The 5HT7 receptor subtype is involved in the regulation of female sexual behaviour in the rat

5-Hydroxytryptamine (5-HT) regulates sexual behaviour in the female rat via a number of its receptors. The role of the 5HT7 receptor was investigated in ovariectomised rats primed with 10 μg oestradiol benzoate (OB) followed at 48 h by 0.5 mg progesterone, which induced receptivity in approximately half of the animals. These animals were treated with three agonists all effective at 5HT1A and 5HT7 receptors; 5-hydroxytryptophan, 8-hydroxy-2-(di-n-propylamino)tetralin 1-Br (8-OH DPAT) and 5-carboxy-aminotryptamine (5-CT) in the presence or absence of selective 5HT1A and 5HT7 antagonists: WAY 100135 and SB 269970-A. The three agonists inhibited lordosis in the receptive group, and this was prevented by both the selective 5HT1A and 5HT7 antagonists. When given alone, both WAY 100135 and SB 269970-A increased the lordosis in the non-receptive rats indicating that endogenous 5-HT acting on 5HT1A and 5HT7 receptors may have a tonic inhibitory effect on receptivity. A comparison of OB priming doses on the effect of serotoninergic agents showed that the higher OB doses attenuated the inhibitory effect of 8-OH DPAT and enhanced the stimulatory effect of WAY 100135, but did not affect the actions of 5-CT or SB 269970-A. The interaction between oestradiol and 5-HT activity on sexual behaviour may therefore be selective to the 5HT1A pathway.