Differential regional and time course increases in thyrotropin-releasing hormone, neuropeptide Y and enkephalin mRNAs following an amygdala kindled seizure.
Previous studies have shown that neuropeptide mRNA expression is altered in the dentate gyrus, and pyriform, entorhinal and perirhinal cortices following amygdala kindling. However, because rats were kindled every day and some mRNA alterations last longer than 24 h, a true measure of the alterations induced by a single seizure was confounded by the previous day's seizure. To circumvent this problem, rats were fully kindled, had six days without stimulation, and then were given one more seizure. Rats were sacrificed either 4 h, 24 h or 4 days after this last seizure. The levels of mRNAs for TRH, NPY and ENK were measured in the dentate gyrus and limbic cortices. Four hours after a seizure, TRH and NPY mRNAs were maximally increased in the dentate gyrus granule layer, but returned to baseline levels by 24 h. In contrast, 4 h after a seizure, TRH and NPY mRNAs were not, or only slightly, increased in the pyriform, entorhinal and perirhinal cortices, but significantly elevated 24 h after a seizure. ENK mRNA was increased both 4 and 24 h after a seizure in the pyriform, entorhinal and perirhinal cortices but showed no increases in the dentate gyrus at any time. By 4 days, peptide mRNA levels returned to baseline, except for ENK mRNA in the pyriform cortex. These results demonstrate a non-uniform and complex pattern of peptide mRNA expression following an amygdala kindled seizure. They further suggest that regional and time course differences in gene transcription and expression may be important factors in understanding both the transient, adaptive anticonvulsant and longer lasting proconvulsant effects of these neuropeptides.
Rosen
J B
JB
Biological Psychiatry Branch, National Institute of Mental Health, Bethesda, MD 20892.
Kim
S Y
SY
Post
R M
RM
D000679:Amygdala / Q000503:physiopathology*; D000818:Animals; D001483:Base Sequence; D004745:Enkephalins / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D007696:Kindling, Neurologic; D008297:Male; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009478:Neuropeptide Y / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors
D004745:Enkephalins; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D012333:RNA, Messenger; D013973:Thyrotropin-Releasing Hormone