Physiology & behavior
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Physiology & behavior · Feb 2002
Dissociation of the effects of nucleus raphe obscurus or rostral ventrolateral medulla lesions on eliminatory and sexual reflexes.
Rat preparations were used to investigate long-term changes in external anal sphincter (EAS) contractions and reflexive penile erection following electrolytic lesions of the nucleus raphe obscurus (nRO) or the rostral ventrolateral medulla. EAS contractions were measured electromyographically (EAS EMG) following distention of the EAS with a 5-mm probe. Penile erections were measured using a standard ex copula reflex testing paradigm. ⋯ Similar facilitation of erection latency was observed at 14 days postlesion, while erection number and flip total were no longer significantly different from controls. These and previous studies suggest that the nRO regulates defecatory reflexes in the rat. These data further suggest that the comingled EAS and bulbospongiosus (BS) motoneurons are controlled by discrete and separate brainstem circuits and that increases in EAS and penile reflexes after spinal cord lesions are mediated by loss of different descending inputs.