Pinealocyte

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

The Pineal Gland and Mammalian Photoperiodism

Abstract: The mammalian pineal gland appears to be a major endocrine component in the regulation of photoperiodic responses. The circadian pattern of secretion of the pineal hormone, melatonin, is regulated by

Atypical synergistic α1- and β-adrenergic regulation of adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in rat pinealocytes

Abstract: The adrenergic control of cAMP and 3′,5′-cyclic GMP (cGMP) in dispersed adult rat pinealocytes was investigated. Norepinephrine treatment increased cAMP and cGMP content 60- and 400-fold, respectively; both α- and β-adrenoceptors had to be activated for these responses to occur. β-Adrenergic stimulation alone produced only about 6- and 2-fold increase in cAMP and cGMP content, respectively. α-Adrenergic stimulation, which alone had no effect on either cyclic nucleotide concentration, markedly amplified the β-adrenergic stimulation of both cAMP and cGMP. The relative potency of α-adrenergic agonists and antagonists indicates the α1-subclass of adrenoceptors is involved. A role of α1-adrenoceptors in the control of pineal cAMP is consistent with published evidence of the presence of α1-adrenoceptors on pinealocytes and their role in the regulation of N-acetyltransferase activity and melatonin production. (Endocrinology 116: 2167–2173,1985)

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Abstract: The pineal gland of birds contains one or more circadian oscillators that play a major role in overall temporal organization. We have developed a flow-through culture system for the isolated pineal by which we can measure the release of melatonin continuously from superfused glands over long periods of time. Chicken pineals release melatonin rhythmically, and these rhythms persist in vitro with a circadian oscillation. In light cycles the release of melatonin is strongly rhythmic; however, in constant conditions the amplitude of the rhythm is lower and appears to be damping. Light has at least two effects upon the isolated pineal: cyclic light input synchronizes the rhythm, and acute light exposure at night rapidly inhibits melatonin release. The cultured avian pineal clearly offers great potential as a model system for the study of vertebrate circadian oscillators and may open the way for an analysis of mechanism.

Control of melatonin synthesis in the mammalian pineal gland: the critical role of serotonin acetylation.

Abstract: The large daily rhythm in circulating melatonin levels is a highly conserved feature of vertebrate physiology: high values always occur at night. The dynamics of the rhythm are controlled by the next-to-last enzyme in melatonin synthesis (serotonin → N-acetylserotonin → melatonin), arylalkylamine N-acetyltransferase (AANAT), the "melatonin rhythm enzyme". In vertebrate biology, AANAT plays a unique time-keeping role as the molecular interface between the environment and the hormonal signal of time, melatonin. This chapter describes the mammalian AANAT regulatory system, which includes the retina, neural structures, transsynaptic processes, and molecular events. In addition, special attention is paid to the functional characteristics of the systems which insure that the nocturnal increase in melatonin is an accurate and reliable indicator of the duration of the night, and why the melatonin rhythm is the most reliable output signal of the Mind's Clock.