Danish Medical Bulletin - No. 2. June 2004. Vol. 51 Page 226.

ABSTRACT OF PhD DISSERTATION

5-HT2 receptors
and paced mating behaviour
in the female rat

Per Nedergaard, MSc

PDF

This PhD dissertation was accepted by the Faculty of Health Sciences, University of Copenhagen, and defended on May 14, 2004.

Official opponents: Knut Larsson, Josefa Vega-Matuszczyk, Sweden, and David D. P. Woldbye.

Tutor: Erling Mellerup.

Correspondence: Per Nedergaard, Gustav Adolfs Gade 14, 1., DK-2100 Copenhagen Ø. E-mail: per@nedergaard.org

Dan Med Bull 2004;51:226.

ABSTRACT

This work was carried out at the Laboratory for Neuropsychiatry, Copenhagen University Hospital, and Department of Pharmacology, University of Copenhagen.

Previous studies have demonstrated the importance of 5-HT 2A and 5-HT 2C receptors in the regulation of female rat sexual behaviour. In general, most studies on sexual motivation in the female rat have applied test conditions where the male paced the copulatory activity. However, recent studies indicate that only self-paced mating is rewarding to the female rat. The present work investigated the role of 5-HT 2A and 5-HT 2C receptors in regulation of sexual motivation in the female rat using a paced mating set-up in which the female has the possibility to escape from the male during copulation. This test situation more closely resembles naturalistic conditions than does the more often used male-paced models.

The results support the hypothesis that 5-HT 2A and 5-HT 2C receptors are important in the regulation of female rat sexual motivation. Stimulation of 5-HT 2A receptors with the in vivo 5-HT 2A receptor agonist, DOI, facilitated sexual motivation. This effect was attenuated by administration of nefazodone, which has in vivo 5-HT 2A receptor antagonist activity. In contrast, stimulation of 5-HT 2C receptors with the in vivo 5-HT 2C receptor agonist, MK-212, inhibited sexual motivation. This finding is in contrast to previous studies reporting facilitated lordosis behaviour following MK-212 treatment. The effects of MK-212 on paced mating behaviour were attenuated by olanzapine, which has in vivo 5-HT 2C and 5-HT 2A receptor antagonist activity.

Hence, the present work demonstrated the importance of appropriate test methods in the study of female rat sexual behaviour. Furthermore, the results indicate opposite functions of 5-HT 2A and 5-HT 2C receptors in the regulation of female rat sexual motivation.
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