Olfactory bulbectomy counteracts inhibitory effect of food restriction on reproductive function

Previous studies have shown that bilateral removal of the olfactory bulbs (BX) results in a large increase in gonadotropin secretion in golden hamsters. The principal question addressed by the present study was whether BX would offset the inhibitory effect of food restriction on reproductive function. BX or sham (SH) BX male golden hamsters were fed ad libitum or were restricted to only enough food to maintain them at 70% of the body weight of control groups fed ad libitum. The SH-70% group underwent marked testicular regression after approximately 6-8 wk, but the testes size of the BX-70% hamsters decreased only in proportion to the decrease in body weight. The BX food-restricted group had to be fed more food to maintain the same weight as the SH-70% hamsters, and the BX-70% group also had a higher core body temperature, lower percent body fat, and higher serum free thyroxine levels than SH food-restricted animals. In summary, removal of the olfactory bulbs appears to facilitate tonic gonadotropin secretion, such that food restriction is no longer capable of inducing testicular regression. In addition, the olfactory bulbs may have a strong influence on metabolic function in golden hamsters.