Dissociation of the effects of nucleus raphe obscurus or rostral ventrolateral medulla lesions on eliminatory and sexual reflexes

Gregory Holmes, G. E. Hermann, R. C. Rogers, J. C. Bresnahan, M. S. Beattie

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

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. At 48 h postlesion, 100% of nRO-lesioned animals displayed reflexive erections and the magnitude of EAS EMG was significantly greater in lesioned animals than in sham controls. These results suggested EAS hyperreflexia following destruction of the nRO. By 14 days postlesion, EAS responsiveness in nRO-lesioned animals had returned to levels comparable to nonlesioned animals. No measures of penile erection were affected by nRO lesions. In animals with nucleus gigantocellularis (Gi) and lateral nucleus paragigantocellularis (Gi-lPGi) lesions, no significant changes to EAS reflexes were observed at any time point. At 48 h postoperative, Gi-lPGi lesions significantly reduced the latency to first erection and increased the number of erections elicited relative to controls. 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.

Original languageEnglish (US)
Pages (from-to)49-55
Number of pages7
JournalPhysiology and Behavior
Volume75
Issue number1-2
DOIs
StatePublished - Feb 1 2002

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Anal Canal
Reflex
Penile Erection
Nucleus Raphe Obscurus
Abnormal Reflexes
Motor Neurons
Brain Stem
Spinal Cord

All Science Journal Classification (ASJC) codes

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience

Cite this

Holmes, Gregory ; Hermann, G. E. ; Rogers, R. C. ; Bresnahan, J. C. ; Beattie, M. S. / Dissociation of the effects of nucleus raphe obscurus or rostral ventrolateral medulla lesions on eliminatory and sexual reflexes. In: Physiology and Behavior. 2002 ; Vol. 75, No. 1-2. pp. 49-55.
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Dissociation of the effects of nucleus raphe obscurus or rostral ventrolateral medulla lesions on eliminatory and sexual reflexes. / Holmes, Gregory; Hermann, G. E.; Rogers, R. C.; Bresnahan, J. C.; Beattie, M. S.

In: Physiology and Behavior, Vol. 75, No. 1-2, 01.02.2002, p. 49-55.

Research output: Contribution to journalArticle

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