Induction of c-fos mRNA expression by afterdischarge in the hippocampus of naive and kindled rats.
Periodic induction of focal electrical seizure [afterdischarge (AD)] is an absolute prerequisite for the development of kindling, an animal model of complex partial epilepsy. Once established, it is a permanent condition. The mechanism(s) that translate ADs, which last tens of seconds, into life-long alterations in the CNS is unclear. Cellular immediate-early genes have been implicated in the conversion of short-term stimuli to long-term alterations in cellular phenotypes by regulating target gene expression. We have investigated the contribution of one such early gene, c-fos, to this process. The relationship between ADs and expression of c-fos gene in the rat hippocampus, a key structure in kindling development, was studied by analysis of mRNA levels. The low constitutive expression of c-fos mRNA in the hippocampus was not altered by kindling. There was an "all-or-none" relationship between induction of c-fos and the duration of AD. The threshold for induction was approximately 30 s of AD. Above-threshold ADs induced c-fos in both naive and kindled animals to the same extent and with identical temporal profiles. Although the expression of c-fos is unchanged with kindling, c-fos may nonetheless contribute to many long-term changes of kindling, both adaptive and epileptogenic.
Shin
C
C
Department of Medicine (Neurology), Duke University Medical Center, Durham, North Carolina.
McNamara
J O
JO
Morgan
J I
JI
Curran
T
T
Cohen
D R
DR
D000818:Animals; D004569:Electroencephalography; D015870:Gene Expression; D006624:Hippocampus / Q000378:metabolism*; D007696:Kindling, Neurologic / Q000502:physiology*; D007700:Kinetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger