Amphetamine-induced anorexia: Analysis with hypothalamic lesions and knife cuts

The present study examined the hypotheses that the midlateral perifornical region of the hypothalamus (PFH), at the level of the ventromedial nucleus, plays a crucial role in amphetamine (AMPH)-induced anorexia and that mediating fibers ascending to this brain region follow a midlateral course through the caudal hypothalamus. Electrolytic lesions that destroyed the PFH region attenuated the feeding suppression induced by intraperitoneal administration of AMPH. Lesions placed anterior, dorsal, or medial to this region, in contrast, did not decrease AMPH's effect. The medially-placed paraventricular nucleus lesion, in fact, enhanced drug response. Midlateral coronal wire-knife cuts in the caudal hypothalamus also attenuated AMPH anorexia. The crucial midlateral caudal hypothalamic cut also disrupted anorexia induced by direct injection of AMPH into the PFH area. The results obtained from the lesion data support the hypothesis that the PFH region is essential to AMPH's suppressive effect upon feeding, and the KC data suggest that crucial catecholamine fibers mediating this drug response ascend specifically through the midlateral portion of the hypothalamus.