Effect of hypoxia/ischemia on bicuculline-induced seizures in immature rats: behavioral and electrocortical phenomena.
The relation between hypoxia/ischemia and subsequent alterations in seizure susceptibility in developing brain remains unclear. We assessed the behavioral and electrocorticographic (ECoG) effects of hypoxic/ischemic brain damage on bicuculline (BIC)-induced seizures in 7-day postnatal rats, and determined maturational changes in seizure susceptibility, behavior and ECoG activity. Rat pups were subjected to unilateral common carotid artery ligation, followed by exposure to 8% O2 at 37 degrees C for 2 h, an insult that produces brain damage in the cerebral hemisphere ipsilateral to carotid artery occlusion. The experimental group consisted of rat pups previously subjected to hypoxia/ischemia; control littermates received neither arterial ligation nor systemic hypoxia. Experimental animals received 4, 5, or 6 mg/kg BIC subcutaneously (s.c.) at 2 and 24 h, and at 3, 7, and 21 days of recovery from hypoxia/ischemia. Two animals at each interval of recovery, 1 each from the experimental and control groups, were used for ECoG monitoring. After BIC injection, animal behavior was observed for 2 h. Behaviors and seizures were classified in five categories based on severity, duration, and character: 1, mild irritability; 2, few clonic seizures and agitation; 3, few tonic-clonic seizures with swimming movements; 4, frequent tonic-clonic seizures with apneic episodes; 5, continuous tonic-clonic seizures and death. Rat pups previously subjected to hypoxia/ischemia had lesser seizure susceptibility than controls at 2-h recovery (p < 0.05) and greater susceptibility than controls at 24 h (p < 0.05). Tonic seizures were prominent at 2 and 24 h in both the experimental and control groups, whereas lesion-sided circling was prominent only in the hypoxic/ischemic rat pups.(ABSTRACT TRUNCATED AT 250 WORDS)
Cataltepe
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Department of Pathology (Neuropathology), Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey 17033, USA.
Barron
T F
TF
Heitjan
D F
DF
Vannucci
R C
RC
Towfighi
J
J
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001640:Bicuculline / Q000494:pharmacology*; D001921:Brain / Q000254:growth & development* / Q000503:physiopathology; D002545:Brain Ischemia / Q000503:physiopathology*; D004567:Electrodes, Implanted; D004569:Electroencephalography; D002534:Hypoxia, Brain / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced* / Q000503:physiopathology*
D001640:Bicuculline