Long-term alterations in growth factor mRNA expression following seizures

Although alterations in growth factor mRNA occur during neuronal insults, little is known about the long-term effects of neuronal insults on growth factor expression. We have examined the effects of prolonged post-ictal times on the expression of Brain-derivered nerve factor (BDNF) and Neurotrophin 3 (NT3) following Kainic acid (KA)-induced seizures. In situ hybridization was performed on male Sprague-Dawley rats sacrificed 1-2 weeks following intracranial ventricular KA injections. BDNF mRNA increased bilaterally 1 and 2 weeks after injections, whereas NT3 mRNA decreased contralaterally 1 week and bilaterally 2 weeks post-injection. These observations provide evidence that alterations in growth factor mRNA expression occur even after prolonged post-ictal recovery suggesting a possible role for growth factors in recovery and continued maintenance of surviving neurons within limbic seizure foci.