Neuronal signals regulate neurotrophin expression in oligodendrocytes of the basal forebrain

Previous studies suggest that oligodendrocytes express trophic molecules, including neurotrophins. These molecules have been shown to influence nearby neurons. To determine whether neuronal signals may, in turn, affect oligodendrocyte-derived trophins, we examined regulation of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) mRNA expression in cultured oligodendrocytes of the basal forebrain. Neuronal signals had distinct effects on individual neurotrophins. KCl elicited increases in BDNF mRNA, but did not affect expression of NGF or NT-3. The cholinergic agonist, carbachol, increased expression of NGF, but did not affect expression of BDNF or NT-3. Glutamate elicited a decrease in BDNF, but did not affect expression of NGF or NT-3. This glutamate effect is not due to toxicity, since the number of total cells was unchanged, while the number of mature myelin basic protein positive (MBP+) cells increased. Our observations suggest that individual neuronal signals distinctly influence the trophic function of oligodendrocytes.