Stimulation of the hypothamus initiates the urethrogenital reflex in male rats

Lesley Marson*, Kevin E. McKenna

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


The urethrogenital (UG) reflex is a spinal sexual reflex which is tonically inhibited in the intact male rat by neurons in the nucleus paragigantocellularis (nPGi). The medial preoptic area of the hypothalamus (MPOA) is involved in the actication of male sexual behavior. The present study examines the effect of hypothalamic stimulation on the UG reflex in the intact male rat. Areas of the hypothalamus were stimulated bilaterally with either electrical stimulation or D,L-homocysteic acid (DLH) and the presence of the UG reflex examined. Stimulation of discrete areas of the hypothalamus evoked the UG reflex. The UG reflex could be initiated in the absence of genital stimulation. Microinjections of DLH into the MPOA also initiate the UG reflex. These data suggest that stimulation of neurons in the MPOA overcome the inhibition by the nPGi and facilitate spinal genital reflexes leading to ejaculation.

Original languageEnglish (US)
Pages (from-to)103-108
Number of pages6
JournalBrain research
Issue number1-2
StatePublished - Feb 28 1994


  • Ejaculation
  • Medial preoptic area
  • Sexual function

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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