Facilitation of mounting behavior in male rats by intracranial injections of luteinizing hormone-releasing hormone

Daniel M. Dorsa, Erla R. Smith

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Luteinizing hormone-releasing hormone (LH-RH) administration has been reported to facilitate male sex behavior. This laboratory has previously reported development of the ‘mounting test’, a paradigm which reflects sexual arousal mechanisms. We have used this test to study the interaction of LH-RH with the central components of male copulatory behavior in the rat. Sixty 90-day-old Long-Evans male rats were screened for sex behavior and divided into 5 treatment groups. For all mounting tests, a local anesthetic was applied to the penis and mounts were scored during a 15-min exposure to a stimulus female. The animals were given 3 successive weekly tests. By the final test, a significant decrement in mounting behavior was noted, and those males given 50 ng LH-RH i.c.v. displayed more mounting in this test than animals given either no treatment or saline (P < 0.01). A slight but significant (P < 0.05) enhancement of performance was also noted in peptide-treated rats in test I. There was no significant difference in any of the tests between animals given lateral cerebroventricular (i.c.v.) injections of 2 μl acidified saline and those given no treatment. When blood samples were taken from similarly treated animals and assayed by radioimmunoassay for luteinizing hormone and testosterone, plasma levels of these hormones were not different at either 30 min or 2 h after injection of saline or LH-RH. Thus, in animals with diminished genital sensory input, LH-RH administration increases mounting behavior without inducing measurable reproductive endocrine changes. It is proposed that this effect results from an interaction of this peptide with the neural substrates of the arousal mechanism.

Original languageEnglish (US)
Pages (from-to)147-155
Number of pages9
JournalRegulatory Peptides
Volume1
Issue number2
DOIs
StatePublished - Jan 1 1980

Keywords

  • CNS effects
  • arousal
  • endocrine effects
  • intracerebroventricular injection
  • neuropeptide
  • sex behavior

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Endocrinology
  • Clinical Biochemistry
  • Cellular and Molecular Neuroscience

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