PENTYLENETETRAZOL SEIZURES INCREASE PRO-NERVE GROWTH FACTOR-LIKE IMMUNOREACTIVITY IN THE RETICULAR THALAMIC NUCLEUS AND NERVE GROWTH-FACTORMESSENGER-RNA IN THE DENTATE GYRUS

Neurotrophins may have a neuroprotective role and are probably involve d in the control of axonal sprouting and synaptic plasticity. An antib ody raised against a pro-sequence of nerve growth factor (NGF) was tes ted. In control undisturbed rats, a strong immunoreactivity was detect ed in scattered cells in and around the pyramidal and granule cell lay er of the hippocampus and a moderate labeling was found in the reticul ar thalamic nucleus. In situ hybridization showed specific expression of NGF mRNA in a similar population of scattered cells in the hippocam pal formation but not in the reticular thalamic nucleus. Acute epilept ic seizures, induced by a convulsive dose of 50 mg/kg pentylenetetrazo l (PTZ), strongly increased NGF mRNA in neurons of the granular layer of the dentate gyrus 3 hr but not 6 hr after the injection. No change in pro-NGF-like immunoreactivity was observed in the hippocampus or re ticular thalamic nucleus after acute seizures. Chemical kindling was i nduced by daily injections of subconvulsive doses (30 mg/kg) of PTZ fo r 4 weeks. This treatment significantly increased pro-NGF-like immunor eactivity in the reticular thalamic nucleus but did not affect NGF mRN A. These data strengthen a role for the reticular thalamic nucleus and NGF in PTZ kindling.