Topic
Pinealocyte
About: Pinealocyte is a research topic. Over the lifetime, 1605 publications have been published within this topic receiving 55609 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: It is reported that SCN 2-DG uptake was inhibited by melatonin at CT10, when 1-14C]glucose uptake is normally high, and unaffected at CT14, when 2- DG uptake is Normally low, which indicates that the SCN may be neural substrates through which melatonin exerts at least some of its effects on mammalian physiology.
85 citations
TL;DR: It is demonstrated in humans and rats that thymus contains melatonin, expresses the mRNAs encoding N-acetyltransferase and hydroxyindol-O-methyltransferase, the two key enzymes of the melatonin synthesis, and has this biosynthetic machinery activated.
Abstract: Melatonin is an indoleamine widely distributed in the evolution that shows a great functional versatility, playing an important role as a transmitter of photoperiodic information and exhibiting antioxidant, oncostatic, anti-aging and immunomodulatory properties. In vertebrates, this molecule is produced by the pineal gland and other extrapineal sites. The present study was carried out to investigate the presence of melatonin in thymus and the possibility of an endogenous melatonin synthesis in this organ, in which T cells are matured. In this work, we demonstrate in humans and rats that thymus contains melatonin, expresses the mRNAs encoding N-acetyltransferase and hydroxyindol-O-methyltransferase, the two key enzymes of the melatonin synthesis, and has this biosynthetic machinery activated. In addition, rat thymocytes cultured for 24 h exhibited high levels of melatonin. The results presented here suggest that human and rat thymuses are able to synthesize melatonin, which could have intracrine, autocrine and paracrine functions.
84 citations
TL;DR: It is proposed that pineal chief cells share a common feature: they somehow transform the information derived from the light/dark cycle into daily rhythms of neural and hormonal output and appear invariably involved in the temporal organization of physiological and behavioral processes.
Abstract: Data on the cell biology of pineal transducers (chief cells: typical and modified photoreceptors, pinealocytes) which belong to the paraneuron family, are reviewed in the vertebrate series. In spite of major changes throughout phylogeny, it is proposed that pineal chief cells share a common feature: they somehow transform the information derived from the light/dark cycle into daily rhythms of neural (an excitatory neurotransmitter) and/or hormonal (melatoninergic) output and appear invariably involved in the temporal organization of physiological and behavioral processes.
84 citations
TL;DR: The ultrastructure of the human fetal pineal gland suggests that the gland has a secretory function in early intrauterine life and indicates the existence of a blood-brain barrier.
Abstract: The ultrastructure of the pineal gland of 18 human fetuses (crown-rump lengths 30–178 mm) was investigated. The pineal gland exhibits a pyramidal shape and consists of an anterior and posterior lobe. Only one parenchymal cell type, the pinealocyte, was observed. Few neuroblasts were seen between the pinealocytes and in the extended perivascular space. The pinealocytes possess all the organelles necessary for hormone synthesis. No specific secretory granule could be observed. The organ is abundantly vascularized and richly innervated. The morphology of the capillaries indicates the existence of a blood-brain barrier. The ultrastructure of the human fetal pineal gland suggests that the gland has a secretory function in early intrauterine life.
84 citations
TL;DR: An abrupt decrease in cyclic AMP may be the signal for the rapid decrease in pineal N-acetyltransferase activity, as indicated by the observation that the inhibitory effect of 1-propranolol on N- acetyl transferase was blocked by dibutyryl cyclicAMP and phosphodiesterase inhibitors.
Abstract: Dispersed pinealocytes have been used to study the role of adenosine 3',5'-monophosphate (cyclic AMP) in the "turnoff" of N-acetyltransferace activity. Activity was first stimulated 100-fold by treating cells with 1-norepinephrine. 1-Propranolol acted stereospecifically to rapidly reverse this, resulting in a 70 percent loss of enzyme activity within 15 minutes. An even more rapid 1-propranolol-induced decreased in cyclic AMP also occurred. This together with the observation that the inhibitory effect of 1-propranolol on N-acetyltransferase was blocked by dibutyryl cyclic AMP and phosphodiesterase inhibitors indicate that an abrupt decrease in cyclic AMP may be the signal for the rapid decrease in pineal N-acetyltransferase activity.
84 citations