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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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TL;DR: Direct synaptic innervation of pinealocytes was observed in the superficial pineal gland of the Mongolian gerbil by electron microscopy, which reveals a neuronal character of the pinealocyte and might underlie reports of action potentials in electrophysiological recordings from the gland.
Abstract: Direct synaptic innervation of pinealocytes was observed in the superficial pineal gland of the Mongolian gerbil (Meriones unguiculatus) by electron microscopy. This innervation consisted of nerve fibres terminating in boutons with clear transmitter vesicles with a diameter of 40–60 nm. The boutons made synaptic junctions with the cell membrane of the pinealocyte displaying thickenings of both the pre- and postsynaptic membranes. Such boutons persisted in the gland 1 week after removal of both superior cervical ganglia. In contrast, all the sympathetic boutons containing transmitter vesicles with a small dense core disappeared after ganglionectomy. This direct synaptic innervation reveals a neuronal character of the pinealocyte and might underlie reports of action potentials in electrophysiological recordings from the gland.

22 citations

Journal ArticleDOI
TL;DR: It is shown that catecholamines stimulate melatonin synthesis in bone marrow-derived dendritic cells and RAW 264.7 macrophages, opening the possibility that extra-pineal melatonin acts as an autocrine/paracrine signal in macrophage under resolution or tolerant phenotypes.
Abstract: Melatonin (5-methoxy-N-acetylserotonin), the pineal hormone, is also synthesized by immune-competent cells The pineal hormone signals darkness, while melatonin synthesized on demand by activated macrophages at any hour of the day acts locally, favoring regulatory/tolerant phenotypes Activation of β-adrenoceptors in pinealocytes is the main route for triggering melatonin synthesis However, despite the well-known role of β-adrenoceptors in the resolution macrophage phenotype (M2), and the relevance of macrophage synthesized melatonin in facilitating phagocytic activity, there is no information regarding whether activation of β-adrenoceptors would induce melatonin synthesis by monocytes Here we show that catecholamines stimulate melatonin synthesis in bone marrow-derived dendritic cells and RAW 2647 macrophages Activation of β-adrenoceptors promotes the synthesis of melatonin by stimulating cyclic AMP/protein kinase A (PKA) pathway and by activating the nuclear translocation of NF-κB Considering the great number of macrophages around sympathetic nerve terminals, and the relevance of this system for maintaining macrophages in stages compatible to low-grade inflammation, our data open the possibility that extra-pineal melatonin acts as an autocrine/paracrine signal in macrophages under resolution or tolerant phenotypes

22 citations

Journal ArticleDOI
TL;DR: The synaptic complexes of the rat pinealocytes are neither cholinergic nor adrenergic, and the synaptic vesicles do not originate from the rough or smooth endoplasmic reticulum, and possess some chemical resemblance to microtubules and microtubular bouquets.
Abstract: The synaptic complexes of the rat pinealocytes are neither cholinergic nor adrenergic. In the synaptic vesicles, a neurotransmitter carrier substance of lipid nature reacting with OsO4-Zn I2 mixture (similar to that present in both cholinergic and adrenergic vesicles) was not found. In addition, there were no indications of glucose-6-phosphatase or thiamine-pyrophosphatase activity in the synaptic vesicles. Thus, it appears that the synaptic vesicles do not originate from the rough or smooth endoplasmic reticulum. The synaptic ribbons do not contain carbohydrates, are of protein nature and possess some chemical resemblance to microtubules and microtubular bouquets. Appropriate ultracytochemical reactions have not shown detectable quantities of sodium and calcium ions in pinealocyte synaptic complexes.

22 citations

Journal ArticleDOI
TL;DR: The structure of the ovine pineal gland during prenatal development is studied in women and in men through the course of pregnancy and during the first trimester of pregnancy.
Abstract: The structure of the pineal gland of 32 clinically healthy ovine embryos at different stages of development was studied. Embryos were arranged in four age groups, each containing eight embryos (four males and four females), defined in terms of the most relevant histological features: group 1 (27 to 69 days of prenatal development), group 2 (70 to 97 days), group 3 (98 to 116 days), and group 4 (117 to 150 days). At around 30 days of prenatal life, according to topographic criteria, the pineal outline begins to differentiate into a dorsal evagination of the diencephalic medium line, close to the anterior and posterior commissures. The growth of the pineal is biphasic. The ontogenic-proliferative phase begins at 30 days and includes the invasion of ependymal cells and the proliferation of the pineal parenchyma cells. The hypertrophic-differentiation phase includes the volume increment of the pinealoblasts and their differentiation into pinealocytes; this occurs at around 118 days. At around 98 days, the gland acquires its definitive compact appearance due to 1) glandular growth in constant volume and 2) the obliteration of pineal recess. The glandular structure displays a parenchyma made up of pinealoblasts, interstitial cells, and cells containing pigment. The pineal stroma is structured in pseudolobes formed by reticular and collagen fiber septae, which constitute together the interstitial cell prolongation net, which is the support structure of the whole glandular cytology. Capillaries are detected all over the glandular surface, being more abundant in the medullary zone. At around 98 days of prenatal development, VIP (Vasoactive Intestinal Peptide) positive fibers, distributed around blood vessels and among pinealoblasts were detected.

22 citations

Journal ArticleDOI
TL;DR: The findings obtained with denervated pineal glands suggest that the regulation of pineal melatonin production by both α‐ and p‐adrenergic mechanisms is through receptors located on postsynaptic structures.
Abstract: The role played by postsynaptic alpha-adrenergic receptors in the stimulation of pineal melatonin production was investigated in the Syrian hamster. The studies were conducted using organ cultured pineal glands collected from both anatomically intact and superior cervical ganglionectomized hamsters. Results obtained indicate that phenylephrine, an alpha-adrenergic agonist, by itself has no effect in promoting melatonin production; however, it potentiates the stimulatory effects of isoproterenol, a beta-adrenergic agonist, on pineal melatonin production in nonoperated hamsters. Similar observations were obtained with pineal glands whose presynaptic terminals were removed by prior superior cervical ganglionectomy. However, a longer incubation time was required (4-6 hours vs. 2 hours) with pineal glands taken from ganglionectomized animals. Apparently, beta-adrenergic activation is an absolute requirement to stimulate pineal melatonin production, and an alpha-adrenergic receptor mechanism potentiates beta-adrenergic activation. In addition, the findings obtained with denervated pineal glands suggest that the regulation of pineal melatonin production by both alpha- and beta-adrenergic mechanisms is through receptors located on postsynaptic structures.

22 citations


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