Abstract

HERRERA GUTIERREZ, Héctor et al. Genetic expression associated to cell cycle, apoptosis, synaptogenesis and cell differentiation during sex differentiation in rats. Rev. mex. de cienc. pecuarias [online]. 2013, vol.4, n.3, pp.289-304. ISSN 2448-6698.

Important anatomical-functional differences are found between hypothalamus of male and female rats which appear and are regulated by sexual steroids during the critical hypothalamic development period. This is especially true of estradiol's involvement. In this study, several genetic differences between male and female rats were assessed. These differences are related to gene expression to apoptosis, neurogenesis and synaptogenesis in four-hour old rats. The effect of early administration of testosterone propionate (TP) to female rats, and tamoxifen (Tx) to male rats on the gene pattern expression was reviewed using dNa microarray analysis combined with qPRC. Gene expression differences were found in female and male hypothalamus. In female rats, there was greater gene expression related to apoptosis: IL-24, Smpd3, Tpa, Pp4, Map3k1, Pge and Naca3; to cell differentiation, Neurod2, Zicl and Epo; and to synapsis and the control of the cell cycle, Syt7, Tgfbr1, Ptf1a and Cox2. It was also shown that administration of Tx to male rats caused similar genetic expression to that of female rats, while TP given to female rats was not as effective in modifying gene expression. These results clearly show that in the absence of estradiol in female rats, genes favoring cell death are expressed which may explain size differences in certain hypothalamic areas in male and female rats. This may be due too to the fact that in male hypothalamus, certain areas are provided with greater estradiol alpha type receptors and therefore with manifest neuroprotection and other areas with beta receptors where apoptosis predominates.

Keywords : Hypothalamic sexual differentiation; Microarrays; Gene expression; Apoptosis; Cell differentiation.