Orchiectomy increases food intake and perifornical orexin A neuron's activity during glucoprivation

Abstract

We examined the effect of orchiectomy on food intake and lateral hypothalamic neuron fs activity during glucoprivation induced by i.v. 2‐deoxy‐D‐glucose (2DG) administration in male rats. Rats (7W) were bilaterally orchiectomized (OrX) or sham‐operated (Sham). 2DG (400 mg/kg) was infused two weeks after the operation and food intake was measured for 3 hours after the injection. The same experiment was performed for immunohistochemical examination of c‐Fos and orexin A expression in the perifornical area (PFA) and arcuate nucleus (Arc). Glucoprivation induced food intake, and food intake in OrX rats was larger than Sham rats, and food intake was inversely correlated with plasma testosterone concentration. Glucoprivation stimulated c‐Fos expression in the orexin A neurons at the PFA, and c‐Fos expression in the Arc. The number and fraction of c‐Fos expressed orexin A neurons was significantly higher in OrX rats than Sham rats. The number of c‐Fos ir cells in the Arc was also higher in OrX rats than Sham rats. These data indicate that testosterone attenuates food intake induced by reduced glucose availability via attenuated perifornical orexin A neuron's activity and Arc neuron's activity.