Recovery of function after brain damage: severe and chronic disruption by diazepam.
Following unilateral damage to the anterior-medial region of the neocortex (AMC) in rats a sensory asymmetry appeared, but recovered within a week. In a separate group of rats with AMC lesions daily 3-week exposure to diazepam (Valium, 5 mg/kg) beginning 12 h after surgery caused recovery to be delayed indefinitely. The efficiency and speed (as opposed to symmetry) of behavior was not impaired. More than 9 weeks after discontinuation of diazepam (12 weeks postsurgery), recovery was still not apparent. Postmortem analysis ruled out lesion size as a contributing factor. In a second experiment undrugged animals with AMC lesions were allowed to recover for at least 3 weeks before being exposed to diazepam. These animals showed only a transient (2-day) reinstatement of asymmetry despite continuous drug treatment. We conclude that important mechanisms serving recovery of function may be vulnerable during a short period soon after brain damage.
D000818:Animals; D001930:Brain Injuries / Q000503:physiopathology*; D003975:Diazepam / Q000633:toxicity*; D007839:Functional Laterality / Q000502:physiology; D008297:Male; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000187:drug effects*; D009475:Neurons, Afferent / Q000187:drug effects / Q000473:pathology; D011184:Postoperative Period; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D013003:Somatosensory Cortex / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology
D003975:Diazepam