Topic
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: Results suggest that protein kinase C, which is activated in the pinealocyte by the alpha-adrenergic agonist phenylephrine, is probably involved in the adrenergic regulation of cGMP accumulation at a step distal to receptor activation.
81 citations
TL;DR: The atypical high-during-the-day pattern of retinal AANAT1 activity may reflect an evolutionary adaptation that optimizes an autocrine/paracrine signaling role of melatonin in photoadaptation and phototransduction; alternatively, it might reflect an adaptation that broadens and enhances aromatic amine detoxification in the retina.
81 citations
TL;DR: Findings suggest that mechanisms involved in the perception of light and the transduction of this signal through the circadian axis has changed in teleosts possibly as a reflection of the photic environment in which they have evolved in.
Abstract: The aim of this study was to compare the circadian control of melatonin production in teleosts To do so, the effects of ophthalmectomy on circulating melatonin rhythms were studied along with ex vivo pineal culture in six different teleosts Results strongly suggested that the circadian control of melatonin production could have dramatically changed with at least three different systems being present in teleosts when one considers the photic regulation of pineal melatonin production First, salmonids presented a decentralized system in which the pineal gland responds directly to light independently of the eyes Then, in seabass and cod both the eyes and the pineal gland are required to sustain full night-time melatonin production Finally, a third type of circadian control of melatonin production is proposed in tilapia and catfish in which the pineal gland would not be light sensitive (or only slightly) and required the eyes to perceive light and inhibit melatonin synthesis Further studies (anatomical, ultrastructural, retinal projections) are needed to confirm these results Ex vivo experiments indirectly confirmed these results, as while the pineal gland responded normally to day-night rhythms in salmonids, seabass and cod, only very low levels were obtained at night in tilapia and no melatonin could be measured from isolated pineal glands in catfish Together, these findings suggest that mechanisms involved in the perception of light and the transduction of this signal through the circadian axis has changed in teleosts possibly as a reflection of the photic environment in which they have evolved in
81 citations
TL;DR: It is shown that the circadian timing of AANAT protein expression is regulated by rhythmic translation of A ANAT mRNA, which provides a novel aspect for achieving the circadian rhythmicity of vertebrate melatonin.
Abstract: The circadian rhythm of pineal melatonin requires the nocturnal increment of serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AANAT]) protein. To date, only limited information is available in the critical issue of how AANAT protein expression is up-regulated exclusively at night regardless of its species-specific mRNA profiles. Here we show that the circadian timing of AANAT protein expression is regulated by rhythmic translation of AANAT mRNA. This rhythmic control is mediated by both a highly conserved IRES (internal ribosome entry site) element within the AANAT 5' untranslated region and its partner hnRNP Q (heterogeneous nuclear ribonucleoprotein Q) with a peak in the middle of the night. Consistent with the enhancing role of hnRNP Q in AANAT IRES activities, knockdown of the hnRNP Q level elicited a dramatic decrease of peak amplitude in the AANAT protein profile parallel to reduced melatonin production in pinealocytes. This translational regulation of AANAT mRNA provides a novel aspect for achieving the circadian rhythmicity of vertebrate melatonin.
80 citations
TL;DR: Immunoblotting experiments showed that recoverin appears to belong to the family of proteins which are expressed in both retina and pineal organ and are highly conserved in the course of phylogeny, and may be involved in phototransduction in the directly light-sensitive pineal organs of poikilothermic vertebrates and birds.
79 citations