RESUMEN
The participation of estrogens in depression has been well recognized. To exert its effects, estradiol binds mainly to estrogen receptors ESR1 and ESR2 (α and ß, respectively), expressed in brain regions including the hippocampus, limbic regions and hypothalamic nuclei. In rodents, modified estrogen receptors expression in brain areas have been implicated in different signs similar to those observed in depressive patients. Neonatal clomipramine (CMI) treatment is a pharmacological manipulation that generates behavioral and neurochemical changes that persist throughout adulthood and resemble human depression. The aim of this study was to analyze whether CMI neonatal treatment modifies the expression of nuclear ESR1 and ESR2 in the hippocampus, amygdala basolateral (BLA), amygdala medial (MeA), hypothalamic medial preoptic area (mPOA) and raphe nucleus in male rats. Our results indicate that CMI treatment significantly induced an mRNA increase of ESR1 in the hypothalamus, additionally produce a reduction in the mRNA ESR2 expression in raphe accompanied of an increase in hypothalamus and amygdala. CMI treated rats show more immunorreactive cells to ESR1 (ESR1-ir) in mPOA, BLA, MeA, together with a reduction of these cells in the hippocampal CA1 region. Moreover, an increase in the number of immunorreactive cells to ESR2 (ESR2-ir), in BLA and MeA, was observed in CMI treated rats. Additionally, the hippocampal CA2 region and raphe nucleus showed a decrease in these cells. Also, neonatal CMI treatment induced a decrease in the number of cells of the pyramidal layer in CA1. Overall, the results suggest that neonatal CMI treatment in rats (during brain development) induces changes in estrogen receptors in different brain areas involved with the regulation of depressive-like behaviors.