The effect of treatment with melatonin upon the ultrastructure of the mouse pineal gland: a quantitative study

Redins, G. M.; Redins, C A; Novaes, J C

doi:10.1590/s1519-69842001000400018

Cited by 6 publications

(3 citation statements)

References 15 publications

(17 reference statements)

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“…Neuronal damage in the pineal gland due to stress and other factors (like sleep deprivation) could be alleviated by exogenous MEL administration (Lan et al, 2001). On the other hand, Redins et al (2001) noted a decrease in lysosomal number in mice exogenously treated with MEL. Conversely, the increased number of lysosomes could be indicative of decreased MEL synthesis which was also observed after arecolin treatment in the present experiment.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural and hormonal changes in the pineal–testicular axis following arecoline administration in rats

et al. 2007

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Arecoline is an alkaloid of betel nut of Areca catechu. Betel nut is chewed by millions of people in the world and it causes oral and hepatic cancers in human. It has therapeutic value for the treatment of Alzheimer and schizophrenia. Arecoline has immunosuppressive, mutagenic and genotoxic effects in laboratory animals. It also affects endocrine functions. The objective of this study was to investigate the effects of arecoline on pineal-testicular axis in rats. Since pineal activity is different between day and night, the current study is undertaken in both the photophase and scotophase. The findings were evaluated by ultrastructural and hormonal studies of pineal and testicular Leydig cells, with quantitations of fructose and sialic acid of sex accessories. Arecoline treatment (10 mg/kg body weight daily for 10 days) caused suppression of pineal activity at ultrastructural level by showing dilatation of the cisternae of the rough endoplasmic reticulum (RER), large autophagosome-like bodies with swollen mitochondrial cristae, numerous lysosomes, degenerated synaptic ribbons and reduced number of synaptic-like microvesicles. Moreover, pineal and serum N-acetylserotonin and melatonin levels were decreased with increased serotonin levels in both the gland and serum. In contrast, testicular Leydig cell activity was stimulated with abundance of smooth endoplasmic reticulum (SER), electron-dense core vesicles and vacuolated secretory vesicles, and increased testosterone level in the arecoline recipients. Consequently, the testosterone target, like prostate, was ultrastructurally stimulated with abundance of RER and accumulation of secretory vesicles. Fructose and sialic acid concentrations were also significantly increased respectively in the coagulating gland and seminal vesicle. These results were more significant in the scotophase than the photophase. The findings suggest that arecoline inhibits pineal activity, but stimulates testicular function (testosterone level) and its target organs presumably via muscarinic cholinergic receptor in rats.

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Section: Discussionmentioning

confidence: 99%

Ultrastructural and hormonal changes in the pineal–testicular axis following arecoline administration in rats

et al. 2007

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“…Sympathectomy is known to suppress the synthesis and secretion of melatonin [10]. Administration of exogenous melatonin [11], stress [12] and hypobaric hypoxia [13] also influence the secretory activity of pinealocytes. Another factor, glutamate, has recently been thought to mediate the secretory activity of the pineal gland [14, 15].…”

Section: Introductionmentioning

confidence: 99%

Expression of N‐methyl‐D‐aspartate (NMDA) and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) GluR2/3 receptors in the developing rat pineal gland

Kaur¹,

Sivakumar²,

Ling³

2005

Journal of Pineal Research

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The expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) type glutamate (GluR2/3) receptors and N-methyl-D-aspartate receptor subtype 1 (NMDAR1) was carried out by immunohistochemistry, double immunofluorescence and real-time RT-PCR analysis in the pineal glands of 1-day to 6-wk-old rats in the present study. GluR2/3 immunopositive cells were distributed throughout the pineal gland and showed branching processes in all age groups. The NMDAR1 immunoreactivity, however, was observed in fewer branched cells. A constitutive mRNA expression of NMDAR1, GluR2 and GluR3 was detected in the pineal glands of various ages and showed no significant difference between the age groups studied. Immunohistochemical and double immunofluorescence results showed that the GluR2/3 were mainly expressed and co-localized with OX-42-positive microglia/macrophages and the glial fibrillary acidic protein (GFAP)-positive astrocytes. Co-localization of NMDAR1 with OX-42- and GFAP-positive cells was much less. The expression of these receptors on the glial cells suggests that they may be involved in the development and growth of the pineal gland in the early postnatal period (1 day to 3 wk) and subsequently in the regulation of melatonin synthesis.

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“…Thus, in Leydig cells of mice treated with melatonin the lysosomes should be involved in controlling the synthesis and release of secretory products. In mice pinealocytes treated with melatonin, we noticed an apparent inhibition of the secretory activity of the pineal gland as well as an increase in lysosome number and fractional volume (Redins et al, 2001).…”

Section: Tablementioning

confidence: 83%

The effects of treatment with melatonin on the ultrastructure of mouse leydig cells: a quantitative study

Redins

Redins²,

Novaes

2002

Braz. J. Biol.

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Both the presence of receptors for gonadal steroids in the pineal gland and in vitro observations of direct action of melatonin upon Leydig cells, inhibiting testosterone secretion, indicate a direct connection between pineal gland and gonadal function. In the present study, we used a transmission electron microscope to analyze the morphologic parameters of Leydig cells from adult Swiss outbred white mice treated with daily subcutaneous injections of 100 micrograms of melatonin (N-acetyl, 5-methoxytryptamine), during 22 consecutive days, compared with sham-control animals which had only received the melatonin vehicle. The melatonin group of mice showed a decrease in nuclear volume and fractional nuclear volume; smooth and rough endoplasmic reticulum; mitochondria; and Golgi complex. Our data also showed an increase in cytoplasmic volume, fractional cytoplasmic volume, and lysosomes in these same animals. The results suggest that melatonin, directly or indirectly, alters the ultrastructure of mouse Leydig cells and possibly influences their secretory activity by inhibiting their capacity to secrete steroids.

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The effect of treatment with melatonin upon the ultrastructure of the mouse pineal gland: a quantitative study

Cited by 6 publications

References 15 publications

Ultrastructural and hormonal changes in the pineal–testicular axis following arecoline administration in rats

Ultrastructural and hormonal changes in the pineal–testicular axis following arecoline administration in rats

Expression of N‐methyl‐D‐aspartate (NMDA) and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) GluR2/3 receptors in the developing rat pineal gland

The effects of treatment with melatonin on the ultrastructure of mouse leydig cells: a quantitative study

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