Low ambient temperature during early postnatal development fails to cause a permanent induction of brown adipocytes

摘要

The brown adipocyte phenotype (BAP) in white adipose tissue (WAT) is transiently induced in adult mammals in response to reduced ambient temperature. Since it is unknown whether a cold challenge can permanently induce brown adipocytes (BAs), we reared C57BL/6J (B6) and AxB8/PgJ (AxB8) mice at 17 or 29 degrees C from birth to weaning, to assess the BAP in young and adult mice. Energy balance measurements showed that 17 degrees C reduced fat mass in the preweaning mice by increasing energy expenditure and suppressed diet-induced obesity in adults. Microarray analysis of global gene expression of inguinal fat (ING) from 10-day-old (D) mice indicates that expression at 17 degrees C vs. 29 degrees C was not different. Between 10 and 21 days of age, the BAP was induced coincident with morphologic remodeling of ING and marked changes in expression of neural development genes (e.g., Akap 12 and Ngfr). Analyses of Ucp1 mRNA and protein showed that 17 degrees C transiently increased the BAP in ING from 21D mice; however, BAs were unexpectedly present in mice reared at 29 degrees C. The involution of the BAP in WAT occurred after weaning inmice reared at 23 degrees C. Therefore, the capacity to stimulate thermogenically competent BAs in WAT is set by a temperature-independent, genetically controlled program between birth and weaning.