TIME-DEPENDENT CHANGES IN NEUROTROPHIC FACTOR MESSENGER-RNA EXPRESSION AFTER KINDLING AND LONG-TERM POTENTIATION IN RATS

We compared the time-dependent changes in messenger ribonucleic acid ( mRNA) levels for two neurotrophic factors after amygdala-kindled seizu res and hippocampal longterm potentiation (LTP) in rats in vivo. The b rain-derived neurotrophic factor (BDNF) mRNA levels in the bilateral g ranule cell layer of the dentate gyrus, increased significantly 1-4 h after stage 5 kindled seizures. Nerve growth factor (NGF) mRNA levels increased throughout the bilateral limbic regions more gradually than those of BDNF mRNA. The maximum levels in the dentate gyrus ipsilatera l to stimulation (BDNF mRNA: 493%, NGF mRNA: 199% of control levels) o ccurred 2 h after seizures. As observed with kindling, BDNF and NGF mR NA expression increased in the dentate gyrus ipsilateral to stimulatio n also increased following LTP induced by the perforant path stimulati on, with maximum levels occurring 2 h and 4 h, respectively, after sti mulation, when they reached 284% and 189% of the control levels, respe ctively. These results suggest that BDNF and NGF are involved in enhan cement of synaptic efficacy in the granule cells of the dentate gyrus in the hippocampus in kindling, not related to the neuronal excitabili ty associated with seizure activity. (C) 1998 Elsevier Science Inc.