The potential role of periovarian fat and leptin in initiation of puberty in the immature rat

Twenty-four-day old female rats were injected with 25 mu g recombinant lept in twice daily for 24, 48, 72, or 93 h, Periovarian fat contained significa ntly greater amounts of aromatase mRNA at 72 and 93 h and estradiol at 72 h after leptin treatment as compared to the ovary. On the other hand, there was an increase in testosterone at 72 h and progesterone at 72 and 93 h aft er leptin in the ovary as compared to periovarian fat. Cholesterol side cha in cleavage and 17 alpha-hydroxylase mRNA were found only in the ovary and not periovarian fat. Thus, periovarian fat has a greater capacity to synthe size estrogen than the ovary in the immature rat and adipose tissue may ser ve as the primary source of estrogen in the prepubertal period which result s in the onset of puberty.