Twenty-four-hour leptin levels respond to cumulative short-term energy imbalance and predict subsequent intake.

Leptin plays a vital role in the regulation of energy balance in rodent models of obesity. However, less information is available about its homeostatic role in humans. The aim of this study was to determine whether leptin serves as an indicator of short-term energy balance by measuring acute effects of small manipulations in energy intake on leptin levels in normal individuals. The 12-day study was composed of four consecutive dietary-treatment periods of 3 days each. Baseline (BASE) [100% total energy expenditure (TEE)] feeding, followed by random crossover periods of overfeeding (130% TEE) or underfeeding (70% TEE) separated by a eucaloric (100% TEE) washout (WASH) period. The study participants were six healthy, nonobese subjects. Leptin levels serially measured throughout the study period allowed a daily profile for each treatment period to be constructed and a 24-h average to be calculated; ad libitum intake during breakfast "buffet" following each treatment period was also measured. Average changes in mesor leptin levels during WASH, which were sensitive to energy balance effected during the prior period, were observed. After underfeeding, leptin levels during WASH were 88 +/- 16% of those during BASE compared with 135 +/- 22% following overfeeding (P = 0.03). Leptin levels did not return to BASE during WASH when intake returned to 100% TEE, but instead were restored (104 +/- 21% and 106 +/- 16%; not significant) only after subjects crossed-over to complementary dietary treatment that restored cumulative energy balance. Changes in ad libitum intake from BASE correlated with changes in leptin levels (r2 = 0.40; P = 0.01). Leptin levels are acutely responsive to modest changes in energy balance. Because leptin levels returned to BASE only after completion of a complementary feeding period and restoration of cumulative energy balance, leptin levels reflect short-term cumulative energy balance. Leptin seems to maintain cumulative energy balance by modulating energy intake.

Pax-2: a developmental gene constitutively expressed in the mouse epididymis and ductus deferens.

PURPOSE: To characterize expression of the transcriptional activator, Pax-2, in the mouse lower genitourinary tract. MATERIALS AND METHODS: Expression of Pax-2 was studied by Northern analysis, ribonuclease protection and immunohistochemistry. RESULTS: Immunostaining revealed localized expression in the epithelium of the ductus deferens and epididymis at all time points from birth to adulthood. Expression in these structures in adult mice was confirmed by Northern analysis and ribonuclease protection assays. CONCLUSION: Pax-2 is a transcriptional regulator expressed in the epithelium of the ductus deferens and epididymis and may be a regulator of epithelial genes involved in sperm maturation and support.

Expression of the homeotic gene Hox-d13 in the developing and adult mouse prostate.

PURPOSE: To examine expression of the homeotic gene Hox-d13 in the developing mouse prostate. MATERIALS AND METHODS: Expression was assayed by Northern analysis, reverse-transcriptase polymerase chain reaction and in situ hybridization. RESULTS: Expression is present in the urogenital sinus in late gestation and is localized postnatally in the urethral epithelium and prostatic ducts. Expression continues throughout development and persists in the adult prostate. CONCLUSION: A restricted domain of Hox-d13 expression in the developing urogenital tract is consistent with the role of the Hox genes in specifying regional identity during development. Expression in the prostate postnatally suggests additional roles in prostate ductal morphogenesis and/or cell differentiation.