Restraint accentuates the effects of 5-HT2 receptor antagonists and a 5-HT1A receptor agonist on lordosis behavior

Lynda Uphouse, Stacy White, Lance Harrison, Cindy Hiegel, Devi Majumdar, Jutatip Guptarak, William A. Truitt

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


The effect of restraint on lordosis behavior was examined in proestrous and ovariectomized, hormone-primed rats. Restraint durations from 5 to 60 min had no effect on lordosis behavior of proestrous rats. There was also no effect of 5 min restraint on lordosis behavior of ovariectomized rats hormonally primed with 10 μg estradiol benzoate and 500 μg progesterone. However, after intraperitoneal treatment with 1.0 mg/kg ketanserin tartrate (ketanserin), 5 min of restraint significantly reduced lordosis behavior of both groups of rats. The 5-min restraint combined with 0.50 or 0.75 mg/kg ketanserin reduced lordosis to mount (L/M) ratios of ovariectomized rats, while L/M ratios of proestrous rats were inhibited only by the 1.0 mg/kg dose. Increasing the restraint duration (10 or 15 min) reduced the dose of ketanserin necessary to reduce the L/M ratios of proestrous rats. Treatment with the selective serotonin (5-HT)2C receptor antagonist, SB206553 (2.5 or 5.0 mg/kg), in combination with 5 min of restraint, also reduced L/M ratios of hormonally primed, ovariectomized rats. The neural sites responsible for ketanserin's additivity with restraint are unknown, but infusion of the drug into the ventromedial nucleus of the hypothalamus (VMN) did not mimic the systemic treatment. However, 5 min of restraint did enhance the effects of VMN infusion with the 5-HT1A receptor agonist, 8-OH-DPAT. In contrast, 8-OH-DPAT's systemic potency was not enhanced by restraint. These findings support the hypothesis that a mild stressor increases the lordosis-inhibiting effects of 5-HT1A receptor agonists and that 5-HT2 receptors may protect against such disruption of lordosis behavior.

Original languageEnglish (US)
Pages (from-to)63-73
Number of pages11
JournalPharmacology Biochemistry and Behavior
Issue number1
StatePublished - Aug 2003
Externally publishedYes


  • Female rats
  • Ovariectomized rats
  • Serotonin
  • Sexual receptivity
  • Stress

ASJC Scopus subject areas

  • Biochemistry
  • Toxicology
  • Pharmacology
  • Clinical Biochemistry
  • Biological Psychiatry
  • Behavioral Neuroscience


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