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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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TL;DR: The pineal organs of 14-week-old domestic geese were investigated with light and electron microscopy and a prominent feature of all types of goose pinealocytes was the presence of numerous dense core vesicles.
Abstract: The pineal organs of 14-week-old domestic geese were investigated with light and electron microscopy. The pineals consisted of a wide distal part and a narrow middle-proximal one. The glands were attached to the intercommissural region via the choroid plexus. The pineal parenchyma was formed by round or elongated follicles. The follicular wall was composed predominantly by cells immunoreactive with antibodies against hydroxyindolo-O-methyltransferase (HIOMT) or glial fibrillary acid protein (GFAP). They formed two or more layers. HIOMT-positive elements were represented by elongated cells bordering the follicular lumen and oval cells located in the external layer of the follicular wall. These cells were identified in ultrastructural studies as rudimentary-receptor pinealocytes and secretory pinealocytes, respectively. Among rudimentary-receptor pinealocytes two types of cells, designed as A and B, were distinguished due to structural differences. Type A cells extended through the whole follicular wall and showed regular stratified distribution of organelles in well-recognizable zones with rough endoplasmic reticulum, the Golgi apparatus and mitochondria. Type B cells, like type A pinealocytes, contacted the pineal lumen and showed polarity of their internal structure. However, they were markedly shorter than the cells of type A and lacked stratified distribution of organelles. Secretory pinealocytes contained irregularly dispersed organelles. A prominent feature of all types of goose pinealocytes was the presence of numerous dense core vesicles. The population of GFAP-positive cells consisted of ependymal-like supporting cells and astrocyte-like cells.

19 citations

Journal ArticleDOI
TL;DR: Pinealocytes of female pigs were studied electron-microscopically and compared with those of other mammals to find out the role of dense-cored vesicles and membrane-bounded bodies in secretory processes of pinealocytes.
Abstract: Pinealocytes of female pigs were studied electron-microscopically and compared with those of other mammals. A prominent Golgi apparatus forming dense-cored vesicles was widely dispersed in the cytoplasm of the cell body. A very characteristic feature of the pig pinealocytes was the presence of membrane-bounded bodies showing wide variations in internal structure. Possible roles of the dense-cored vesicles and membrane-bounded bodies in secretory processes of pinealocytes are discussed.

19 citations

Journal ArticleDOI
TL;DR: Rat pineal 5'-deiodinase activity in the rat pineal gland follows a nyctohemeral profile, exhibiting basal values during the day and maximal values at night, and both in vivo and in vitro studies show that beta-adrenergic receptors are primarily involved in the activation of the enzyme.

19 citations

Journal ArticleDOI
TL;DR: It is demonstrated that purinergic signaling differentially modulates NAS andmelatonin synthesis and point to a regulatory role for ATP as a cotransmitter in the control of ASMT, the rate‐limiting enzyme in melatonin synthesis.
Abstract: Adenosine triphosphate (ATP) is released onto the pinealocyte, along with noradrenaline, from sympathetic neurons and triggers P2Y1 receptors that enhance β-adrenergic-induced N-acetylserotonin (NAS) synthesis. Nevertheless, the biotransformation of NAS into melatonin, which occurs due to the subsequent methylation by acetylserotonin O-methyltransferase (ASMT; EC 2.1.1.4), has not yet been evaluated in the presence of purinergic stimulation. We therefore evaluated the effects of purinergic signaling on melatonin synthesis induced by β-adrenergic stimulation. ATP increased NAS levels, but, surprisingly, inhibited melatonin synthesis in an inverse, concentration-dependent manner. Our results demonstrate that enhanced NAS levels, which depend on phospholipase C (PLC) activity (but not the induction of gene transcription), are a post-translational effect. By contrast, melatonin reduction is related to an ASMT inhibition of expression at both the gene transcription and protein levels. These results were independent of nuclear factor-kappa B (NF-kB) translocation. Neither the P2Y1 receptor activation nor the PLC-mediated pathway was involved in the decrease in melatonin, indicating that ATP regulates pineal metabolism through different mechanisms. Taken together, our data demonstrate that purinergic signaling differentially modulates NAS and melatonin synthesis and point to a regulatory role for ATP as a cotransmitter in the control of ASMT, the rate-limiting enzyme in melatonin synthesis. The endogenous production of melatonin regulates defense responses; therefore, understanding the mechanisms involving ASMT regulation might provide novel insights into the development and progression of neurological disorders since melatonin presents anti-inflammatory, neuroprotective, and neurogenic effects.

19 citations

Journal ArticleDOI
TL;DR: An electron microscopic study of a pineal gland which had been obtained from, a 3‐year‐old girl at autopsy revealed the presence of synaptic ribbon in it, and this finding may offer a meaningful information which discloses a part of the real function of the pineal organ in man.
Abstract: An electron microscopic study of a pineal gland which had been obtained from, a 3-year-old girl at autopsy revealed the presence of synaptic ribbon in it. Namely, in some parenchymal cells observed, synaptic ribbons, each of which was ca. 700 nm in length and with synaptic vesicles of up to 60 nm in diameter gathering on the surface, were found in the cytoplasmic area adjacent to the cell membrane. The substructure of the synaptic ribbon, i.e., parallel striae running inside along the longitudinal direction, was definitely observed. There is a hypothesis which has been almost accepted that the mammalian pinealocyte is homologous to the photoreceptor cell of the pineal organ in lower animals, and one of the morphological evidences which supports this speculation is the presence of sensory cell elements in both. Since, this kind of work has been hardly done with human materials, the above finding may offer a meaningful information which discloses a part of the real function of the pineal gland in man.

19 citations


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