Neuronal lesions in mercaptopropionic acid-induced status epilepticus.

Neuropathological studies of rats were made after seizures of different durations. Seizures were produced by mercaptopropionic acid in paralyzed, ventilated rats that were perfusion-fixed immediately (acute) or after 2-7 days of recovery (chronic). Analysis of chronic rats, which had only 20-min seizures, showed that damage occurred to several structures including: the substantia nigra pars reticulata, the hypothalamus, the diagonal band of Broca, and the globus pallidus; the damage was worse with longer seizures. In rats perfused acutely no changes were detected in paraffin sections in the aforementioned structures if the length of seizures was 45 min or less. It was concluded that: (1) mercaptopropionic acid-induced seizures cause permanent lesions to specific brain areas, with the most pronounced effect in the substantia nigra pars reticulata; (2) the lesions result from the seizures, and they are roughly proportional to the seizures duration; and (3) permanent lesions may begin within 20 min but require longer times to become visible on light microscopy.