Regulation of glycogen content in rat pineal gland by norepinephrine

Eugenín, Eliseo A.; Sáez, Claudia G.; Garcés, Gladys; Sáez, Juan C.

doi:10.1016/s0006-8993(97)00273-4

Cited by 6 publications

(19 citation statements)

References 41 publications

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“…These two agents were separately pre‐applied to pineal glands to test the role of gap junctional communication in NE‐induced glycogenolytic response. As per our previous publication (Eugenin et al ), PAS staining to identify glycogen stores under control conditions was stronger in astrocytic cells and lighter in pinealocytes (Fig. a).…”

Section: Resultssupporting

confidence: 80%

“…Previously, we demonstrated that glycogen stores are mainly localized in astrocytes, and they are sensitive to degradation upon NE application (Eugenin et al ). Glycogen degradation induced by NE was mediated primarily by the activation of α 1 ‐adrenoreceptor, but not α 2 ‐, and β‐adrenoreceptors (Eugenin et al ). Nonetheless, activation of the β‐adrenoreceptor‐dependent pathway modulated the response induced by the activation of α 1 ‐adrenoreceptors, suggesting an active cross‐talk between these receptors (Eugenin et al ).…”

Section: Resultsmentioning

confidence: 85%

“…Glycogen stores are dynamic and are reduced during the dark periods (Kachi and Ito ), suggesting that sympathetic activity induces glycogen degradation. Our published data indicate that in the rat pineal gland, glycogen stores are localized mainly in astrocytes and less in pinealocytes (Eugenin et al ). NE induces a rapid reduction in the amount of pineal glycogen through activation of α 1 ‐ and β‐ adrenoreceptors (Eugenin et al ).…”

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confidence: 90%

“…Our published data indicate that in the rat pineal gland, glycogen stores are localized mainly in astrocytes and less in pinealocytes (Eugenin et al ). NE induces a rapid reduction in the amount of pineal glycogen through activation of α 1 ‐ and β‐ adrenoreceptors (Eugenin et al ). However, the mechanism of transmission of glycogenolytic signals into the entire gland is unknown.…”

mentioning

confidence: 90%

“…The activity of the pineal gland is driven by the suprachiasmatic nucleus, which regulates the phasic release of norepinephrine (NE) from sympathetic neurons (Colwell ; Colwell ). NE action is transduced post‐synaptically by β‐ and α 1 ‐ adrenoreceptors (Axelrod ; Klein et al ; Eugenin et al ), through which it induces synthesis and releases of melatonin, a hormone that is involved in the photoperiodic regulation of reproduction and several other physiologic functions (Reiter ).…”

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confidence: 99%

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Gap junctions coordinate the propagation of glycogenolysis induced by norepinephrine in the pineal gland

Eugenin

Valdebenito

Górska

et al. 2019

Journal of Neurochemistry

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Chemical and electrical synapses are the two major communication systems that permit cell‐to‐cell communication within the nervous system. Although most studies are focused on chemical synapses (glutamate, γ‐aminobutyric acid, and other neurotransmitters), clearly both types of synapses interact and cooperate to allow the coordination of several cell functions within the nervous system. The pineal gland has limited independent axonal innervation and not every cell has access to nerve terminals. Thus, additional communication systems, such as gap junctions, have been postulated to coordinate metabolism and signaling. Using acutely isolated glands and dissociated cells, we found that gap junctions spread glycogenolytic signals from cells containing adrenoreceptors to the entire gland lacking these receptors. Our data using glycogen and lactate quantification, electrical stimulation, and high‐performance liquid chromatography with electrochemical detection, demonstrate that gap junctional communication between cells of the rat pineal gland allows cell‐to‐cell propagation of norepinephrine‐induced signal that promotes glycogenolysis throughout the entire gland. Thus, the interplay of both synapses is essential for coordinating glycogen metabolism and lactate production in the pineal gland.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 85%

mentioning

confidence: 90%

mentioning

confidence: 90%

mentioning

confidence: 99%

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Gap junctions coordinate the propagation of glycogenolysis induced by norepinephrine in the pineal gland

Eugenin

Valdebenito

Górska

et al. 2019

Journal of Neurochemistry

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Morphological Studies of the Pineal Gland in the Common Gull (Larus canus) Reveal Uncommon Features of Pinealocytes

Przybylska‐Gornowicz

Lewczuk

Prusik

et al. 2012

The Anatomical Record

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The avian pineal is a directly photosensory organ taking part in the organization of the circadian and seasonal rhythms. It plays an important role in regulation of many behavior and physiological phenomena including migration. The aim of the study was to investigate morphology of the pineal organ in the common gull (Larus canus). The light and electron microscopic studies were performed on the pineals of juvenile birds living in natural conditions of the Baltic Sea coast, which have been untreatably injured during strong storms in autumn and qualified for euthanasia. The investigated pineals consisted of a wide, triangular, superficially localized distal part and a narrow, elongated proximal part, attached via the choroid plexus to the intercommissural region of the diencephalon. The accessory pineal tissue was localized caudally to the choroid plexus. Based on the histological criteria, the organ was classified as the solid-follicular type. Two types of cells of fotoreceptory line were distinguished: rudimentary-receptor pinealocytes and secretory pinealocytes. Both types of cells were characterized by unusual features, which have been not previously described in avian pinealocytes: the presence of paracrystalline structures in the basal processes and their endings, the storage of glycogen in the form of large accumulations and the arrangement of mitochondria in clusters. Further studies on other species of wild water birds dwelling in condition of cold seas are necessary to explain if the described features of pinealocytes are specific for genus Larus, family Laridae or a larger group of water birds living in similar environmental conditions. Anat Rec,

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