[Melatonin action in apoptosis and vascular endothelial growth factor in adrenal cortex of pinealectomized female rats].

Purpose: to evaluate the reactivity of VEGF-A and cleaved caspase-3 in the adrenal gland cortex of female pinealectomized rats treated with melatonin.

Methods: forty adult female rats were divided into 4 groups (G) of 10 animals: GI - no surgical intervention, with vehicle administration; GII - sham pinealectomized with vehicle administration; GIII - pinealectomized with vehicle administration; GIV - pinealectomized with melatonin administration (10 µg/animal) during the night. After 60 days of treatment, all animals were anesthetized, and the adrenal glands were removed and fixed in 10% formaldehyde (phosphate buffered) for histological processing and paraffin embedding. Sections (5 µm thick) were collected on silanized slides and submitted to imunnohistochemical methods for the detection of cleaved caspase-3 (apoptosis) and of vascular endothelial growth factor (VEGF-A) in the adrenal cortex. The data obtained were submitted to analysis of variance (ANOVA) complemented by the Tukey-Kramer test (p≤0.05).

Results: reactivity to cleaved Caspase-3 was noted in the zona glomerulosa of the adrenal glands in all studied groups. There were no significant differences in the zona glomerulosa; however, the zona fasciculata (15.51±3.12*, p≤0.05) and the zona reticularis (8.11±1.90*, p≤0.05) presented the smallest percentage of apoptosis in the pinealectomized group (GIII). The reactivity to the VEGF-A was stronger in the zona glomerulosa and weaker in the zona reticularis in all groups. We found a stronger VEGF-A reactivity in the zona fasciculata in the pinealectomized group (GIII).

Conclusions: the pineal gland affects the arrangement of the zona glomerulosa and reticularis of the adrenal glands, which are related to the production of sex hormones.