Concordant with its proposed role in relaying information about nutritional status, leptin has also been implicated in triggering the onset of puberty. Food restriction delays pubertal onset, and refeeding reverses this delay. We studied time of vaginal opening (VO) and first estrus in rats that were either 1) saline-treated and ad lib-fed, 2) leptin-treated and ad lib-fed, or 3) saline-treated and pair-fed to the leptin-treated group. We found that leptin treatment (6.3 ^g/g BW i.p. twice daily, starting on postnatal Day 23) caused animals to consume 80% of the amount of food eaten by ad lib-fed controls. buy cipro
Despite retarded growth due to food restriction, leptin-treated animals showed no differences in either the age of VO or first estrus compared to ad lib-fed animals, whereas at postnatal Day 38, none of the pair-fed animals had achieved either of these milestones. Ovarian and uterine weights corroborated these results, with pair-fed animals having underdeveloped ovaries and uteri compared to both ad lib-fed and leptin-treated rats. Interestingly, leptin treatment did not completely reverse the impact of a more severe food restriction (70% of ad lib-feeding) on the timing of pubertal onset in the same study.