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

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 µg 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

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

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.

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

In order to evaluate melatonin implication in the regulating of its own secretory process by pinealocytes, we used morphometric techniques for transmission electron microscopy. In mice treated with 100 mg of melatonin (N-acetyl-5-methoxy-tryptamine) by daily subcutaneous injection, we observed a decrease in number and volumetric density of lysosomes. Our results showed that melatonin influences the secretory activity of pinealocytes and participates in a complex secretory regulating mechanism

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

In order to evaluate melatonin implication in the regulating of its own secretory process by pinealocytes, we used morphometric techniques for transmission electron microscopy. In mice treated with 100 mg of melatonin (N-acetyl-5-methoxy-tryptamine) by daily subcutaneous injection, we observed a decrease in number and volumetric density of lysosomes. Our results showed that melatonin influences the secretory activity of pinealocytes and participates in a complex secretory regulating mechanism.

The effects of testosterone on the mice pinealocytes: a quantitative study.

In order to determine the effects of testosterone upon the function of the pineal gland we quantitated, under the electron microscope, the number of dense-core vesicles, lysosomes, lipid droplets and the fractional volume of the pineal gland components in adult male mice. We studied six groups of mice submitted to different treatments as follows: treated with testosterone propionate (0.1 mg/10 g body weight for 15 consecutive days), castrated and the respective control mice. In mice treated with testosterone we observed a decrease in the number and fractional volume of dense-core vesicles and an increase in the fractional volume of lysosomes and lipid droplets. In castrated mice, without treatment, we observed a decrease in the number of lysosomes and an increase in the number and fractional volume of dense-core vesicles. These results show that testosterone is closely related to the secretory process of mice pinealocytes, playing an inhibitory role upon the functional activity of the pineal gland.

[Morphological study of the pineal organ in the spined rat Proechimys iheringi Thomas, 1911]. / Estudo morfológico do órgáo pineal do rato-espinho Proechimys iheringi Thomas, 1911.

The pineal organ of the spined rat is located deeply near the third ventricle. The organ shows a compact pattern of organization with pinealocytes and astrocytes arranged in cords and rosettes. Numerous concretions positive to chrome alum hematoxylin technic are visualized in the adjacent tissue near the pineal organ and in the vicinity of the veins which drain the blood of the organ. In the present work we discuss the probable origin of these concretions.

Demonstration of actin in neurosecretory cells by treatment with nitrobenzoxadiazole-phallacidin.

Serial sections containing neurosecretory cells from chicken hypothalamus were cut after fixation in formaldehyde and embedding in paraffin. Sections were exposed to NBD-Ph (nitrobenzoxadiazole-phallacidin) and showed evidence of containing actin. By using a medium with sodium borohydride, non-specific fluorescence could be excluded.