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Pinealocyte

About: Pinealocyte is a research topic. Over the lifetime, 1605 publications have been published within this topic receiving 55609 citations.


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Journal ArticleDOI
TL;DR: The results of this study suggest that the rate of pineal melatonin synthesis is dependent on the free cytoplasmic pool of 5-HT in pinealocytes and that the drug-induced elevation of this pool stimulates melatonin formation and increases circulating melatonin levels.

30 citations

Journal ArticleDOI
TL;DR: The presence of synaptophysin in pinealocytes of the normal pineal, including the deep portions of the gland, emphasizes the paraneuronal character of these cells.
Abstract: Synaptophysin (protein p38), a major integral membrane glycoprotein of small presynaptic vesicles, was localized immunohistochemically in semithin sections of the superficial pineal gland of the Mongolian gerbil (Meriones unguiculatus). Synaptophysin immunoreactivity could be detected in all pinealocytes, which were visualized with antibodies directed against neuron-specific enolase (NSE) in adjacent sections. No p38 immunoreactivity was discernible in the interstitial glial cells, which showed a heterogeneous pattern of immunostaining for the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. Pinealocytes exhibited considerable intercellular differences in the densities of immunostaining. The various degrees of synaptophysin immunoreactivities in pinealocytes were not correlated with the densities of NSE immunostaining. Nerve terminals and varicosities displayed stronger immunoreactivities than pinealocytes. They were particularly numerous in the perivascular spaces. It is not clear whether this distribution indicates an innervation of pineal capillaries in addition to the functionally important innervation of pinealocytes. Several highly p38-positive dots of variable size were a conspicuous feature throughout the gland. By the consecutive semithin-thin section technique, they could be identified as processes of pinealocytes, filled with accumulations of small clear vesicles. Obviously, these vesicles represent the major site of synaptophysin immunoreactivity in pinealocytes. In the gerbil, similar vesicles have been ascribed a role in the secretory activity of the gland, and/or in the transport of calcium. The intercellular differences in the degrees of p38 immunostaining may, therefore, reflect different states of a specific cellular activity. The presence of synaptophysin in pinealocytes of the normal pineal, including the deep portions of the gland, emphasizes the paraneuronal character of these cells.

30 citations

Book ChapterDOI
01 Jan 1974
TL;DR: The pineal participates, through the secretion of melatonin, in the control of certain neuroendocrine and neurophysiological rhythms; it also mediates some of the effects of light on gonadal maturation, the ovulatory cycle, and the secrete of pituitary hormones.
Abstract: Publisher Summary The indoleamine serotonin is found in several tissues in the body; its 5-methoxy derivatives are primarily produced by and have been isolated from the pineal. Melatonin (5-methoxy-N-acetyltryptamine) is the prototype of this family of biologically active compounds; its characterization constituted a landmark in the study of pineal physiology inasmuch as it was the first substance to be characterized in the pineal that reproduced many of the effects of pineal extracts or reversed the endocrine sequelae that occurred following pinealectomy. Most attempts to induce melanocytic response to melatonin have failed in mammals; this is partially due to the inability of mammalian melanophores to cause lightening by intracellular aggregation of the dermal pigment. In place of dermatological actions, melatonin has come to exert effects on another neuroectodermal derivative, the brain. The pineal participates, through the secretion of melatonin, in the control of certain neuroendocrine and neurophysiological rhythms; it also mediates some of the effects of light on gonadal maturation, the ovulatory cycle, and the secretion of pituitary hormones.

30 citations

Journal ArticleDOI
TL;DR: The autonomic afferent pineal innervation in lizards, now for the first time ultramicroscopically demonstrated, is involved in the regulation of the synthesis, secretion and release of chemical compounds at the level of the secretory rudimentary photoreceptor cells which can be considered the phylogenetic forerunners of the mammalian pinealocytes.

30 citations

Journal ArticleDOI
TL;DR: It is indicated that excess production of VEGF and NO in pineal gland in response to hypoxia may be involved in increased vascular permeability as evidenced by an enhanced leakage of rhodamine isothiocyanate (RhIC).
Abstract: This study examined the factors that may be involved in altering the function of pineal gland in hypoxic conditions. Adult Wistar rats were subjected to hypoxia and the pineal gland was examined for the mRNA and protein expression of hypoxia-inducible factor-1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), endothelial, neuronal and inducible nitric oxide synthase (eNOS, nNOS, iNOS) at 3 hr-14 days after hypoxic exposure by real time reverse transcription-polymerase chain reaction, Western blotting and immunohistochemistry. Upregulated mRNA and protein expression of HIF-1alpha, VEGF, eNOS, nNOS and iNOS was observed in response to hypoxia. VEGF concentrations as determined by enzyme immunoassay and nitric oxide (NO) production measured by colorimetric assay were significantly higher after hypoxic exposure when compared with the controls. Melatonin content of the pineal gland, as determined by ELISA, was significantly reduced after the hypoxic exposure. Dilated blood vessels expressing eNOS were observed in hypoxic rats. Cells immunoreactive for VEGF were identified as the astrocytes whereas those immunoreactive for iNOS were pinealocytes and macrophages. Our findings indicate that excess production of VEGF and NO in pineal gland in response to hypoxia may be involved in increased vascular permeability as evidenced by an enhanced leakage of rhodamine isothiocyanate (RhIC). The increased vascular permeability may allow free access of serum-derived substances in the pineal gland that may affect the secretory function of the pinealocytes. Administration of exogenous melatonin may be beneficial as it reduced VEGF concentration and NO production significantly in hypoxic rats, and leakage of RhIC was concomitantly reduced.

30 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202219
202116
202011
201915
201817