Pinealocyte

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

Novel features of hamster pinealocyte ultrastructure.

Abstract: Pineal glands from young adult hamsters ( Mesocricetus auratus Water-house) kept on a 12 : 12 light : dark photoperiod were examined by electron microscopy. Ultrastructural features of nuclei, mitochondria, and centrioles that have not been reported previously are presented in this paper. Of particular interest is the presence of modified centrioles in normal hamster pinealocytes.

Neuropeptide Y-lmmunoreactive Nerve Fibres in the Pineal Gland of the Macaque (Macaca fascicularis).

Abstract: The distribution of neuropeptide Y (NPY)- and the C-fianking peptide of NPY (CPON)-immunoreactive elements in the pineal gland of the macaque was investigated by means of immunohistochemistry. NPY- and CPON-immunoreactive nerve fibres were located in the precommissural nucleus, around the stria medullaris, and in the posterior commissure. NPY- and CPON-immunoreactive nerve fibres endowed with bulbous varicosities, were traced from the brain via the pineal stalk into the rostral part of the pineal gland. Furthermore, CPON-immunoreactive, and to a lesser extent NPY-immunoreactive nerve fibres, were distributed in the meninges, the choroid plexus and the vasculature related to the pineal organ. Nerve fibres located in the pineal capsule penetrated into the pineal parenchyma, where groups of individual fibres were found most often in an interlobular position. Occasionally, individual nerve fibres dispersed between the pinealocytes were observed. In contrast to the nerve fibres originating from the brain, those originating from the periphery were endowed with smaller immunoreactive nerve terminals. Another apparent difference was that the peripheral nerve fibres innervated only the caudal two-thirds of the gland, whereas the central fibres were found exclusively in the rostral part of the pineal organ. Rarely, positive neuronal-like cells were found in the pineal parenchyma. These results show the presence of a moderate number of NPY- and CPON-immunoreactive nerve fibres within the primate pineal organ and strongly indicate that the primate pineal gland is innervated by NPYergic nerve fibres originating from both a peripheral and a central source.

Characterization of serotonin uptake in isolated bovine pinealocyte suspensions.

Abstract: The uptake of radiolabeled serotonin as a function of concentration exhibited saturation when low (0.005-2 µM) concentrations of serotonin were used. Kinetics of the initial rate (30 s) of entry of radiolabeled serotonin into pinealocytes were examined using various concentrations of the substrate. The effects of temperature, changes in external ion concentrations, drugs, metabolic inhibitors, and other compounds on the uptake of serotonin were investigated. High concentrations (10 µM-5 mM) of serotonin appear to use amino acid transport systems, e.g., L-lysine, L-leucine, and L-alanine. Uptake is partially sodium dependent, temperature dependent, sensitive to metabolic inhibitors, and inhibited by various amino acids. Low concentrations (0.005-1 µM) of serotonin appear to use a highly specific, allosteric carrier for transport. Uptake is sodium dependent, temperature dependent, and sensitive to a variety of metabolic inhibitors.

The influence of luteinizing hormone-releasing hormone (LHRH) on the process of protein and/or peptide secretion characterized by the formation of granular vesicles in mammalian pinealocytes. Comparative in vitro study.

Abstract: In the present study, the effect of LHRH on the process of protein and/or peptide secretion characterized by the formation of granular vesicles has been studied by means of an in vitro system in the pinealocytes of three different species of rodents. LHRH has a strong influence on the activity of this process. However, this effect varies with the presence of noradrenaline (NA) in the medium and is not identical in the individual species studied. In the rat and mouse, for example, LHRH induces an increase in the number of granular vesicles when the pinealocytes are cultured in a NA-free medium, while, in contrast, in the hamster this stimulatory effect is found exclusively in the presence of NA. Moreover, in the pinealocytes of the mouse, in the presence of NA, LHRH shows an inhibitory effect on protein secretion.