Effect of kainic acid on unit discharge in CA1 area of hippocampal slice of DBA and C57 mice.

Spontaneous unit discharges in stratum pyramidale of CA1 area of hippocampal slices from DBA and C57 mice at different ages were recorded extracellularly. The average rate and amplitude of the spontaneous discharges from CA1 area of hippocampal slices bathed in artificial cerebrospinal fluid (aCSF) were not different between DBA and C57 mice at either 3-4 or 5-6 weeks of age. Bath application of kainic acid (KA) in concentrations of 0.5-1.0 microM produced different responses in CA1 area from these two strains of mice. In DBA mice at age 3-4 weeks, when they are most susceptible to audiogenic seizures, KA perfusion induced high-frequency repetitive single spikes and bursts of multiple population spikes in CA1 area. Very high-frequency discharges (10-fold higher than most responses) were also observed in 20% of all slices. In audiogenic seizure resistant C57 mice at age 3-4 weeks, KA perfusion at the same doses induced only the repetitive single spikes. The rate of spontaneous discharges was much lower than that in DBA mice. No burst of multiple population spikes nor very high-frequency responses were recorded in C57 mice. At age 5-6 weeks, when both DBA and C57 mice are resistant to audiogenic seizures, the rate of spontaneous discharges recorded from the CA1 area during and after KA perfusion was lower than that at age 3-4 weeks, and there was no significant difference between DBA and C57 mice.(ABSTRACT TRUNCATED AT 250 WORDS)