A CRITICAL PERIOD IN THE SENSITIVITY OF BASAL FOREBRAIN CHOLINERGIC NEURONS TO NGF DEPRIVATION

CHOLINERGIC neurones of basal forebrain (BF) express receptors for ner ve growth factor (NGF) and are sensitive to NGF. In many CNS structure s, including the BF region, the expression of NGF and its receptors is developmentally regulated. To test whether BF neurones depend on NGF during restricted time windows of postnatal development, we antagonize d endogenous NGF by implanting, in the lateral ventricle of the rat, h ybridoma cells producing blocking antibodies specific for NGF. Implant s were performed at postnatal day 2 (P2), P8 and P15. BF cholinergic n eurones were drastically reduced in number only when endogenous NGF wa s antagonized during the first postnatal week. We conclude that BF cho linergic neurones are sensitive to NGF deprivation only during early p ostnatal development.