An ontogenic study of focal seizure induced by penicillin injection into sensorimotor area in rats.
The ontogenic development of focal seizure activity induced by penicillin injection into the unilateral sensorimotor area of rats was investigated in neonate, young, and weaning-through-adulthood groups. In the neonate group, the latency to the onset of repetitive isolated discharges (RIDs) was the longest. RIDs appeared in other structures simultaneously with the focus sensorimotor area, but their amplitude remained low compared to that in the focus. In the young group, RIDs and sustained high frequency discharges (SHDs) occurred. The latency to onset of RIDs was the shortest. RIDs propagated into subcortical structures more quickly than in the weaning-through-adulthood group, but their amplitude remained low in other structures. SHDs of high amplitude occurred in the ipsilateral subcortical structures simultaneously with those in the focus. In the weaning-through-adulthood group, the onset of SHDs was shorter and the frequency of SHDs was greater than those in the young group. RIDs and SHDs appeared in the focus sensorimotor area first and propagated to the ipsilateral caudate putamen, the medial nucleus of the thalamus, and the contralateral sensorimotor area at the early stage of seizures. Thereafter they propagated to other cortical and subcortical structures. These results suggest the following. A well-developed neocortex is needed for generation of SHDs as opposed to RIDs. In the young group, the ipsilateral subcortical structures play an important role in the generation of focal motor seizure. Following maturation, the bilateral sensorimotor areas, ipsilateral caudate putamen, and ipsilateral medial nucleus of the thalamus seem to increase in importance in producing the focal motor seizures.
Kudo
T
T
Department of Psychiatry and Neurology, Hokkaido University School of Medicine, Japan.
Yamauchi
T
T
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology; D004569:Electroencephalography; D004594:Electrophysiology; D007267:Injections; D009044:Motor Cortex / Q000254:growth & development / Q000502:physiology*; D010406:Penicillins / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time; D012640:Seizures / Q000139:chemically induced*; D013003:Somatosensory Cortex / Q000254:growth & development / Q000502:physiology*
D010406:Penicillins