EFFECTS OF THE 5-HT2B RECEPTOR AGONIST, BW-723C86, ON 3 RAT MODELS OFANXIETY

1 BW 723C86 (3 and 10 mg kg(-1), s.c. 30 min pretest), a 5-HT2B recept or agonist, increased total interaction, but not locomotion in a rat s ocial interaction test, a profile consistent with anxiolysis. 2 The ef fect of BW 723C86 in the social interaction test is likely to be 5-HT2 B, receptor-mediated as it was prevented by pretreatment with the 5-HT 2C/2B receptor antagonist, SB 200646A. (1 and 2 mg kg(-1) p.o., 1 h pr etest) which did not affect basal levels of social interaction at the doses used. 3 An anxiolytic-like action was also observed in the rat G eller-Seifter conflict test, where BW 723C86 (0.5-50 mg kg(-1), s.c. 3 0 min pretest) modestly, but significantly increased punished, but not unpublished responding. 4 In a rat 5 min elevated x-maze test. BW 723 C86 (1-10 mg kg(-1), s.c.) had no significant effect. 5 The maximal an xiolytic-like effect of BW 723C86 approached that of the benzodiazepin e anxiolytic, chloradiazepoxide (5 mg kg(-1), s.c. 30 min pretest) in the social interaction test, but was markedly less in the Geller-Seift er test. The effect of BW 723C86 was also clearly less than chlordiaze poxide in the elevated x-maze procedure where it had no significant ef fect. 6 In conclusion, BW 723C86 exerted an appreciable anxiolytic-lik e profile in a rat social interaction test, bur had a weaker effect in the Geller-Siefter and was ineffective in the elevated x-maze test us ed. These effects are likely to be 5-HT2B receptor-mediated.