Authors : Y.Matsumoto , C.W. O`Gorman , E. Gonzales , D.H. Keisler , R.L. Stanko and M.R. Garcia
Abstract: The effect of development, stage of the estrous cycle and estradiol on adipocyte leptin, ER and ER gene expression was examined. Blood was collected twice weekly from 24 gilts before and after 1st estrus and analyzed for serum leptin by RIA. Serum concentrations of leptin increased (p = 0.02) to puberty. Subcutaneous adipose tissue was collected from 12 prepubertal (PP) gilts (121�1.2 d of age, 50.4�1.5 kg) and 12 Pubertal (PE) gilts (235�2.6 d of age, 137�3.3 kg) at first estrus (D 0) and during their mid-luteal (ML; D 8) stage of the respective estrous cycle for tissue mRNA analyses and cell culture. Isolated adipocytes were cultured for 18 h with 17 -estradiol (0, 10-11, 10-10, 10-9, 10-8, 10-7 M; n=3 wells/dose/pig). Leptin, ER , ER and cyclophilin mRNA were analyzed using real-time reverse transcription-polymerase chain reaction (RT-PCR). Leptin mRNA was found to be in greater abundance (p = 0.05) in adipose tissue from PE than PP or ML gilts. Estrogen receptor subtype gene expression was similar in adipose tissue from PP and PE gilts; however, ER tended (p<0.1) to be higher in adipose tissue from PE than ML gilts. In vitro studies revealed that 17 -estradiol had no effect on leptin gene expression in PP, PE, or ML adipocytes. Estrogen receptor gene expression decreased (p<0.05) in in vitro estradiol-treated PP and ML adipocytes; however, ER only decreased in estradiol-treated adipocytes from ML gilts. Estradiol did not appear to affect leptin, ER , or ER gene expression in PE adipocytes. Although the synthesis and secretion of leptin increased as puberty approached and appeared to change during the estrous cycle, these data do not attribute the developmental and / or reproductive cycle changes in leptin synthesis and secretion to a direct effect of estradiol.
Y.Matsumoto , C.W. O`Gorman , E. Gonzales , D.H. Keisler , R.L. Stanko and M.R. Garcia , 2006. Effects of Development, the Estrous Cycle and 17 -Estradiol on Adipocyte Leptin, Er and Er Gene Expression in Gilts. Journal of Animal and Veterinary Advances, 5: 762-770.