Distribution of Ob-R and its mRNA has been examined in several species, including the mouse, rat, monkey, and human. The Ob-R has been found at all points along the HPG axis. Several groups have documented evidence of Ob-R mRNA in the gonads of mice, rats, and humans. Leptin has been shown to regulate expression of mRNAs for side chain cleavage enzyme and 17a-hydroxylase and to modulate LH-stimulated estradiol production in the ovary, providing evidence of functional Ob-R in these tissues. buy cheap antibiotics
The anterior pituitary is also a source of Ob-R mRNA although currently, the phenotype(s) of pituitary cells expressing Ob-R mRNA has not been identified. Yu et al. demonstrated that leptin stimulates gonadotropin release from rat pituitaries in vitro, indicating the ability of leptin to have a direct effect on pituitary tissue. Although evidence for leptin’s ability to modulate HPG activity at either the gonads or pituitary exists and should not be discounted, the remainder of the discussion on this topic will concentrate on possible mechanisms of leptin action within the central nervous system, focusing on the hypothalamus.