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At least 739 records · Page 41Linked to original sources
PubMed2005

Phosphatidylinositol 3-kinase C2alpha is essential for ATP-dependent priming of neurosecretory granule exocytosis.

Neurotransmitter release and hormonal secretion are highly regulated processes culminating in the calcium-dependent fusion of secretory vesicles with the plasma membrane. Here, we have identified a role for phosphatidylinositol 3-kinase C2alpha (PI3K-C2alpha) and its main catalytic product, PtdIns3P, in regulated exocytosis. In neuroendocrine cells, PI3K-C2alpha is present on a subpopulation of mature secretory granules. Impairment of PI3K-C2alpha function specifically inhibits the ATP-dependent priming phase of exocytosis. Overexpression of wild-type PI3K-C2alpha enhanced secretion, whereas transfection of PC12 cells with a catalytically inactive PI3K-C2alpha mutant or a 2xFYVE domain sequestering PtdIns3P abolished secretion. Based on these results, we propose that production of PtdIns3P by PI3K-C2alpha is required for acquisition of fusion competence in neurosecretion.

Adenosine Triphosphate↗
PubMed1982

Neuroendocrine pacemaker for growth, development and ageing.

The hypothesis is formulated that ageing is mediated through alteration in a pacemaker system located in the hypothalamus and dependent on serotonin-thyroid hormone interactions. Data in support of this hypothesis include: imbalance in central nervous system (CNS) neurotransmitters with ageing, with serotonin dominance; impairment of hypothalamic neurosecretion; increased heterogeneity of thyrotropin forms secreted from the aged pituitary; and drug and dietary manipulation of CNS serotonin with consequent effects on endocrine function and homeostasis.

Aging↗
PubMed2006

A role for the transcriptional repressor REST in maintaining the phenotype of neurosecretory-deficient PC12 cells.

The rat PC12 variant cell line, A35C, lacks regulated secretory organelles due to a selective transcriptional block. Hence, A35C may provide clues about the mechanisms that underlie control of neurosecretion. We used mRNA microarray profiling to examine gene expression in A35C. Genes for regulated secretory proteins were down-regulated, while other membrane trafficking pathways were unaffected. A subset of genes repressed in A35C contain binding sites for the neuronal transcriptional repressor, RE1-silencing transcription factor (REST), and REST is expressed in A35C but not normal PC12 cells. Blocking the activity of REST in A35C using a dominant-negative construct induced the reappearance of mRNAs for synaptophysin, chromogranin A, synaptotagmin IV and the beta3 subunit of the voltage-gated sodium channel (Scn3b), all of which contain RE1 sites in their genes. In the case of Scn3b, the corresponding protein was also re-expressed. Granule and synaptic vesicle proteins were not re-expressed at the protein level, despite reactivation of their mRNA, suggesting the existence of additional post-transcriptional control for these proteins. Our work identifies one of the mechanisms underlying the phenotype of neurosecretory-deficient neuroendocrine cells, and begins to define the critical components that determine a key aspect of the neuroendocrine phenotype.

Animals↗
PubMed1975

Antipsychotic drugs: direct correlation between clinical potency and presynaptic action on dopamine neurons.

Neuroleptic (antipsychotic) drugs inhibited the electrically stimulated release of [3-H] dopamine from rat striatal slices. The concentrations for 50 percent inhibition (ranging from 11.5 nanomolar for spiroperidol to 800 nanomolar for thioridazine) correlated closely with the average daily dosages of 25 neuroleptic drugs used clinically for schizophrenia. The correlation includes butyrophenones, phenothiazines, reserpine, pimozide, clozapine, and (plus)- butaclamol. Clinically inactive isomers [trans-thiothixene, trans-flupenthixol, and (minus)-butaclamol] required 20 to 1000 times higher concentrations than the active isomers to inhibit release. Compared to the inhibition of [3-H] dopamine release, much higher neuroleptic concentrations were needed to inhibit the electrically stimulated release of other neurotransmitters--[3-H] acetylcholine, [3-H-a1 (gamma-aminobutyric acid). The neuroleptic drugs may block the presynaptic coupling between impulse and neurosecretion.

Acetylcholine↗
PubMed1978

Pars nervosa hypophyseos in chronic audiovibratory stress.

In the nervous part of the hypophysis, significant decrease in the quantity of neurosecretion, hypertrophy, and frequent findings of mitosis of adenopituicytes occur under the influence of noise and vibrations. In chronic audiovibratory stress, the phenomenon of hyperplasia of adenopituicytes and intracytoplasmic presence of structural elements of neurosecretory fibres in disintegration are noticeable. Heterogeneity of neurosecretory fibres is characteristically manifested in the presence of dilated Herring bodies with preserved structure, occurrence of nerve swellings very variable in structure, with numerous polymorphous inclusions and autolytic bodies, or with large vacuoles, few secretory granules and few mitochondria. There are some endings of neurosecretory fibres with many clear microvesicles and few granules, as well as the endings abounding only in clear microvesicles, particularly in pericapillary spaces. The results obtained point to strong stress-inducing effects of noise and vibrations upon the nervous part of the hypophysis.

Animals↗
PubMedDate not supplied

[Pathogenesis of lithium polyuria].

An attempt is made to elucidate the pathogenesis of polyuria arising consequent upon medication of affective states with lithium salts. Experiments conducted with 54 male-rats showed that changes in the neurosecretion of supraoptic nuclei of the hypothalamus and neurohypophysis that take place after a course-wise intraperitoneal administration in amounts of 200 mg/kg (2/9DL20) of lithium chloride per 24 hours for a duration of 6 days occur parallel with histochemical changes of renal acid muconpolysaccharides and they accord with the nature of diuresis disorders. By the 5th day of the experiment the compound perverts the antidiuretic effect of a single subcutaneous injection of pituitrin (10 U/kg). The authors infer therefrom that polyuria emerging after introduction of lithium salts is caused by a deranged synthesis and secretion of the diuretic hormone and also by the ability of lithium to mitigate the action of this hormone on the kidneys.

Animals↗
PubMed2004

Effect of Dimethoate (Rogor 30% EC) on the brain neurosecretory cells of third instar grubs of Oryctes rhinoceros L. (Coleoptera : Scarabaeidae).

The brain neurosecretory cells of III instar grubs of Oryctes rhinoceros were exposed to insecticide Dimethoate (Rogor 30% EC) in the laboratory condition. The sublethal doses (0.125, 0.25 and 0.5%) of Rogor at time intervals of 8, 16 and 24 h have produced marked changes in the structure and the secretory activities of medial and lateral neurosecretory cells. Rogor stimulates the synthetic activity of these cells at the initial stages of its action and results in the accumulation of neurosecretory materials (NSM) in the cytoplasm. The decreased neurosecretion at later stages of the action was due to its transportation through the axons before the death of treated grubs. Similarly, vacuolization, shrinking and degeneration of cells were also observed in treated grubs.

Analysis of Variance↗
PubMed1988

[The hypothalamic-hypophyseal neurosecretory system of the Alosa fallax nilotica. A histological and ultrastructural study].

We studied the morphological, histochemical and ultrastructural aspects of the hypothalamic-pituitary system in the Alosa fallax nilotica. The secretory activity of the preoptic nucleus and of the lateral tuberal nucleus was also investigated with regard to the gonadal growth and development during the reproductive sexual cycle and the changing migrational environmental conditions (anadromous and catadromous phases). The hypothalamic-pituitary system is formed by: centers of neurosecretion synthesis (parvo and magnocellular preoptic nucleus and lateral tuberal nucleus), a conduit system (preoptic infundibular-neurohypophyseal tract) and a collecting center (neurohypophysis intermediate lobe). The neurosecretory cells show two distinct types of secretory granules with different ultrastructural features probably representing the morphological expression of two distinct hormones. These cells show also characterizations of cytoplasmic areas related to peculiar cyclic functional stages concerned with the reproductive sexual cycle. We observed significant quantitative and qualitative changes of the neurons both in the parvo- and magnocellular preoptic nucleus and in the lateral tuberal nucleus during anadromous migration and during spawning and fertilization. Almost insignificant changes of the neurosecretory material were observed in the preoptic-pituitary tract and in the intermediate-neurohypophyseal lobe. The results show that the hypothalamic-pituitary neurosecretory system play an important role in the osmoregulation (magnocellular preoptic nucleus) and on the reproductive cycle (lateral tuberal nucleus). The system probably also controls some other metabolic activities (utilization of the stored material) linked to peculiar environmental and feeding conditions.

Animals↗
PubMed1985

[Neurosecretory synapses, yesterday and today].

The concept of peptidergic neurotransmission in the central nervous system ranks high in contemporary neurobiology. It was first formulated by J. Barry when reporting, in 1954-55, his observation with light microscopy of the existence of "Gomori-positive" synapses in sections of the mammalian brain. However, this important discovery had virtually no impact on the scientific community for about twenty years because of an extremely restrictive definition of "neurosecretion" during this period by the practitioners of the new field known as neuroendocrinology. The rejection of Barry's finding raises numerous epistemological questions; it provides another example of a "premature discovery", such as those of A.A. Berthold (testicular transplant studies) and of J.G. Mendel (artificial plant hybridization) during the last century.

Animals↗
PubMed1977

[Coated vesicles and their functional role in animal cells].

A review is made of the structural organization of coated vesicles, their contents, mode of formation and of destruction and intracellular routes in different cells of various species. Special attention is given to the participation of coated vesicles in the segregation and transferring of diverse substances in the cytoplasm, as well as to the final biological effects of these substances on cell metabolizm. The participation of coated vesicles in intracellular digestion, secretion and neurosecretion, in vitellogenesis and some other cellular function is considered in details.

Animals↗
PubMed1978

[Changes in the hypothalamo-hyophyseal neurosceretory system of mammals following pituitary stalk transection and hypophysectomy].

Hypophysectomy and pituitary stalk section result in dramatic morpho-functional changes in all parts of mammalian hypothalamo-hypophyseal neurosecretory system. Reorganization of the hypophyseal stalk consists of several interconnected but differing in time processes. Simultaneously with the developing traumatic changes (degeneration of the sectioned neurosecretory fibers, secretory disorders) proliferation of pituicytes with characteristic phagocytic activity is observed. A little bit later, intensive mitotic division of endothelial cells and capillary formation piercing the stalk periphery begins. At the same time, a new way for blood outflow from the capillaries of the primary portal plexus into the synuses of the brain pias is restored. Degenerated neurosecretory fibers are gradually substituted by regenerating fibers forming a dense network in heavily vascularizated stalk parts. As differentiation of endothelial cells and regeneration of neurosecretory fibers procede, axovasal contacts are gradually forming. At that time the hypophyseal stalk begins functioning as a neurohumoral organ but morpho-functionally less perfect than the posterior hypophyseal lobule. In the median eminence of the operated animals, unlike the intact ones, neurosecrete is accumulating around the capillaries of the portal plexus. Mechanical damage of neurosecretory fibers during the operation results in degeneration of a greater number of neurosecretory cells in the supraoptical and paraventricular nuclei. Preserved cells have an increased functional activity because of neurohormonal deficiency in the organism. As a result of the structural changes mentioned, diabetes mellitus develops, subsiding gradually with time course.

Adaptation, Physiological↗
PubMed1974

[The influence of a protein deficient diet on the activity of the hypothalamus-neurohypophysial system].

In mature as well as in prebuberal rats protein deficient diets activate the hypothalamo-neurohypophysial system, which is morphologically characterised by the decrease of neurosecret in the posterior pituitary and the increase of the cell nuclear volume of the supraoptic and paraventricular nuclei. The neuronal activity is stimulated significantly stronger by a protein deficient diet with addition of some essential amino acids (lysine, tryptophane, threonine and isoleucine) than by an extremely deficient protein diet in so far as it occurs in the cell nuclear volume of both neurosecretoric hypothalamic nuclei.

Age Factors↗
PubMed1980

[Histochemical changes in the neurosecretory hypothalamic nuclei as result of an intoxication with mercury compounds (author's transl)].

The effect of experimental poisoning by organic compounds, frequently used in agriculture as fungicides, on the histochemical and histoenzymic pattern of the hypothalamic neurosecretory system has been studied. The experimental rats were fed by means of a gastric tube with the following compounds: Phenylmercuryacetate, 0.1 g daily, for 10 days; Aethylmercury-p-toluenesulphanilide, 0.2 g daily, for 10 days, and Methoxyethylmercurychloride (Ceresan), 0.1 g daily, for 6 days. The histochemical and histoenzymic investigations have shown that ingestion of Phenylmercuryacetate brought about an increase in the release of antidiuretic hormone (ADH) with a concomitant enhancement of production of neurosecretory substances. The peroral administration of Aethylmercury-p-toluenesulphanilide and of Methoxyethylmercury chloride instead, resulted in the accumulation of the neurosecretion within the hypothalamic-hypophyseal system with a parallel inhibition of ADH release. The experimental poisoning of Ceresan had also a stimulatory effect on the activity of many enzymes in the neurosecretory nuclei of the rat hypothalamus. Morphological changes resulting from the experimental intoxication were only rarely observed in the neurosecretory cells of the investigated hypothalamic nuclei.

Animals↗
PubMed1982

[The hypothalamo-hypophyseo-ovarian systems in rats after deafferentiation of the mediobasal hypothalamus].

Complete surgical deafferentation of the medio-basal hypothalamus (MBH) in rats entails suppression of the oestrus cycle as well as a decrease of luteinizing hormone, estrogens and progesterone release into the blood due to a sharp fall of the luliberine content in the median eminence and arquate nuclei. No connection was revealed between the character of oestrus disturbances and the extent of damage or isolation of the arquate, ventromedial, supraoptic and paraventricular nuclei and the amount of Homori-positive neurosecreted in the MBH. In development of permanent diestrus the MBH isolation was more complete than in the preservation of irregular cycle. The luliberine seems to be produced mainly in the anterior hypothalamus of rats whereas the MBH alone fails to maintain even its tonic secretion. Even in complete surgical isolation of the MBH, separate fibers of the luliberinergic cells penetrate into the MBH maintaining there a certain amount of luliberin and preserving synthesis of the luteinizing hormone in the hypophysis with its decreased release into the blood.

5-Hydroxytryptophan↗
PubMed1983

[Structural characteristics of the hypothalamo-hypophyseal neurosecretory system in the field mouse (Arvicola terrestris)].

The structure of the hypothalamo-hypophysial neurosecretory system (HHNS) has been studied light optically in the Arvicola terrestris that possesses a specific reduction of the concentrating renal function. There are neurosecretory cells (NSC) with cytoplasmic vacuoles in the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei that secrete antidiuretic hormone. These cells are situated mainly in the caudal part of the nucleus and, evidently, perform an osmoreceptory function. For the hypothalamic nuclei studied, characteristic are single cells with polyploid nuclei, their appearance is supposed to be connected with a necessity to intensity the processes of the neurohormonal synthesis. In the NSC, PVN and partly in the SON axons, as well as in the hypothalamo-hypophysial tract fibers and their terminals there is, together with the granular neurosecrete, the one having the form of large homogeneous colloid drops, which are, appearantly, some quickly restorted neurohormonal reserve when certain unfavourable conditions appear. These morphological peculiarities of the HHNS appear to be certain signs of an adaptive mechanism of the osmoregulatory system are species-specific, since the ecological specialization of the animals studied is connected with hyperhydratation conditions.

Animals↗
PubMed1993

Changes of neurosecretory material content in neurohypophysis of rats submitted to chronic treatment with copper.

The effect of copper on neurosecretory material (NSM) content in neurohypophysis of rats was investigated. The control group of animal was treated with deionized water, the others with copper sulphate solutions containing 3.6 or 12 mg Cu/dm3 for 7 or 14 days. Sections of neurohypophysis were stained by the method reflecting the neurosecretion content in this organ. It was found that copper induces an accumulation of NSM in neurohypophysis. Such an effect depends on the concentration of copper in solutions and on time of treatment.

Animals↗
PubMed1977

[Changes in the functional activity of the hypothalamo-hypophyseal neurosecretory system in acute experimental pancreatitis].

Changes in the hypothalamo-hypophyseal neurosecretory system were studied in 29 dogs 6 h and 1, 7, 30 days after development of acute experimental pancreatitis against the background of treatment with single paranephral novocaine blockade and without treatment. Pancreatitis was caused by K. D. Toskin's method. The disease was accompanied by a sharp increase of the neurosecretory system activity which found its manifestation in hypersecretion of the neurosecretory nuclei cells increased moderately, a considerable quantity of neurosecretion was preserved in neurohypophysis, i.e. there were no signs of overstrain of the neurosecretory system.

Acute Disease↗
PubMedDate not supplied

Inhibitory effect of dopamine on acetylcholine release from caudate nucleus.

It has been shown that dopamine inhibits the release of acetylcholine (ACh) from nerve terminals of caudate cholinergic interneurons, and the imbalance between dopaminergic and cholinergic system by 6-hydroxydopamine pretreatment leads to an increased ACh release. The Parkinson-syndrome induced by drugs which depress dopaminergic function either by reducing the output of dopamine, such as reserpine, or by antagonizing its action on DA receptors, as for instance haloperidol or chlorpromazine, can be attributed to the augmented release of ACh from caudate cholinergic nerve terminals and a consequent increase of cholinergic outflow from caudate nucleus. However, athetoid and choreiform hyperkinesis in patients and hypermotility in animals might result from increased dopaminergic outflow of nigro-striatal pathway and a consequent reduction in cholinergic neurosecretion of caudate nucleus.

Acetylcholine↗