Effects of sildenafil treatment on thermogenesis and glucose homeostasis in diet-induced obese mice

a Eight days of sildenafil treatment induced a significant elevation of hepatic cGMP levels in DIO mice (P？=？0.0089). b However, body weight of control mice and mice treated with sildenafil was not affected by the treatment and c organ weights of iBAT, iWAT, eWAT, and liver (normalized to body weight) were similar. d Rectal body temperature was measured using a small-diameter thermocouple probe (accuracy: 0.1？°C) before (day 0) and during the sildenafil treatment (day 5). e–f In parallel, infrared thermography (sensitivity: 0.05？°C) of the iBAT area was performed on conscious animals and both were unchanged after 5 days of treatment. g–i In line, gene expression analysis in iBAT revealed no differences in expression of Ucp1, Pparγ, Fabp4, Cd36, Cd68, and Mcp-1, whereas in iWAT Pparγ (P？=？0.0233) and Fabp4 (P？=？0.0425) were significantly downregulated and Cd68 (P？=？0.0201) upregulated. Furthermore, Mcp-1 expression was significantly lower in eWAT after sildenafil treatment (P？=？0.0406). *P？<？0.05, **P？<？0.01, unpaired, two-tailed t-tests with Welch-correction (a, c, g–i). Repeated measures two-way ANOVA following Bonferroni’s multiple comparisons test (b, d–f). Data are presented as mean？±？s.e.m., n？=？8. Cd36 cluster of differentiation 36, Cd68 cluster of differentiation 68, cGMP cyclic guanosine monophosphate, eWAT epididymal white adipose tissue. Fabp4 fatty acid-binding protein 4, iBAT interscapular brown adipose tissue, iWAT inguinal white adipose tissue, Lep Leptin, Mcp-1 monocyte chemoattractant protein-1, Pparγ peroxisome proliferator-activated receptor gamma, Ucp1 uncoupling protein