Enhanced visuospatial memory following intracerebroventricular administration of nerve growth factor

The present work assessed the effects of intracerebroventricular injections of rh recombined human nerve growth factor (rh NGF) (5 mu g/2.5 mu l) at p ostnatal days 12 and 13 upon the development of spatial learning capacities . The treated rats were trained at the age of 22 days to escape onto an inv isible platform at a fixed position in space in a Morris navigation task. F or half of the subjects, the training position was also cued, a procedure a imed at facilitating escape and at reducing attention to the distant spatia l cues. Later, at the age of 6 months, all the rats were trained in a radia l-arm maze task. Treatment effects were found in both immature and adult ra ts. The injection of NGF improved the performance in the Morris navigation task in both training conditions. There was a significant reduction in the escape latency and an increased bias toward the training platform quadrant during probe trials. The most consistent effect was the precocious developm ent of an adult-like spatial memory. In the radial-arm maze, the NGF-treate d rats made significantly fewer reentries than vehicle rats and this effect was particularly marked in the treated female rats. Taken together, these experiments reveal that the development and the maintenance of an accurate spatial representation are tightly related to the development of brain stru ctures facilitated by the action of NGF. Moreover, these experiments demons trate that an acute pharmacological treatment that leads to a transient mod ification in the choline acetyltransferase activity can induce a behavioral change long after the treatment. (C) 2000 Academic Press.