Neuroanatomy: Problems in pineal physiology

Hastings, Michael

doi:10.1038/320576a0

Cited by 3 publications

(2 citation statements)

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“…According to Pavel and Goldstain [27], melatonin is a releasing hormone for epiphyseal arginin-vasotocyn. Later on, Hastings [28] concluded that indoles in general (and, in particular, melatonin) can be regulators of synthesis and secretion of a series of epiphyseal peptides (according to the modern concepts, the latter are rather numerous) [29 ]. Analyzing the interrelations between indolealkylamines and oligopeptides found in the same neuroendocrine r epiphyseal cells, Pevet [30] suggested that indoles modify permeability of the pinealocyte membranes for the peptides they synthesized, thus favoring their access into the circulation system.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms responsible for autocrine regulation of the epiphysis function

1998

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The effect of injection of exogenous melatonin on formation of the nocturnal peak of the melatonin concentration and intrapineal hormonogenesis was studied on mature male rats. It was shown that 3H-melatonin is selectively uptaken by pinealocytes, and the uptake intensity depends on the degree of saturation of an organism with exogenous melatonin. Exogenous melatonin exerts an inhibitory influence on the hormone self-production, at the same time apparently stimulating synthesis of epiphyseal peptides. The results can be considered an indication of the existence of an ultra-short connection between the mechanisms of production of epiphyseal indoles and peptides, which apparently plays an important role in autocrine regulation of the epiphyseal functions.

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Section: Discussionmentioning

confidence: 99%

Mechanisms responsible for autocrine regulation of the epiphysis function

1998

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“…Whatever the case may be, it is sufficient to point out here that two things will be necessary to prove this hypothesis: 1) a n eventual morphological demonstration of the terminal pinealocyte endings in the habenular nucleus and the posterior commissure as reported by Korf et al (1986), and 2) a demonstration that these are indeed processes of the pinealocytes and not of aberrant intrapineal neurons. Recent comments by Hastings (1986) on this newly proposed theory of Korf et al (1986) are thought provoking.…”

Section: Innervationmentioning

confidence: 94%

Ultrastructure of the pineal body of the common vampire bat, Desmodus rotundus

Bhatnagar

1988

Am. J. Anat.

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The type AB pineal body of the common vampire bat, Desmodus rotundus, was recessed and lobulated, was extensively vascularized and intimately related to great veins, and was unassociated with the epithalamic region. The habenular and the posterior commissures coursed anteriorly and were unassociated with the pineal. The saccular suprapineal recess of the third ventricle extended dorsally juxtaposed to the pineal body. These anatomical features are likely to make pinealectomies in the vampire more difficult to manage. The pineal parenchyma consisted of light pinealocytes surrounded by canaliculi of various sizes, often transmitting unmyelinated nerve fibers and glial processes. Desmosomes were common. The pinealocyte nuclei were large and highly infolded; characteristic cytoplasmic constituents included abundant dilated Golgi complexes associated with clear vesicles, numerous polyribosomes, few single cisternae of ribosome-studded rough endoplasmic reticulum, mitochondria, and occasional multivesicular bodies and lysosomes. Almost all pinealocytes exhibited centrioles and some, in addition, displayed basal bodies but rarely ciliary shafts. A conspicuous feature of the pinealocyte cytoplasm was the presence of branched bundles of intermediate filaments, especially in the perinuclear zone. Siderotic macrophages, lipofuscin-pigment-containing phagocytic cells, mast cells, myelin bodies, and both fenestrated and continuous capillaries were present. The perivascular compartment was densely packed with unmyelinated nerve bundles containing small to large fibers exhibiting axoaxonic densities. Other constituents of the perivascular compartment were club-shaped pinealocyte processes filled with clear vesicles, microtubules, an occasional mitochondrion, glial processes, and collagen fibers. "Synapselike" contacts were observed between the axons and pinealocyte processes. Abundant pinocytotic vesicles in the capillary endothelium indicated active pinocytosis. Myelinated nerve fibers were lacking. The pineal ultrastructure of Desmodus is in part unlike that reported for other mammals, including bats.

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Localization of hydroxyindole O-methyltransferase-synthesizing cells in bovine epithalamus: immunocytochemistry and in-situ hybridization

Sato

Deguchi

Ichikawa³

et al. 1991

Cell Tissue Res

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Hydroxyindole O-methyltransferase (HIOMT)-immunoreactive cells and melatonin synthesis were demonstrated in bovine epithalamus (including the pineal gland) with monoclonal antibodies and cRNA probes to HIOMT. The HIOMT-immunoreactive product was present in the cytoplasm of pinealocytes. All identifiable pinealocytes were clearly labeled in the pineal gland. The expression of the HIOMT gene was first identified in pinealocyte cytoplasm by in-situ hybridization (ISH). The distribution of the hybridization-positive cells in the pineal gland was compatible with that revealed by immunocytochemistry using the monoclonal antibody to HIOMT. In addition, HIOMT transcripts were found in the medial habenular nucleus, and the habenular and posterior commissure; they may correspond to S-antigen-immunoreactive cells demonstrated in the same regions of the hamster and the mouse. In these regions, the hybridization-positive cells did not exhibit HIOMT-immunoreactivity; thus, cells devoid of immunoreactivity may synthesize but rapidly transport the newly synthesized proteins. These results indicate (1) that the conversion of N-acetylserotonin into melatonin takes place in the cytoplasm of pinealocytes, (2) that some epithalamic cells in the habenular area may synthesize melatonin, and (3) that melatonin may act as a chemical messenger in centrally directed processes, as shown by using S-antigen immunocytochemistry.

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Neuroanatomy: Problems in pineal physiology

Cited by 3 publications

References 0 publications

Mechanisms responsible for autocrine regulation of the epiphysis function

Mechanisms responsible for autocrine regulation of the epiphysis function

Ultrastructure of the pineal body of the common vampire bat, Desmodus rotundus

Localization of hydroxyindole O-methyltransferase-synthesizing cells in bovine epithalamus: immunocytochemistry and in-situ hybridization

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