Erectile function in male rats after lesions in the lateral paragigantocellular nucleus

In previous research on rats, lesions of the lateral paragigantocellular nu cleus (LPGi) in the medulla have facilitated the display of reflexive erect ion and ejaculation. The present research sought to replicate and extend th ese findings by determining whether LPGi lesions would also promote erectio n during copulation and during exposure of the male to inaccessible females , i.e. noncontact erections (NCEs). As expected, males with LPGi lesions (n = 10) had a greater incidence of reflexive erection than males with sham l esions (n = 8), and during copulation LPGi-damaged males required fewer int romissions before ejaculation. However, the lesions did not change the copu latory intromission ratio, a partial measure of erectile function, nor did they change the incidence, latency, or number of NCEs displayed. More direc t measures of erection will be necessary to determine whether the inhibitor y role of LPGi on sexual reflexes is absent in some erectile contexts, or w hether its role in some contexts is too small to be evident in behavioral m easures. (C) 1999 Elsevier Science ireland Ltd. All rights reserved.