The neurobehavioral benefit conferred by a single systemic administration of 8-OH-DPAT after brain trauma is confined to a narrow therapeutic window

The 5-HT1A receptor agonist 8-OH-DPAT (0.5 mg/kg) enhances behavioral recovery when administered 15 min after experimental traumatic brain injury (TBI). To determine if benefits are still attainable at clinically relevant times, treatment was delayed 1 and 2 h post-TBI and motor/cognitive performance was compared to early (i.e., 15 min) administration. No differences were observed among the vehicle and 8-OH-DPAT groups treated at 1 and 2 h, but all three were significantly impaired versus early 8-OH-DPAT. The data suggest that an early and narrow critical period exists for the behavioral recovery afforded by a single 8-OH-DPAT treatment paradigm. The critical window corresponds to the well documented TBI-induced glutamate increase, suggesting that 8-OH-DPAT may be conferring neuroprotection by attenuating this acute deleterious surge.