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

In previous research on rats, lesions of the lateral paragigantocellular nucleus (LPGi) in the medulla have facilitated the display of reflexive erection and ejaculation. The present research sought to replicate and extend these findings by determining whether LPGi lesions would also promote erection during copulation and during exposure of the male to inaccessible females, i.e. non-contact erections (NCEs). As expected, males with LPGi lesions (n = 10) had a greater incidence of reflexive erection than males with sham lesions (n = 8), and during copulation LPGi-damaged males required fewer intromissions before ejaculation. However, the lesions did not change the copulatory intromission ratio, a partial measure of erectile function, nor did they change the incidence, latency, or number of NCEs displayed. More direct measures of erection will be necessary to determine whether the inhibitory role of LPGi on sexual reflexes is absent in some erectile contexts, or whether its role in some contexts is too small to be evident in behavioral measures.