Chronic leptin infusion advances, and immunoneutralization of leptin postpones puberty onset in normally fed and feed restricted female rats

Does leptin play a vital role in initiating puberty in female rats and can it overrule a nutrionally imposed (i.e. a 30% feed restriction, FR) delay in puberty onset? Prepubertal female rats were chronically infused for 14 days with leptin (icv or sc) or leptin-antiserum (icv) while puberty onset was monitored by means of scoring the moment of vaginal opening (VO). Median VO age was higher (35 days versus 27 days) in FR animals but leptin levels at VO were significantly decreased (1.44 ± 0.17 ng/ml versus 2.79 ± 0.31 ng/ml). Centrally (icv) and peripherally (sc) infused leptin (1 ¿g/day) advanced VO age compared to FR controls (30 days versus 35 days and 31 days versus 41 days, respectively). Congruently, centrally (icv) administered leptin-antiserum (0.6 ¿g/day) delayed puberty onset. In normally fed rats median VO age was only marginally advanced (26 days versus 27 days) but only if leptin was applied centrally. The effects of FR on puberty onset are counteracted or even normalized by the infusion of leptin, whereas immunoneutralization of central leptin postpones puberty onset. We therefore conclude that central leptin is crucial for initiating puberty in female rats

Central Application of IGF-1 Postpones Time of Vaginal Opening in Normally Fed, but Not in Food-Restricted Rats

Background/Aims: Central but also peripheral IGF-1 is suggested to play a role in the initiation of puberty as it directly affects GnRH synthesis and release. A possible intermediate in the effects of IGF-1 on puberty might be the adiposity-signaling hormone leptin, whose plasma levels are decreased in food-restricted (FR) rats. Methods: IGF-1 was chronically centrally infused in 23-day-old prepubertal female rats which were either normally fed or 30% FR, and the effects on time of vaginal opening (VO) and plasma leptin levels were monitored. Results: FR treatment postponed time of VO and decreased plasma leptin levels. In normally fed rats centrally infused with IGF-1, time of VO was found to be postponed to the same extent as FR treatment did. The IGF-1 infusion did not affect plasma leptin levels in normally fed animals but increased leptin levels in the FR group compared to controls. Daily food intake was equal between all groups but body weight course was lower in FR rats. IGF-1 treatment did not significantly affect food intake or body weight course. Conclusion: FR treatment delays the moment of vaginal opening to the same extent as observed in normally fed rats that were centrally infused with IGF-1

Central Application of IGF-1 Postpones Time of Vaginal Opening in Normally Fed, but Not in Food-Restricted Rats

Background/Aims: Central but also peripheral IGF-1 is suggested to play a role in the initiation of puberty as it directly affects GnRH synthesis and release. A possible intermediate in the effects of IGF-1 on puberty might be the adiposity-signaling hormone leptin, whose plasma levels are decreased in food-restricted (FR) rats. Methods: IGF-1 was chronically centrally infused in 23-day-old prepubertal female rats which were either normally fed or 30% FR, and the effects on time of vaginal opening (VO) and plasma leptin levels were monitored. Results: FR treatment postponed time of VO and decreased plasma leptin levels. In normally fed rats centrally infused with IGF-1, time of VO was found to be postponed to the same extent as FR treatment did. The IGF-1 infusion did not affect plasma leptin levels in normally fed animals but increased leptin levels in the FR group compared to controls. Daily food intake was equal between all groups but body weight course was lower in FR rats. IGF-1 treatment did not significantly affect food intake or body weight course. Conclusion: FR treatment delays the moment of vaginal opening to the same extent as observed in normally fed rats that were centrally infused with IGF-1

Effects of central infusion and immunoneutralization of growth hormone on the timing of puberty and plasma leptin levels in the female rat

Growth hormone (GH) levels increase during puberty though its role in puberty onset is still unclear. An interaction is suggested between GH and leptin, as triggering factor of puberty. To evaluate the role of GH on the timing of puberty and its relation with leptin, we centrally administered recombinant human GH (rhGH; 1 ¿g/day) to normally fed or food-restricted (FR) prepubertal female rats, and monitored time of vaginal opening (VO). Median time of VO was equally postponed in FR animals and in normally fed rhGH-infused rats: median time of VO was respectively 35 and 34 vs. 27 d. Central infusion of rhGH in FR rats partially restored the delay in VO. Plasma leptin levels were increased in rhGH-infused animals, normally fed or FR. Centrally infused anti-rat GH (0.6 ¿g/day) did not affect plasma leptin levels, but advanced median time of VO (25 vs. 28 d) in pair-fed female rats but not in ad lib-fed animals. The effects of the centrally infused compounds appear to depend on the dietary regime imposed on the prepubertal animals. Furthermore, plasma leptin levels show no direct or predictive relation to the time of VO. The data indicate an involvement of GH in puberty onset, but do not explain the mechanism employed

Blood pressure in 12-year-old children is associated with Fatty Acid composition of human milk: the prevention and incidence of asthma and mite allergy birth cohort.

Breastfed individuals have a lower blood pressure than formula-fed individuals. Supplementation with n-3 long-chain polyunsaturated fatty acids in adults is also associated with a lower blood pressure. We studied whether children receiving human milk with a relatively high content of n-3 long-chain polyunsaturated fatty acids have a lower blood pressure at age 12 years, and, if so, whether this association is explained by the n-3 long-chain polyunsaturated fatty acids content in erythrocyte membranes at age 12 years. Within a 12-year follow-up of a population-based birth cohort, we compared blood pressure of 205 never-breastfed children and 109 children who had fatty acid composition of their mothers' breast milk measured during lactation. In addition, 973 children had information on erythrocyte fatty acid composition and blood pressure at age 12 years. Children who received human milk with an n-3 long-chain polyunsaturated fatty acids content above the median (ie, 0.51 weight percentage) had a 4.79-mm Hg lower systolic (95% CI, -7.64 to -1.94) and a 2.47-mm Hg lower diastolic (95% CI, -4.45 to -0.49) blood pressure at age 12 years than never-breastfed children. N-3 long-chain polyunsaturated fatty acids levels in human milk below the median value and current n-3 long-chain polyunsaturated fatty acid status were not associated with blood pressure at age 12 years. Thus, a relatively high content of n-3 long-chain polyunsaturated fatty acids in human milk is associated with a lower blood pressure in children at age 12 years, a finding not explained by current n-3 long-chain polyunsaturated fatty acids status