Abstract: In order to observe the expression and localization of brain derived neurotrophic factor (BDNF) mRNA in the rat brain following midbrain reticular formation(MRF) injury, MRF injury was produced by means of neurotoxin ibotenic acid(IA) injection into MRF. Synthetic oligonucleotide probed for BDNF mRNA was lebeled with digoxigenin(DIG). In situ hybridization was used to study expression and localization of BDNFmRNA in brain. In the hippocampal formation, strongly labeled neurons were found in and around the pyramidal layer, as well as in the granular layer and hilus of the dentate gyrus of the rats. Other neurons in these areas were more weakly labeled or unlabeled. High BDNFmRNA expression was also observed in scattered neurons in cortex cerebri, in many neurons in claustrum and in certain other areas. These results suggested that BDNF might act via a direct neuron to neuron interaction . The localization of BDNFmRNA expression in cortical areas and in claustrum suggested that the target neurons for this factor extended beyond the sensory ganglion and retinal ganglion cells. Finaily , BDNF mRNA expression in vivo in the central nervous system appeared to be mostly confined to neurons.

Key words: BDNFmRNA localization, midbrain injury, in situ hybridization