Involvement of the 5-HT1A and 5-HT1B serotonergic receptor subtypes in sexual arousal in male mice

The presence of a sexually receptive female behind a partition that prevents physical contact, but not seeing or smelling, increases blood testosterone level and induces the specific behavior in CBA male mice so that they more frequently approach the partition and spend more time near it in an attempt to make their way to the female. Treatment with the selective 5-HTIA scrotonin receptor agonist 8-OH-DPAT (0.1, 0.25, 0.5 and 2.0 mg/kg) induced a dose-dependent decrease in the amount of time spent by the males near the partition, or "partition time", which is considered the main pattern of sexual motivation. The activating effect of female exposure on the male's pituitary-testicular system was totally blocked, as no increase in plasma testosterone level was observed. The 5-HTIA antagonist p-MPPI (0.1, 0.2 and 0.4 mg/kg) itself did not affect behavior or alter plasma testosterone, but attenuated the inhibiting effect of S-OH-DPAT on behavior and totally antagonised the effect of the 5-HT1A agonist on testosterone response. The 5-HT1B agonist CGS-12066A (1.0 and 2.0 mg/kg) has no influence on the plasma testosterone increase exhibited by the male in response to female exposure. At the same time, either dose of CGS-12066A significantly reduced the partition time. The conclusion was made that the 5-HTIA subtype is involved in controlling both behavioral and hormonal indices of sexual arousal in male mice, while the 5-HT1B receptors antagonise sexual motivation, but do not modify the hypothalalamic-pituitary-testicular response. (C) 2002 Elsevier Science Ltd. All rights reserved.