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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: CAMP-dependent CREB phosphorylation could play a role in the adrenergic regulation of gene expression in pinealocytes, and in vivo studies show that CREBosphorylation can be induced by treatment with isoproterenol, demonstrating that phosphorylations of pineal CREB occurs in intact animals.
Abstract: Norepinephrine (NE) regulates melatonin production and many other aspects of pineal function through actions involving cAMP. In the present study the effects of NE on the phosphorylation of the cAMP response element-binding protein (CREB) were studied to determine whether CREB phosphorylation might be involved in cAMP signal transduction in this tissue. CREB was detected using gel mobility-shift analysis with the radiolabeled Ca2+/cAMP response element of the c-fos promoter. CREB phosphorylation was estimated in the gel mobility-shift assay using an antiserum specific for phosphorylated CREB. This antiserum generates a supershifted CREB signal with protein extracts obtained from glands treated with NE (EC50 approximately equal to 10 nM) in organ culture, demonstrating that NE stimulates CREB phosphorylation. CREB phosphorylation peaks 30-45 min after NE treatment is initiated and then gradually returns to base-line values. Pharmacological studies show that NE-stimulated CREB phosphorylation is mediated primarily through beta 1-adrenergic receptor-stimulated increases in cAMP. Activation of alpha 1-adrenergic receptors, which is known to elevate the intracellular free Ca2+ concentration, does not cause CREB phosphorylation. However, it is possible to produce CREB phosphorylation with certain pharmacological agents that elevate the intracellular free Ca2+ concentration. In vivo studies show that CREB phosphorylation can be induced by treatment with isoproterenol (1 mg/kg), demonstrating that phosphorylation of pineal CREB occurs in intact animals. These studies indicate that cAMP-dependent CREB phosphorylation could play a role in the adrenergic regulation of gene expression in pinealocytes.

155 citations

Journal ArticleDOI
TL;DR: This review focuses on melatonin’s role in two systems-the circadian system and the photoperiodic system because of the interrelationship between the circadian and photoperperiodic systems.
Abstract: first of these compounds isolated, and it had the interesting property of causing blanching of frog skin. A more important reason, however, arose from the belief that the terminal enzyme in the synthesis of melatonin, hydroxyindole-O-methyltransferase (HIOMT), was uniquely localized to pineal tissue. Consequently, melatonin and related methoxyindoles were, at least potentially, unique pineal products. Finally, interest in pineal products was generated because the pineal appeared to be involved in controlling important physiological functions, such as reproduction. Of the several related methoxyindoles, only 5-methoxytryptamine and 5-methoxytryptophol exhibit actions that, like those of melatonin, mimic certain influences of photoperiod on mammalian reproduction. Melatonin, however, appears to be at least 10 times more potent than any of the other naturally occurring methoxyindoles with respect to these actions (Reiter et al., 1975; Rollag, 1982; Goldman et al., 1984). This review focuses on melatonin’s role in two systems-the circadian system and the photoperiodic system. These two systems are discussed together because of the interrelationship between the circadian and photoperiodic systems: Many vertebrates utilize a circadian mechanism to measure daylength. A brief description of the structural evolution of the pineal and related organs is given as background for a more detailed discussion of melatonin’s role within the circadian and photoperiodic systems.

152 citations

Journal ArticleDOI
TL;DR: Intraperitoneal injection or subcutaneous implantation of melatonin in beeswax resulted in a vast increase in melatonin content in the retina and the Harderian gland of the juvenile and adult rats.

152 citations

Journal ArticleDOI
TL;DR: Rat SCN single-unit activity was inhibited by melatonin superfusion during the late subjective day in a dose-dependent manner but not at other times of day, supporting the view that melatonin acts directly on SCN neurons.

149 citations

Journal ArticleDOI
TL;DR: The presence of melatonin is demonstrated in the pineal gland, the retina and the Harderian gland in some mammalian and non-mammalian vertebrates, using a specific fluorescence labelled antibody technique.
Abstract: The presence of melatonin is demonstrated in the pineal gland, the retina and the Harderian gland in some mammalian and non-mammalian vertebrates, using a specific fluorescence labelled antibody technique. Four different potent antibodies against melatonin have been used and compared. In the pineal gland of hamsters, mice, rats and snakes, specific fluorescence, mostly restricted to the cytoplasm of the cells, is detected in pinealocytes. Fluorescence is also detected in the pineal organ of fishes, tortoises and lizards, but it has not been possible, from cryostat sections of fresh tissue, to assert which kind of cell is reacting (photoreceptor cells or interstitial ependymal cells). In the retina, fluorescence is almost exclusively restricted to the outer nuclear layer. In the Harderian gland of mammals and reptiles, fluorescence is localized in the secretory cells of the alveoli and mostly restricted to the cytoplasm surrounding the nucleus. These results are discussed in relation to the concept of melatonin synthesis at extrapineal sites independent of pineal production.

147 citations


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