Pinealocyte

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

Morphofunctional and signaling molecules overlap of the pineal gland and thymus: role and significance in aging

Abstract: Deficits in neuroendocrine-immune system functioning, including alterations in pineal and thymic glands, contribute to aging-associated diseases. This study looks at ageing-associated alterations in pineal and thymic gland functioning evaluating common signaling molecules present in both human and animal pinealocytes and thymocytes: endocrine cell markers (melatonin, serotonin, pCREB, AANAT, CGRP, VIP, chromogranin А); cell renovation markers (p53, AIF, Ki67), matrix metalloproteinases (MMP2, MMP9) and lymphocytes markers (CD4, CD5, CD8, CD20). Pineal melatonin is decreased, as is one of the melatonin pathway synthesis enzymes in the thymic gland. A further similarity is the increased MMPs levels evident over age in both glands. Significant differences are evident in cell renovation processes, which deteriorate more quickly in the aged thymus versus the pineal gland. Decreases in the number of pineal B-cells and thymic T-cells were also observed over aging. Collected data indicate that cellular involution of the pineal gland and thymus show many commonalities, but also significant changes in aging-associated proteins. It is proposed that such ageing-associated alterations in these two glands provide novel pharmaceutical targets for the wide array of medical conditions that are more likely to emerge over the course of ageing.

Expression of C-type natriuretic peptide in the bovine pineal gland.

Abstract: Recent studies have pointed to membrane-bound guanylyl cyclases (GCs) type A and type B in the rat pineal gland, which augment levels of cyclic GMP (cGMP) in response to atrial natriuretic peptide (ANP), brain-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). The present report demonstrates for the first time the expression of CNP in the bovine pineal gland. The CNP prohormone transcript (unlike pre-pro-ANP) was found by reverse transcriptase (RT)-PCR in bovine pineal extracts. CNP immunoreactivity (ir) was revealed in a subpopulation of pinealocytes in situ and in nearly all pinealocytes in culture. Electron microscopic immunohistochemical investigations showed the presence of CNP-ir in cytoplasmic vesicles, providing evidence for the potential secretion of this peptide by pineal cells. Furthermore, the CNP receptor (GC-B) and GC-A (receptor for ANP and BNP) were identified by RT-PCR. Although melatonin secretion was unaffected, natriuretic peptides were able to elevate markedly cGMP production in cultured bovine pinealocytes with a rank order of potency of CNP > BNP = ANP. These findings describe a tissue CNP system in the bovine pineal gland and suggest that CNP may be a local auto- or paracrine modulator of pineal function.

Pinealocyte dense-cored vesicles and synaptic ribbons: a correlative ultrastructural-biochemical investigation in rats and mice.

Abstract: Dense-cored vesicles (DCV) and synaptic ribbons (SR) were quantified in the pineal gland of the rat (Sprague-Dawley) and mouse (Sasco/ICR strain), and day/night differences in frequency of these organelles correlated with levels of indoles determined by high performance liquid chromatography (HPLC). There were significant day/night differences in levels of serotonin (5HT), 5-hydroxyindole acetic acid (5HIAA), N-acetyl-5HT, and melatonin in the rat gland. Melatonin and N-acetyl-5HT were not detectable in the mouse gland sampled every 4 h over the light:dark cycle. The concentrations of 5HT and 5HIAA (ng/microgram protein) were similar in light-adapted rats and mice, but these indoles did not exhibit a circadian rhythm in the mouse gland. Correlative ultrastructural/biochemical results suggest that DCV do not contain physiologically important stores of 5HT since 1) the mouse gland contains the same number of DCV as the rat during the daytime, but only one-tenth the levels of 5HT, 2) day/night 5HT levels do not vary in the mouse gland, but there is a significant nocturnal decline in DCV numbers, and 3) 5HT levels in the rat gland decline at night when DCV numbers increase. Numbers of SR were significantly elevated at night in the rat and mouse, and the frequency of this organelle was similar in both species. However, ribbon-type SR predominated in rat pinealocytes, whereas SR in the mouse were almost exclusively spherical in shape. Day/night differences in SR numbers in the mouse gland suggest that cellular mechanisms regulating the frequency of this organelle do not involve factors related to indole metabolism. Because of the lack of photoperiodic effects on indole metabolism in the mouse pineal gland, this species is a potentially important model to study the functional relationship of pinealocyte organelles to cyclical changes in pineal products other than indoles (e.g., peptide/protein factors).

Electron microscopic autoradiography for demonstration of pineal serotonin in rat.

Abstract: The fine localization of rat pineal serotonin has been studied by means of electron microscopic autoradiography. Two hours after the intravenous injection of tritium labelled 5-hydroxytryptophan, the location of large number of silver tangled threads is seen in the sympathetic nerve terminals. There is also a less specific accumulation of the silver grains in the pinealocytes, some appearing in the cytoplasmic organelles and some in the nucleus.

Crx broadly modulates the pineal transcriptome.

Abstract: Cone-rod homeobox (Crx) encodes Crx, a transcription factor expressed selectively in retinal photoreceptors and pinealocytes, the major cell type of the pineal gland. In this study, the influence of Crx on the mammalian pineal gland was studied by light and electron microscopy and by use of microarray and qRTPCR technology, thereby extending previous studies on selected genes (Furukawa et al. 1999). Deletion of Crx was not found to alter pineal morphology, but was found to broadly modulate the mouse pineal transcriptome, characterized by a>2-fold down-regulation of 543 genes and a>2-fold up-regulation of 745 genes (p<0.05). Of these, one of the most highly up-regulated (18-fold) was Hoxc4, a member of the Hox gene family, members of which are known to control gene expression cascades. During a 24-h period, a set of 51 genes exhibited differential day/night expression in pineal glands of wild-type animals; only eight of these were also day/night expressed in the Crx⁻/⁻ pineal gland. However, in the Crx⁻/⁻ pineal gland 41 genes exhibited differential night/day expression that was not seen in wild-type animals. These findings indicate that Crx broadly modulates the pineal transcriptome and also influences differential night/day gene expression in this tissue. Some effects of Crx deletion on the pineal transcriptome might be mediated by Hoxc4 up-regulation.