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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: This work reviews the fish pineal and retinal melatonin rhythm generating systems and considers the evolutional pressures and other factors which led to these differences.
Abstract: Complete melatonin rhythm generating systems, including photodetector, circadian clock and melatonin synthesis machinery, are located within individual photoreceptor cells in two sites in Teleost fish: the pineal organ and retina. In both, light regulates daily variations in melatonin secretion by controlling the activity of arylalkylamine N-acetyltransferase (AANAT). However, in each species examined to date, marked differences exist between the two organs which may involve the genes encoding the photopigments, genes encoding AANAT, the times of day at which AANAT activity and melatonin production peak and the developmental schedule. We review the fish pineal and retinal melatonin rhythm generating systems and consider the evolutional pressures and other factors which led to these differences.

98 citations

Journal ArticleDOI
TL;DR: Melatonin-induced facilitation of the extinction of learned responses may be related to the observed rise in brain CAs and 5-HT after melatonin administration over days, which is thought to be inseparable from the actions of other neuropeptides and central neurotransmitters.

98 citations

Journal ArticleDOI
TL;DR: In this paper, the pineal glands possess both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind lipopolysaccharide (LPS) and trigger the NFKB pathway.
Abstract: Nuclear factor-kappa B (NFKB), a pivotal player in inflammatory responses, is constitutively expressed in the pineal gland. Corticosterone inhibits pineal NFKB leading to an enhancement of melatonin production, while tumor necrosis factor (TNF) leads to inhibition of Aa-nat transcription and the production of N-acetylserotonin in cultured glands. The reduction in nocturnal melatonin surge favors the mounting of the inflammatory response. Despite these data, there is no clear evidence of the ability of the pineal gland to recognize molecules that signal infection. This study investigated whether the rat pineal gland expresses receptors for lipopolysaccharide (LPS), the endotoxin from the membranes of Gram-negative bacteria, and to establish the mechanism of action of LPS. Here, we show that pineal glands possess both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind LPS and trigger the NFKB pathway. LPS induced the nuclear translocation of p50/p50 and p50/RELA dimers and the synthesis of TNF. The maximal expression of TNF in cultured glands coincides with an increase in the expression of TNF receptor 1 (TNFR1) in isolated pinealocytes. In addition, LPS inhibited the synthesis of N-acetylserotonin and melatonin. Therefore, the pineal gland transduces Gram-negative endotoxin stimulation by producing TNF and inhibiting melatonin synthesis. Here, we provide evidence to reinforce the idea of an immune-pineal axis, showing that the pineal gland is a constitutive player in the innate immune response.

98 citations

Journal ArticleDOI
TL;DR: The ultrastructural changes in the light pinealocytes occurring after sympathectomy and after continuous illumination was striking, and it is supposed that these changes have a common cause, the lack of free noradrenaline, the pinealotropic neurotransmitter.
Abstract: The ultrastructure of the rabbit pineal gland was investigated after sympathectomy (extirpation or decentralization of the superior cervical ganglia), parasympathectomy, continuous illumination and continuous darkness. The similarity of the ultrastructural changes in the light pinealocytes occurring after sympathectomy and after continuous illumination was striking. It is supposed that these changes have a common cause,viz. the lack of free noradrenaline, the pinealotropic neurotransmitter.

97 citations

Journal ArticleDOI
TL;DR: ’The pineal gland functions as a neuroendocrine “transducer” by translating the most basic environmental information into signals which modulate most neuro endocrine mechanisms.
Abstract: Earlier work in our laboratory led to the proposition that lymphocyte products act as messengers to the central nervous system.’ Those findings, which have been recently confirmed and extended,’,’ originated from the observation that antigens evoke specific and rapid hormonal responses early after injection into mice. We could demonstrate that the interference with those endocrine changes by a combination of psychotropic drugs specifically depressed humoral and cellular immune responseseh In the course of those studies, however, the idea progressively emerged that another basic modulator of neuroendocrine mechanisms, namely the pineal gland, plays a fundamental role in neuroimmunomodulation besides the better known hypothalamicpituitary system.’ The pineal gland functions as a neuroendocrine “transducer” by translating the most basic environmental information (photic, thermic, magnetic) into signals which modulate most neuroendocrine mechanisms.’.* This remarkable task seems to be accomplished via the circadian synthesis and release of melatonin (N-acetyl-5-methoxytryptamine), the most studied and best known pineal neurohormone. Melatonin is synthesized and released upon activation of pineal beta-adrenergic receptors in man and most vertebrates during the nocturnal, dark hours and maintains a consistently regular circadian rhythm? In humans, alterations of this rhythm have been associated with sleep disturbances, anxiety states, affective disorders, and psychosomatic diseases.I0.I1 Scant experimental findings exist on a possible connection between the pineal gland and the lymphohemopoietic system.” It has been reported that immune reactivity and circulating lymphocytes fluctuate according to a circadian r h ~ t h m , ’ ~ ’ ~ although the significance of these variations is not clear. Evidence for an inhibitory role of the pineal gland on carcinogenesis and tumor growth has also been reported (reviewed in Ref. 16). Recently, our early pharmacologic studies on the pineal-immune system connections’ have been replicated by other authors and our results have been confirmed.”

97 citations


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