Pinealocyte

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

Melatonin adjusts the expression pattern of clock genes in the suprachiasmatic nucleus and induces antidepressant-like effect in a mouse model of seasonal affective disorder

Abstract: Recently, we have shown that C57BL/6J mice exhibit depression-like behavior under short photoperiod and suggested them as an animal model for investigating seasonal affective disorder (SAD). In this study, we tested if manipulations of the circadian clock with melatonin treatment could effectively modify depression-like and anxiety-like behaviors and brain serotonergic system in C57BL/6J mice. Under short photoperiods (8-h light/16-h dark), daily melatonin treatments 2 h before light offset have significantly altered the 24-h patterns of mRNA expression of circadian clock genes (per1, per2, bmal1 and clock) within the suprachiasmatic nuclei (SCN) mostly by increasing amplitude in their expressional rhythms without inducing robust phase shifts in them. Melatonin treatments altered the expression of genes of serotonergic neurotransmission in the dorsal raphe (tph2, sert, vmat2 and 5ht1a) and serotonin contents in the amygdala. Importantly, melatonin treatment reduced the immobility in forced swim test, a de...

Intrinsic neurons and neural connections of the pineal organ of the house sparrow, Passer domesticus , as revealed by anterograde and retrograde transport of horseradish peroxidase

Abstract: In Passer domesticus, intrapineal nerve cells were labeled by uptake of microiontophoretically administered horseradish peroxidase (HRP). Unipolar nerve cells with a dichotomously branching stem process are the main source of the dominant pinelaofugal component of the pineal tract, whereas multipolar and bipolar neurons appear to represent interneurons. HRP-labeled nerve fibers are observed in the distal division (end-piece) of the pineal organ; they can be regarded either as processes of intrapineal neurons or projections of pinealopetal axons originating from central neurons. Furthermore, scattered labeled nerve fibers occur in different portions of the pineal stalk. Nerve fibers containing HRP were also demonstrated in the medial and lateral divisions of the habenular complex and in the periventricular layer of the hypothalamus; these axons apparently represent anterogradely labeled pinealofugal elements. On the other hand, retrogradely labeled neurons were found in the medial habenular complex and in the periventricular hypothalamic gray near the paraventricular nucleus, indicating that the pineal organ receives a pinealopetal innervation arising from the central nervous system. Ultrastructurally, the neuropil of the pineal organ of P. domesticus displays single basal processes of pinealocytes containing synaptic ribbons in association with clear synaptic vesicles. Occasionally, conventional synapses were observed the presynaptic terminals of which exhibit granular inclusions. The pineal tract consisting of four to six spatially separated fiber bundles comprises mainly unmyelinated elements accompanied by only few myelinated axons. The functional role of the neural apparatus revealed in the present study is discussed in context with the humoral (hormonal) control of circadian functions; the latter type of activity has been shown to exist in the pineal organ of P. domesticus (Zimmerman 1976).

NeuroD1: developmental expression and regulated genes in the rodent pineal gland.

Abstract: NeuroD1/BETA2, a member of the bHLH transcription factor family, is known to influence the fate of specific neuronal, endocrine and retinal cells We report here that NeuroD1 mRNA is highly abundant in the developing and adult rat pineal gland Pineal expression begins in the 17-day embryo at which time it is also detectable in other brain regions Expression in the pineal gland increases during the embryonic period and is maintained thereafter at levels equivalent to those found in the cerebellum and retina In contrast, NeuroD1 mRNA decreases markedly in non-cerebellar brain regions during development Pineal NeuroD1 levels are similar during the day and night, and do not appear to be influenced by sympathetic neural input Gene expression analysis of the pineal glands from neonatal NeuroD1 knockout mice identifies 127 transcripts that are down-regulated (>twofold, p twofold, p < 005) According to quantitative RT-PCR, the most dramatically down-regulated gene is kinesin family member 5C (100-fold) and the most dramatically up-regulated gene is glutamic acid decarboxylase 1( fourfold) Other impacted transcripts encode proteins involved in differentiation, development, signal transduction and trafficking These findings represent the first step toward elucidating the role of NeuroD1 in the rodent pinealocyte

Photoreception and circadian clock system of the chicken pineal gland

Abstract: Chicken pinealocytes contain three major components of the circadian clock system: 1) a self-sustained oscillator, 2) a photic-input pathway to the oscillator, and 3) an overt output represented by the rhythmic production of melatonin. Even under cultured conditions of isolated pineal gland or dissociated pinealocytes, the input-oscillator-output functions are well maintained. Because of these experimental advantages, chicken pineal gland has been one of the best models for the study of the circadian clock system. Since the finding of a pineal-specific photoreceptive molecule, pinopsin, we have characterized the endogenous phototransduction pathway in the pinealocytes. On the other hand, despite the long history of chick pineal research, the molecular mechanism underlying the pineal clock oscillation has been largely unknown. Our recent characterization of the chick pineal clock genes strongly suggests that they constitute a transcription/translation-based autoregulatory feedback loop, which is very similar to that generating circadian rhythmicity in mammalian SCN.