Examination of persistent effects of repeated administration of pentylenetetrazol on rat hippocampal CA1: evidence from in vitro study on hippocampal slices.
The early and long-lasting effects of pentylenetetrazol-kindling on hippocampal CA1 synaptic transmission were investigated. Experiments were carried out in the hippocampal slices from control and kindled rats at two post-kindling periods, i.e. 48-144 h (early phase) and 30-33 days (long-lasting phase). Field potentials, i.e. population excitatory postsynaptic potential (pEPSP) and population spike (PS) were recorded at the stratum pyramidale following stimulation of the stratum radiatum. Kindling-induced changes in synaptic transmission were assessed by stimulus-response functions and paired-pulse responses. The results showed that 48-144 h after kindling, the PS amplitude in the CA1 of kindled slices enhanced, and a second PS appeared compared to control slices. But at 30-33 days after kindling, the pEPSP slope in the CA1 of kindled slices enhanced without any change in the PS compared with those in the control slices. Evaluation of paired-pulse responses showed a significant reduction in paired-pulse inhibition for PS 48-144 h after kindling and a significant increase in paired-pulse inhibition for pEPSP 30-33 days after kindling. Our results suggest that pentylenetetrazol-kindling is accompanied by enhanced excitability and a reduction of paired-pulse inhibition in hippocampal CA1. The increased paired-pulse inhibition one month after kindling, may be interpreted as an adaptive process to cope with subsequent seizures.
Fathollahi
Y
Y
Department of Physiology, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran.
Motamedi
F
F
Semnanian
S
S
Zardoshti
M
M
D000704:Analysis of Variance; D000818:Animals; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D007696:Kindling, Neurologic; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D010433:Pentylenetetrazole / Q000008:administration & dosage*; D017966:Pyramidal Cells / Q000187:drug effects*; D051381:Rats; D013997:Time Factors
D010433:Pentylenetetrazole