Phencyclidine-induced head-weaving and head-twitch through interaction with 5-HT1 and 5-HT2 receptors in reserpinized rats.

Phencyclidine mainly produced head-weaving and head-twitches at doses of 5-7.5 mg/kg and of 7.5-12.5 mg/kg, respectively. Phencyclidine-induced head-twitches and head-weaving were blocked by pretreatment with ritanserin (1 mg/kg), a selective serotonin (5-HT)2 receptor antagonist and with pindolol (20 mg/kg, s.c.), a 5-HT1 receptor antagonist, respectively. In reserpine-pretreated rats, the degree of utilization of 5-HT and the number of 5-HT1 ([3H]5-HT) and 5-HT2 ([3H]ketanserin) binding sites were significantly increased compared with the figures for the vehicle-pretreated rats. The intensity of phencyclidine-induced head-weaving (at the dose of 2.5 mg/kg) and head-twitch (at the doses of 2.5 and 5 mg/kg) was significantly increased in reserpine-pretreated rats compared with that of vehicle-pretreated rats. Furthermore, in the reserpine-pretreated rats, the intensity of phencyclidine (1.25 mg/kg)-induced head-weaving and head-twitches was increased in combination with imipramine, while the intensity of phencyclidine (2.5 mg/kg)-induced head-weaving and head-twitch was decreased by pretreatment with mianserin, a non-selective 5-HT receptor antagonist. These results indicate that phencyclidine induced head-weaving by interacting with 5-HT1 receptors, indirectly after the release of 5-HT and/or with some other mechanisms and induced head-twitch by interacting with 5-HT2 receptors directly and/or indirectly.