THE EFFECT OF POSTINJURY KINDLED SEIZURES ON COGNITIVE PERFORMANCE OFTRAUMATICALLY BRAIN-INJURED RATS

The purpose of this experiment was to examine the consequences of post injury seizures on cognitive performance after experimental traumatic brain injury (TBI). Rats either were injured at a moderate (2.1 atm) l evel of central fluid percussion TBI (n = 16) or were surgically prepa red but did not receive a fluid pulse (sham-injured control, n = 16). Beginning 24 h after TBI, injured animals were injected (ip) once dail y (Days 1-24 postinjury) with either saline (n = 8) or 25 mg/kg pentyl enetetrazol (PTZ) (n = 8). Sham-injured rats were injected with an equ al volume of saline (n = 8) or PTZ (n = 8). In both injured and sham i njured animals, daily injections of PTZ resulted in an increase in the severity of behavioral seizures over days. On Days 25-29 after injury or sham injury, all animals were tested in the Morris water maze (MWM ). Analysis of maze performance indicated that in sham injured animals PTZ-produced seizures had a detrimental effect on performance. In inj ured animals, however, PTZ-treated animals exhibited significantly fas ter acquisition and better terminal performance in the MWM than did un treated injured animals. These results show that posttraumatic kindled seizures do not exacerbate behavioral deficits after TBI and may, in fact, improve recovery following injury. The findings of this experime nt are consistent with the hypothesis that post-TBI neuronal depressio n may contribute to behavioral morbidity following injury. (C) 1995 Ac ademic Press, Inc.