Comparing the Seizure-Induced Impairment of Short-Term Plasticity in Dorsal and Ventral Hippocampus in Kindled Mice

There are many differences among dorsal and ventral hippocampal neural circuits that affect the synaptic plasticity. In this study we compared the occurrence of short-term plasticity in the field excitatory post synaptic potentials (fEPSP) in dorsal and ventral hippocampal CA1 area following kindled seizures. Animals (male C57 B6/J mice, 12 weeks of age) were kindled by intraperitoneal injections of pentylenetetrazole (PTZ) and fEPSPs were recorded from dorsal and ventral hippocampal slices. Short-term plasticity was evaluated by measuring fEPSP-slope and fEPSP-area following paired-pulse stimulation delivered at three inter-pulse intervals (20, 80 and 160 ms). Obtained results showed that in control slices fEPSP-slope was greater in ventral- compared to dorsal hippocampus, but there was no difference in fEPSP-area among two regions. In hippocampal slices of kindled animals, fEPSP-slope was similar in dorsal and ventral regions, but fEPSP-area was greater in ventral- compared to dorsal hippocampus. In addition, fEPSP-area was greater in kindled compared to control group only in ventral hippocampus. PTZ kindled slices showed impaired short-term facilitation and the paired-pulse index was reduced only at dorsal hippocampal slices. Kindling had no significant effect on paired-pulse ratio in ventral hippocampal slices. Our findings indicated that the seizure occurrence affected the neural activity of hippocampus in a regional dependent manner. Although kindling increased fEPSP-area in ventral hippocampus, kindling-induced changes in short-term synaptic plasticity was significant only in dorsal hippocampal slices compared to control group. The difference in the responses of hippocampal dorsal and ventral poles has to be considered in the future researches.