on its role in the control of pituitary hormone secretion, autonomic nervous system activity, regulation of salt, water and food ingestion, body temperature regulation and aspects of behaviour. Although the role of the hypothalamus in the control of pituitary secretion was postulated in the early 1900s, the chemical nature of these control mechanisms has only been documented in the last few years. The opioid peptides represent one particular family of chemical compounds which have been shown to have many effects on pituitary hormone secretion. Exogenous opioids inhibit the neurosecretion of both vasopressin and oxytocin from the posterior pituitary neurosecretory terminals of hypothalamic cell bodies. Opioids also have major actions on the secretory activity of the anterior pituitary which has no innervation from the hypothalamus, but which is regulated by blood-borne factors in the hypophyseal portal circulation which runs from the median eminence of the hypothalamus. It was therefore of considerable interest when it was discovered that endogenous opioid peptides could be detected both in the neurohypophyseal system and in cells which project into the median eminence. The simple presence of a peptide in a neurone does not necessarily imply a function. If, however, we can demonstrate that regulation of the synthesis of the peptide occurs in a manner which corresponds with the expected role of the agent, this provides powerful data in support of a genuine physiological function. The elucidation of the genomic structure of the precursors for the three endogenous opioid peptides has provided us with the ability to measure mRNA for these peptides in defined areas of the brain and to assess their response to appropriate stimuli. Not only does mRNA for the endogenous opioid dynorphin coexist in the same cells as vasopressin but we have now been able to demonstrate that stimuli to vasopressin secretion also result in a markedly increased accumulation of dynorphin mRNA. Similarly, previous studies have shown that opioid peptides derived from another precursor--pro-enkephalin A--coexist with corticotrophin releasing factor in a different group of hypothalamic cells. We have now been able to demonstrate that stresses which result in an accumulation of corticotrophin releasing factor mRNA also result in increased pro-enkephalin mRNA in the same area. This considerably strengthens the hypothesis that endogenous opioids do play a significant role in the control of hypophyseal secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Potentiation of sympathetic neurosecretion by forskolin and cyclic AMP in the rabbit iris-ciliary body.

Forskolin has been reported to stimulate cAMP formation and reduce intraocular pressure in rabbit and primate eyes. In view of recent evidence for the involvement of cAMP in modulation of transmitter release at adrenergic synapses, we have investigated the presynaptic effects of forskolin and other cAMP activators on field-stimulated secretion of 3H-norepinephrine (3H-NE) in the isolated, perfused rabbit iris-ciliary body. Forskolin (10(-7)-10(-5) M) was found to markedly enhance stimulation-evoked 3H-NE release without affecting basal (spontaneous) release. The response to forskolin was potentiated by the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX; 0.5 mM) and was mimicked by the cell-permeant cyclic nucleotide analog 8-bromo-cAMP. 8-bromo-cGMP also produce a small enhancement of stimulus-evoked 3H-NE secretion, whereas IBMX alone had little effect on either stimulated or basal secretion. These results suggest that cAMP may play an important neuromodulatory role in regulation of norepinephrine release at intraocular synapses, and raise the possibility that the ocular hypotensive response to forskolin in rabbit eyes may be mediated, in part, by enhanced adrenergic neurosecretion.

Animals↗
PubMed1975

[Distribution of neurosecretion in the supraoptic and paraventricular nuclei of the cow before and following milking].

Distribution of neurosecretion and enzymes in the nuclei was studied by optical microscopy and histochemical methods. The stimulus of milking had no effect on the amount of secretion in the supraoptic nucleus, but synthesis of secretion in the paraventricular nucleus was stimulated by oxytocin liberation associated with milking, and it was still present 60 minutes after milking. It seems that each nuclear region is a functionally independent unit.

Animals↗
PubMed1985

The influence of the antimitotic drug CCNU on the neurosecretion of rat hypothalamo-hypophyseal system.

The purpose of this investigation was to evaluate the influence of the antimitotic drug CCNU on the morphology of the hypothalamo-hypophyseal neurosecretory system of rat. Adult Wistar rats were treated intragastrically with 2.5 mg CCNU once a week during 3 consecutive weeks and 5 mg at the end of the 4th week. The brains and hypophyses were fixed in Zenker-formol solution. Paraffin slices were stained with chromhematoxylin to demonstrate neurosecretory material and with cresyl violet. PAS reaction was also performed. The experiment resulted in disturbances of the neurosecretory function of the hypothalamo-hypophyseal system in form of alteration in the content of neurosecretion in the neuronal cytoplasm and processes within supraoptic and paraventricular nuclei as well as in the neurohypophysis. The morphometric measurements showed enlargement of the cell nuclei and cytoplasm volumes in the nucleus supraopticus of hypothalamus.

Animals↗