Estrogen receptor and POMC colocalization in the hypothalamus during sexual behavior and maternal aggression in female rats

Abstract

The study of neural basis of behavior allowed us to clarify the importance of the hypothalamus on the neural circuits involved in motivated behavior. Among motivated behaviors, sexual behavior and maternal aggression in females are organized in the same hypothalamic region, which comprises the ventrolateral portion of the ventromedial and the tuberal nucleus (VMHvl/TU). Also, these two behaviors are strongly influenced by sexual hormones, like estrogen. Previous studies showed that pro-opiomelanocortin (POMC) is expressed on the VMHvl/TU region, but its relationship with the organization of sexual behavior and maternal aggression is unclear. Furthermore, like estrogen receptor expression, POMC levels change according to the hormonal situation, as observed during different estrous cycle phases and lactation. During estrous, characterized by high estrogen concentrations and sexual receptivity towards a male, it was possible to observe high levels of POMC mRNA (through fluorescence in situ hybridization). Lactating rats otherwise, with low POMC mRNA levels, expressed maternal aggression towards the male intruder. This project looks forward to clarifying a possible neuronal colocalization in the expression of POMC and estrogen receptor on the VMHvl/TU nucleus, during the sexual behavior and maternal aggression. For this purpose, we will make a double immunoreaction for estrogen receptors and POMC and observe VMHvl/TU region in females in 4 different experimental groups.