Changes in monoaminergic activity in the anterior, medium and posterior hypothalamus, gonadotropins levels and ovarian hormones during puberty of thefemale rat

The aim of present study is the analysis of monoamines concentrations chang es in the anterior, medium and posterior hypothalamus, as well as changes i n serum gonadotropins levels, ovarian steroids and follicular growth during the prepubertal development of the female rat. Noradrenergic activity in t he anterior, medium and posterior hypothalamus reached highest level at day 13 after birth, followed by a subsequent decrease from day 15 to 19 and an increase on days 22 and 27 postnatal. At day i, neural activity in the med ium hypothalamus was higher than the activity in the anterior and posterior hypothalamus. Serotoninergic activity in three portions of the hypothalamu s was higher throughout the prepubertal development. Follicle-stimulating h ormone and luteinizing hormone serum levels increased between days 11 and 1 7 and decreased from day 19 to 36. The concentration of 17 beta -estradiol was consistently low throughout the prepubertal development and increased a t day 39 after birth. These results indicate that during the prepubertal de velopment of the rat, the three regions of the hypothalamus show significan t changes in the monoaminergic neural activity. There is an inverse relatio nship between the noradrenergic activity on the anterior and medium hypotha lamus and serotoninergic activity in the posterior hypothalamus with ovaria n steroids during sexual maturation. These changes may be linked to the dev elopment of the neuroendocrine processes that modulate gonadotropin secreti on and ovarian function. (C) 2001 Elsevier Science Inc.