Morphofunctional aspects of the mammalian pineal gland

Karasek, M; Reíter, Russel J.

doi:10.1002/jemt.1070210206

Cited by 26 publications

(14 citation statements)

References 96 publications

(114 reference statements)

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“…At least two kinds of secretory vesicle-like organelles have been identified in pinealocytes: dense core granules, which are speculated to be involved in the storage and secretion of melatonin and some neuropeptides such as arginine vasotocin (3,4), and a large number of synaptic-like microvesicles (MVs) 1 containing synaptophysin (5). Although histochemical evidence indicated that MVs are distinct from neuronal synaptic vesicles in their lack of synapsin I, the possible participation of MVs in some secretory pathways in pinealocytes was also speculated (5).…”

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confidence: 99%

Vesicular L-Glutamate Transporter in Microvesicles from Bovine Pineal Glands

Moriyama

Yamamoto

1995

Journal of Biological Chemistry

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Pinealocytes, endocrine cells that synthesize and secrete melatonin, possess a large number of synaptic-like microvesicles (MVs) containing the L-glutamate transporter (Moriyama, Y., and Yamamoto, A. (1995) FEBS Lett., 367, 233-236). In this study, the L-glutamate transporter in MVs isolated from bovine pineal glands was characterized as to its driving force, requirement of anions, and substrate specificity. Upon the addition of ATP, the MVs accumulated L-glutamate. The uptake was significantly dependent on the extravesicular Cl ؊ concentration, being negligible in the absence of Cl ؊ and maximum at 2-5 mM and decreasing gradually at 20 -100 mM. The membrane potential (inside positive) was maximum at 0 -10 mM Cl ؊ and then decreased gradually depending on the Cl ؊ concentration, whereas a pH gradient was practically absent without Cl ؊ and increased gradually up to 100 mM Cl ؊ . Ammonium acetate or nigericin plus K ؉ , a dissipator of a pH gradient, had little effect on or was slightly stimulatory toward the uptake, whereas valinomycin plus K ؉ inhibited both formation of the membrane potential and the glutamate uptake to similar extents. The ATP-and Cl ؊ -dependent glutamate uptake was inhibited by fluoride, iodide, or thiocyanate, without vacuolar H ؉ -ATPase being affected. An anion channel blocker, 4,4-diisothiocyanatostilbene-2,2-disulfonic acid, similarly inhibited the glutamate uptake in a Cl ؊ protectable manner. Furthermore, ATP-and glutamate-dependent acidification of MVs was observed when 4 mM Cl ؊ was present. Among more than 50 kinds of glutamate analogues tested, only a few compounds, including 1-aminocyclohexane-trans-1,3-dicarboxylic acid, caused similar acidification. A good correlation was observed between the acidification and the inhibition of glutamate uptake by glutamate analogues. These results indicated that 1) the major driving force of the glutamate uptake is the membrane potential, 2) Cl ؊ regulates the glutamate uptake, probably via anion-binding site(s) on the transporter, and 3) the transporter shows strict substrate specificity. Hence, the overall properties of the vesicular glutamate transporter in the MVs well matched those of the synaptic vesicle glutamate transporter. We concluded that the vesicular glutamate transporter, being similar if not identical to the neuronal counterpart, operates in endocrine cells.Pinealocytes are parenchymal endocrine cells of pineal glands that synthesize and secrete melatonin into the blood (1-3). At least two kinds of secretory vesicle-like organelles have been identified in pinealocytes: dense core granules, which are speculated to be involved in the storage and secretion of melatonin and some neuropeptides such as arginine vasotocin (3, 4), and a large number of synaptic-like microvesicles (MVs) 1 containing synaptophysin (5). Although histochemical evidence indicated that MVs are distinct from neuronal synaptic vesicles in their lack of synapsin I, the possible participation of MVs in some secretory pathways in pinealocytes was also speculated...

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confidence: 99%

Vesicular L-Glutamate Transporter in Microvesicles from Bovine Pineal Glands

Moriyama

Yamamoto

1995

Journal of Biological Chemistry

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“…Its long-term functional "inoperativeness" leads to the release of some ribosomes, complexation of GER cisternae, and secretion of vesicles with a fl occulent agent. These changes illustrate ependymal secretion and suppression of the neurosecretion-like mechanism [8].…”

Section: Resultsmentioning

confidence: 99%

“…Here we studied changes in rat pineal gland after 45 and 90 days of 24-h exposure to bright light. The standard morphological markers served as the index of functional activity of the pineal gland [8].…”

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confidence: 99%

Morphological Changes in the Pineal Gland of Rats under Conditions of Long-Term Exposure to Bright Light

2010

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Changes in the diurnal light cycle affect the morphofunctional state of the pineal gland. The volume of the nucleus, Golgi apparatus, and mitochondria in pinealocytes decreases after 45-day exposure to bright light. After 90 days, the degree of nuclear polymorphism increased, the specific volume of the Golgi apparatus returned to normal, the volume of the granular endoplasmic reticulum decreased, while the volume of lysosomes, free ribosomes, and polysomes increased. These changes reflect plasticity of pinealocytes and adaptation of the gland to long-term 24-h light exposure.

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“…Taking into account the observed increase in the number of vesi cles with osmiophilic inclusions occurring at the new moon (and at the background of hyperplasia of dic tyosomes and an expanding area of the Golgi complex), one can speculate that the vesicles carrying dense inclu sions are formed owing to the Golgi complex of pinealo cytes. It is generally accepted that the functional state of the pineal endocrine cells -light pinealocytes (LP) and dark pinealocytes (DP) -is different [1,2,16]. The observed lunar phase dependent morphological changes can be a reflection of the shifts in the functional state of the pineal gland.…”

Section: Discussionmentioning

confidence: 99%

Pineal gland as an endocrine gravitational lunasensor: Manifestation of moon-phase dependent morphological changes in mice

Герасимов

Kostyuchenko

Solovieva

et al. 2014

Biochemistry Moscow

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We found that some morphological properties of the pineal gland and submandibular salivary gland of mice are significantly distinct at the new and full moon. We suppose that the differences are initiated by the displacements of the electron-dense concretions in the secretory vesicles of pinealocytes. This presumably occurs under the influence of the gravitational field, which periodically changes during different phases of the moon. It seems that the pinealocyte is both an endocrine and gravisensory cell. A periodic secretion of the pineal gland probably stimulates, in a lunaphasic mode, the neuroendocrine system that, in turn, periodically exerts influence on different organs of the body. The observed effect probably serves, within the lifelong clock of a brain, to control development and aging in time.

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Morphofunctional aspects of the mammalian pineal gland

Cited by 26 publications

References 96 publications

Vesicular L-Glutamate Transporter in Microvesicles from Bovine Pineal Glands

Vesicular L-Glutamate Transporter in Microvesicles from Bovine Pineal Glands

Morphological Changes in the Pineal Gland of Rats under Conditions of Long-Term Exposure to Bright Light

Pineal gland as an endocrine gravitational lunasensor: Manifestation of moon-phase dependent morphological changes in mice

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