Gender and gonadectomy influence specific proteins in the cerebellar cortex of the adult rat: a two-dimensional gel electrophoretic analysis

Sex differences in the brain expression of steroidogenic molecules under basal conditions and after gonadectomy

The brain is a steroidogenic tissue. It expresses key molecules involved in the synthesis and metabolism of neuroactive steroids, such as steroidogenic acute regulatory protein (StAR), translocator protein 18 kDa (TSPO), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), 3β-hydroxysteroid dehydrogenases (3β-HSD), 5α-reductases (5α-R) and 3α-hydroxysteroid oxidoreductases (3α-HSOR). Previous studies have shown that the levels of brain steroids are different in male and female rats under basal conditions and after gonadectomy. In the present study, we assessed gene expression of key neurosteroidogenic molecules in the cerebral cortex and cerebellum of gonadally intact and gonadectomised adult male and female rats. In the cerebellum, the basal mRNA levels of StAR and 3α-HSOR were significantly higher in females than in males. By contrast, the mRNA levels of TSPO and 5α-R were significantly higher in males. In the cerebral cortex, all neurosteroidogenic molecules analysed showed similar mRNA levels in males and females. Gonadectomy increased the expression of 5α-R in the brain of both sexes, although it affected the brain expression of StAR, TSPO, P450scc and 3α-HSOR in females only and with regional differences. Although protein levels were not investigated in the present study, our findings indicate that mRNA expression of steroidogenic molecules in the adult rat brain is sexually dimorphic and presents regional specificity, both under basal conditions and after gonadectomy. Thus, local steroidogenesis may contribute to the reported sex and regional differences in the levels of brain neuroactive steroids and may be involved in the generation of sex differences in the adult brain function.

Long-term effects of neonatal ovariectomy on cerebellar development in the rat: a histological and morphometric study

The effects of neonatal ovariectomy on cerebellar development and morphology were investigated in rats ovariectomized (OV) or sham-ovariectomized (SOV) 24 h after birth. At age 70 days rats were sacrificed and the cerebella processed for quantitative light microscopy of matched midline sagittal sections of the vermis. Body, brain and cerebellar weights, as well as total cerebellar area and area of the internal granular layer were significantly greater in the OV rats. The concentration (cells/mm2) and content (cells/section) of granule cells were significantly greater in each of the 10 vermal lobules of OV rats. The number of Purkinje (P) cells in the OV rats was significantly greater than control values for 6 lobules (L-III, L-V, L-VIb,c, L-VII, L-IX and L-X). P cell number for L-I, L-II and L-VIII was also higher in the OV group, but not significantly. The between group variation for P cell packing density (cells/mm) was significantly different, i.e. packing density for the OV rats was greater than the SOV value. The most consistent and significant difference between the folial patterns of SOV and OV groups was observed in L-VIII, the pyramis. A bilobed L-VIII occurred in 61.11% of SOV rats, but only in 16.67% of OV rats. Overall, neonatal ovariectomy significantly reduced the number of folia. Although the mechanisms are speculative, these data clearly indicate removal of the ovaries 24 h after birth, either directly and/or indirectly has long-term effects on cerebellar development.