Behavioural and neurochemical effects of chronic intraventricular injections of nerve growth factor in adult rats with fimbria lesions.

Rats received bilateral lesions of the fimbria. These lesions impaired their ability to learn a radial maze. Rats given repeated intraventricular injections of nerve growth factor (NGF, 10 micrograms twice weekly during 4 weeks after the lesion) learned the maze problem more rapidly than rats with the same injury but treated with a control protein (cytochrome c). When retested after a period of 6 weeks without NGF treatment, the performance of NGF-treated and cytochrome c-treated rats with fimbria lesions did not differ. Whereas our previous study showed an increase in choline acetyltransferase (ChAT) activity in the septum and the hippocampus 4 days after the last NGF injection, the present study found that after the retest period (i.e. 10 weeks after the last NGF injection) ChAT activity was increased in the septum but not in the hippocampus. The relationship between the NGF-induced changes in ChAT activity and behaviour is discussed.