Nerve growth factor rapidly induces prolonged acetylcholine release from cultured basal forebrain neurons: differentiation between neuromodulatory and neurotrophic influences.
Long-term exposure to nerve growth factor (NGF) is well established to have neurotrophic effects on basal forebrain cholinergic neurons, but its potential actions as a fast-acting neuromodulator are not as well understood. We report that NGF (0.1-100 ng/ml) rapidly (<60 min) and robustly enhanced constitutive acetylcholine (ACh) release (148-384% of control) from basal forebrain cultures without immediate persistent increases in choline acetyltransferase activity. More ACh was released in response to NGF when exposure was coupled with a higher depolarization level, suggesting activity dependence. In a long-term potentiation-like manner, brief NGF exposure (10 ng/ml; 60 min) induced robust and prolonged increases in ACh release, a capacity that was shared with the other neurotrophins. K252a (10-100 nm), BAPTA-AM (25 microm), and Cd(2+) (200 microm) prevented NGF enhancement of ACh release, suggesting the involvement of TrkA receptors, Ca(2+), and voltage-gated Ca(2+) channels, respectively. Forskolin (10 microm), a cAMP generator, enhanced constitutive ACh release but did not interact synergistically with NGF. Tetrodotoxin (1 microm) and cycloheximide (2 microm) did not prevent NGF-induced ACh release, indicative of action at the level of the cholinergic nerve terminal and that new protein synthesis is not required for this neurotransmitter-like effect, respectively. In contrast, after a 24 hr NGF treatment, distinct protein synthesis-dependent and independent effects on choline acetyltransferase activity and ACh release were observed. These results indicate that neuromodulator/neurotransmitter-like (protein synthesis-independent) and neurotrophic (translation-dependent) actions likely make distinct contributions to the enhancement of cholinergic activity by NGF.
Auld
D S
DS
Douglas Hospital Research Center, Montréal, Québec, Canada H4H 1R3.
Mennicken
F
F
Quirion
R
R
D000109:Acetylcholine / Q000096:biosynthesis*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000187:drug effects; D020932:Nerve Growth Factor / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D016548:Prosencephalon / Q000166:cytology / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D020917:Receptor, trkA / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D015220:Calcium Channels; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D009414:Nerve Growth Factors; D018377:Neurotransmitter Agents; D011500:Protein Synthesis Inhibitors; D002104:Cadmium; D005576:Colforsin; D013779:Tetrodotoxin; D020932:Nerve Growth Factor; D002795:Choline O-Acetyltransferase; D020917:Receptor, trkA; D000109:Acetylcholine; D002118:Calcium