DISTINCT NEUROTROPHIC RESPONSES OF AXOTOMIZED MOTOR-NEURONS TO BDNF AND CNTF IN ADULT-RATS

IN adult mammals, transection of the hypoglossal nerve results in a dr amatic loss of choline acetyltransferase (ChAT) in the hypoglossal mot or neurons without affecting their cell number. This injury-induced re duction in ChAT is prevented when brain-derived neurotrophic factor (B DNF) is applied to the proximal end of the transected nerve. In contra st, application of ciliary neurotrophic factor (CNTF) has no such effe ct, even though both factors are known to rescue developing motor neur ons from cell death. These results suggest that BDNF may regulate the phenotypic expression of ChAT in mature motor neurons, and indicate th at the sensitivity and response of motor neurons to such neurotrophic agents change with development.