Evaluation of PTZ kindling and lateral hypothalamus inactivation on kindling and hippocampal neuronal survival

Epilepsy, as a plastic change lead to hyperexcitability and structural change. Kindling is the process of repetitive subconvulsive electrical or chemical stimulation induced synaptic and circuit alterations. Lateral hypothalamus (LH) contains the main constellation of orexinergic neurons involved in sleep and waking and even excitability with high numbers of receptors in hippocampus. Thus, we investigate the effect of LH inactivation on kindling development and kindling induced hippocampal neuronal population.
Pentylenetetrazol (PTZ; 45 mg/kg) was used to induce chemical kindling every 48 h up to 13 injections, intraperitoneally. Three consecutive 4 or 5 seizure stages were criteria for kindling. Lidocaine (2%) was injected stereotaxically into right LH, 0.5 h prior to PTZ administration. Nissl staining was used to demonstrate neuronal population survival in CA3 and hilar regions of hippocampus.
LH inactivation prevented PTZ kindling development. Although kindling increased neuronal dispersion in CA3 and hilar regions, LH inactivation was unable to reduce the dispersion. Moreover, kindling did not affect neuronal survival in CA3 and hilus, qualitatively.
It is concluded that kindling induced structural changes is to some extent independent of kindling development and it is not prevented by kindling inhibition through LH inactivation.