D-CYCLOSERINE ENHANCES SOCIAL-BEHAVIOR IN INDIVIDUALLY-HOUSED MICE INTHE RESIDENT-INTRUDER TEST

D-Cycloserine (DCS) has been reported to affect the central nervous sy stem in man. To investigate whether the compound produces specific beh avioural effects, DCS was administered to male mice in a resident-intr uder situation and the behaviour of the interacting mice assessed usin g ethological analysis. Resident mice given DCS (32.0-320.0 mg/kg PO, 60 min before testing) showed dose-dependent increases in social inves tigation, smaller increases in sexual behaviour and decreased aggressi veness. Defensive and flight behaviour were not affected. Intruder mic e showed slight increases in sexual behaviour that were not dose-depen dent, and small increases in social investigation. The increases in so cial investigation induced by DCS (320.0 mg/kg) in resident mice were not reversible with R-HA 966 (32.0 mg/kg IP, 30 min before testing), a blocker of the strychnine-insensitive glycine modulatory site associa ted with the N-methyl-D-aspartate receptor, but were blocked by the GA BA antagonist bicuculline (0.56 mg/kg IP, 5 min before testing). The s mall DCS-induced increase in sexual behaviour in residents was reverse d by R-HA 966. Within the parameters of the resident-intruder situatio n, DCS exerts socio-sexual behaviour-enhancing effects which are depen dent upon the role of the interactant, and which are mediated by an ac tion upon multiple substrates. DCS may be regarded as another example of a sociotropic (approach-promoting) agent.