Lesions in medial preoptic area and bed nucleus of stria terminalis: differential effects on copulatory behavior and noncontact erection in male rats.

The goal of these studies was to assess the regulatory roles of the medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BST) in sexual arousal, inferred from noncontact erection (NCE) evoked in male rats by remote cues from estrous females. NCE and copulatory behavior were recorded before and after quinolinic acid or radiofrequency (RF) lesions were made in the MPOA (Experiments 1-3) or RF lesions were made in the BST (Experiment 4). All males with MPOA lesions, particularly in the rostral region, displayed severe deficits in copulation but little or no decrement in NCE. In contrast, BST lesions caused relatively moderate deficits in copulation, but they severely impaired NCE. Animals with larger BST lesions, including rostral and caudal medial regions, had more deficits in both copulatory behavior and NCE than did males with smaller lesions confined to the rostral medial BST. These results suggest that (1) the MPOA is critical for copulatory behavior but not for NCE, (2) males that stop copulating after MPOA lesions are still sexually aroused by estrous females, and (3) the BST plays an important role in mediating NCE.