Concentrations of mRNAs encoding for preprosomatostatin and preprocholecystokinin are increased after kainic acid-induced seizures

Concentrations of preprosomatostatin-mRNA and preprocholecystokinin-mRNA were determined by Northern blot analysis in rats 2, 10, and 30 days after strong seizures induced by a single intraperitoneal injection of kainic acid. At all time intervals examined, levels of preprosomatostatin-mRNA were increased in the frontal cortex; so were levels of preprocholecystokinin-mRNA in the striatum. Transient increases, i.e., 2 days after kainic acid, of preprocholecystokinin-mRNA were observed in the frontal cortex and the substantia nigra. Preprocholecystokinin-mRNA was reduced in the hippocampus 2 and 10 days after kainic acid. Both preprosomatostatin- and preprocholecystokinin-mRNA levels showed a tendency to be reduced in the amygdala/pyriform cortex at all three time intervals. The increases in mRNA levels suggest enhanced rates of synthesis of the respective neuropeptides subsequent to kainic acid-induced seizures. They may also reflect a prolonged increase in the activity of the respective peptide-containing neurons. This is of special interest in the frontal cortex, since in this area both neuropeptides are found in interneurons and are widely colocalized with gamma-aminobutyric acid.