Departamento de Psicobiología, Universidad Nacional de Educación a Distancia (UNED), C/ Juan del Rosal n° 10, 28040 Madrid, Spain, Instituto Mixto de Investigación Escuela Nacional de Sanidad (IMIENS). Electronic address: [Email]
Estradiol not only participates in the regulation of energy metabolism in adulthood, but also during the first stages of life as it modulates the alterations induced by under- and over-nutrition. The objectives of the present study were to determine: 1) If estradiol is involved in the normal programming of energy metabolism in rats; 2) If there is a specific window of time for this programming and 3) If males and females are differentially vulnerable to the action of this hormone. Estrogen receptors (ER) α, ERβ and GPER were blocked by their specific antagonists MPP, PHTPP and G15, respectively, from postnatal day (P) 1 (the day of birth) to P5 or from P5 to P13. Physiological parameters such as body weight, fat depots and caloric intake were then analysed at P90. Hypothalamic AgRP, POMC, MC4R, ERα, ERβ and GPER mRNA levels and plasma levels of estradiol, were also studied. We found that blocking ER receptors from P5 to P13 significantly decreases long-term body weight in males and hypothalamic POMC mRNA levels in females. The blocking of ERs from P1 to P5 only affected plasma estradiol levels in females. The present results indicate programming actions of estradiol from P5 to P13 on body weight in male and POMC expression in female rats and emphasize the importance of including both sexes in metabolic studies. It is necessary to unravel the mechanisms that underlie the actions of estradiol on food intake, both during development and in adulthood, and to determine how this programming differentially takes place in males and females.