Chronic, post-injury administration of D-cycloserine, an NMDA partial agonist, enhances cognitive performance following experimental brain injury.

The purpose of this study was to determine the effect of augmenting NMDA receptor activation on cognitive deficits produced by traumatic brain injury (TBI). Specifically, D-cycloserine (DCS), a partial agonist of the NMDA-associated glycine site, was tested as a potential cognitive enhancer. Rats were injured using lateral fluid percussion TBI (2.8 +/- .10 atm). On days 1-15 post-injury, animals were injected (i.p.) with vehicle (n = 8), 10 mg/kg (n = 9), or 30 mg/kg (n = 8) of DCS. Sham-injured animals treated with either vehicle (n = 8) or 30 mg/kg of DCS (n = 8) were used for comparison. On days 11-15 post-injury, cognitive function was assessed using the Morris water maze (MWM). Results indicate that the 30 mg/kg dose of DCS significantly attenuated memory deficits as compared to injured vehicle-treated animals (P < 0.01). Analysis also revealed that performance of the injured-DCS (30 mg/kg) group was not significantly different from sham-injured animals treated with vehicle (P > 0.10). In contrast, the 10 mg/kg dose of DCS was ineffective in reducing injury-induced memory deficits. DCS (30 mg/kg) also significantly improved the spatial memory of sham-injured animals when compared with sham-injured animals treated with vehicle (P < 0.05). In conclusion, chronic, post-injury enhancement of the NMDA receptor is an effective strategy for ameliorating TBI-associated cognitive deficits.