The intake of β-sitosterol partially counteracts metformin beneficial effects in diet-induced obese rats

Despite the high coexistence of hyperlipidaemia and the prediabetes state, little is known about the effects of the beta-sitosterol and metformin (MET) combination. This study aimed to evaluate the effects of low doses of MET (75 or 150 mg/kg bw; M75 or M150) on western-diet induced obese (WDIO) rats, in combination or not with beta-sitosterol (176 mg/kg bw; SIT and N-SIT, respectively). The gains of body weight and body fat mass, calorie food intake and plasma leptin were reduced in M150 animals, both SIT and N-SIT groups. Only N-SIT animals showed that insulin levels and HOMA-IR were reduced in the M150 group. M150 group showed a tendency towards lower mRNA levels of Npy and increased Lepr mRNA levels in hypothalamus, but only in N-SIT animals. In conclusion, these results show that the co-administration of MET with beta-sitosterol seems to neutralise part of the beneficial effects of MET in WDIO rats.