Oestradiol and genistein reduce food intake in male and female overweight cats after gonadectomy

AIM: To determine if exogenous oestradiol or the phyto-oestrogen genistein could reduce food intake in male and female cats fed ad libitum that had been allowed to accrue excessive bodyfat following neutering. METHODS: Sixteen adult (eight female, eight male) cats were neutered and allowed to increase their bodyweight (BW) through feeding ad libitum of a complete and balanced dry diet. Oestradiol was injected subcutaneously for 5-day periods in incremental doses (0.25-4 microg per cat), then food intake was recorded, and vaginal cytological changes were observed in females. Similarly, genistein was administered orally for 5-day periods in incremental doses (5-100 mg/kg). RESULTS: In males and females, both oestradiol (p<0.001) and genistein (p=0.037) significantly reduced food intake during treatment, and the minimum daily doses that produced a significant effect were 0.5 mug and 100 mg/kg, respectively. The minimum daily dose of oestradiol that produced a significant effect on food intake was not associated with changes in vaginal cytology over the 5-day treatment period. CONCLUSIONS AND CLINICAL RELEVANCE: Gonadal oestradiol appeared to be a key modulator of food intake in both male and female cats, and replacement of oestrogen to neutered cats via oestradiol or an oestrogen surrogate such as genistein has potential for reducing the prevalence of obesity in neutered cats.