Effects of neurochemical lesions of the preoptic area on male sexual behavior in the Japanese quail.

Two experiments were carried out during which the noradrenergic neurotoxin, 5-amino-2,4-dihydroxy-alpha-methylphenylethylamine (5-ADMP) was applied to the brain of quail in order to evaluate the role of the noradrenergic system in the control of male copulatory behavior. In the first experiment, the ICV injection of 5-ADMP slightly enhanced the sexual behavior observed in testosterone (T)-treated castrated male quail. This brings additional support to the notion that norepinephrine tonically inhibits male copulatory behavior in quail. In the second experiment, 5-ADMP implanted directly into the preoptic area disrupted the restoration by T of copulatory behavior in castrated quail and, at the same time, produced a brain lesion that partly destroyed the sexually dimorphic medial preoptic nucleus, a previously established site of T action on behavior. These lesions produced by a high (presumably too high) concentration of neurotoxin provided an independent confirmation of effects previously observed after electrolytic lesions. Correlation analyses also confirmed that the medial part of the POM just rostral to the anterior commissure is more closely associated with copulatory behavior and may, therefore, represent a key center for steroid action on this behavior.