Seasonal obesity in Syrian hamsters: effects of age, diet, photoperiod, and melatonin.


Two experiments examined the effects of photoperiod, melatonin, and diet on body weight in female Syrian hamsters (Mesocricetus auratus). In experiment 1, daily injections of 25 micrograms melatonin increased body weight when given 3 h before lights-out but not when given at the midpoint of the light phase, in a 16-h light-8-h dark cycle (LD 16:8). Ten… (More)