Behavioral effects mediated by the modulatory glycine site of the NMDA receptor in the anterodorsal striatum and nucleus accumbens.

The striatum and the nucleus accumbens are the main input structures of the basal ganglia (BG). They contribute differently to motor behavior controlled by the BG in rats, e.g., stereo-typed behavior, catalepsy, and locomotion. Whereas the striatum is predominantly involved in the control of sniffing behavior and catalepsy, the nucleus accumbens contributes to control of locomotion. To test whether the allosteric glycine site of the NMDA receptor complex modulates these behavioral variables, we injected the glycine-site antagonist 7-chlorokynurenate and the glycine-site agonist D-serine into the anterodorsal striatum and the nucleus accumbens and studied their influence on stereotypical snout contacts and locomotion. Additionally, the effects of intrastriatal injections of 7-chlorokynurenate on haloperidol- and SCH 23390-induced catalepsy were investigated. 7-Chlorokynurenate enhanced stereotypical snout contacts in the anterodorsal striatum and in the nucleus accumbens but did not change spontaneous locomotion in either of these structures. Haloperidol- but not SCH 23390-induced catalepsy was attenuated by intrastriatally administered 7-chlorokynurenate. The glycine-site agonist D-serine had no effect on stereotypical snout contacts and locomotion. The results suggest that motor behavior mediated by the striatopallidal output pathway is modulated by the glycine site, whereas motor behavior mediated by the accumbopallidal and striatonigral output pathway is not.