INVOLVEMENT OF EPIDERMAL GROWTH-FACTOR IN INDUCING OBESITY IN OVARIECTOMIZED MICE

Ovariectomy (Ovx) of mice significantly increases the epidermal growth factor (EGF) concentration in the submandibular gland. To elucidate t he role of this elevated EGF in obesity of Ovx mice, we examined the e ffects of sialoadenectomy (Sx) and anti-EGF rabbit antiserum administr ation on the body weight (BW) gain and carcass fat deposition in Ovx a nimals. Studies were performed in four groups of mice consisting of co ntrol, Ovx, Ovx+Sx, and Ovx+anti-EGF groups. Ovx increased the BW gain compared with the control animals, whereas Sx and anti-EGF significan tly reduced it. Although the relative weights (weight ratio to BW) of the liver and kidney were not significantly changed by Ovx, Sx, or ant i-EGF treatment of Ovx mice, the relative weights of mesenteric, param etrial, and subcutaneous fat tissues were increased in Ovx mice, and t his increase was significantly reduced by Sx or anti-EGF administratio n. Ovx induced adipocyte hypertrophy, and this effect was eliminated b y Sx and anti-EGF. Moreover, acyl-CoA synthetase mRNA level was increa sed by Ovx, and this increase was reduced by Sx and anti-EGF in mesent eric fat tissue. These findings suggest that elevation of EGF may play a role in the induction of obesity in Ovx mice.