Effects of the 5‐HT 2B receptor agonist, BW 723C86, on three rat models of anxiety

1 BW 723C86 (3 and 10 mg kg −1 , s.c. 30 min pretest), a 5‐HT 2B receptor agonist, increased total interaction, but not locomotion in a rat social interaction test, a profile consistent with anxiolysis. 2 The effect of BW 723C86 in the social interaction test is likely to be 5‐HT 2B 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 pretest) which did not affect basal levels of social interaction at the doses used. 3 An anxiolytic‐like action was also observed in the rat Geller‐Seifter conflict test, where BW 723C86 (0.5–50 mg kg −1 , s.c. 30 min pretest) modestly, but significantly increased punished, but not unpublished responding. 4 In a rat 5 min elevated x‐maze test, BW 723C86 (1–10 mg kg −1 , s.c.) had no significant effect. 5 The maximal anxiolytic‐like effect of BW 723C86 approached that of the benzodiazepine anxiolytic, chloradiazepoxide (5 mg kg −1 , s.c. 30 min pretest) in the social interaction test, but was markedly less in the Geller‐Seifter test. The effect of BW 723C86 was also clearly less than chlordiazepoxide in the elevated x‐maze procedure where it had no significant effect. 6 In conclusion, BW 723C86 exerted an appreciable anxiolytic‐like profile in a rat social interaction test, but had a weaker effect in the Geller‐Siefter and was ineffective in the elevated x‐maze test used. These effects are likely to be 5‐HT 2B receptor‐mediated.