Figure 6. Altered BAT and sympathetic nerve activity (SNA) in perigonadal fat of females lacking SIRT1 in POMC neurons.

(A) Ucp1 and Pgc1α mRNA levels in interscapular brown adipose tissue (IBAT) of 28-week-old Sirt1^loxP/loxP and Pomc-Cre; Sirt1^loxP/loxP females fed on a high calorie (HC) diet for 20 weeks. (B) Ucp1 and Cidea mRNA levels in visceral (perigonadal, perirenal, mesenteric) and subcutaneous (inguinal and mammary) white adipose tissue (WAT) of same mice as in A (n=7–11). Individual mRNA levels were normalized to β-actin mRNA contents. (C) UCP1 and β-actin (used as loading control) protein levels were assessed in the perigonadal fat of same mice as in in A (UCP1/β-actin content is reduced in mutants; P=0.021; n=3–4) by western blot. (D) Representative photomicrographs of paraffin-embedded perigonadal WAT sections stained with hematoxylin and eosin (H&E) or treated for UCP1 immunohistochemistry (IHC). Tissues were collected from same mice as in A. Dark-brown staining represents UCP1-expressing brown adipocytes. Higher magnification of the boxed-region is in the top-right corner. Scale bar = 100 μm. (E) Quantification of SNA in perigonadal WAT of 12-week-old Sirt1^loxP/loxP and Pomc-Cre; Sirt1^loxP/loxP females fed on a HC diet for 4 weeks (n=8). (F) Body weights before and after one week of treatment with either placebo or the selective β3-adrenergic receptor agonist CL316,243 (n=15–16). Error bars represent s.e.m. Statistical analyses were done using two-tailed unpaired Student’s t test. ^† P=0.05; *P<0.05; **P<0.01; **P<0.001.