What makes a sympathetic neuron cholinergic?
Brain-derived neurotrophic factor (BDNF) is part of the family of neurotrophins involved in neuronal development and function. Yang et al. used a cell culture model to study the effect of BDRF on the functional connections that exists between sympathetic neurons and cardiac myocytes. Short exposure (15 minutes) to BDNF lead to a rapid shift from excitatory noradrenergic to inhibitory cholinergic transmission in response to neuronal stimulation. Neurons lacking the p75 neurotrophin receptor did not release acetylcholine in response to BDNF, and neurons overexpressing p75 showed increased cholinergic transmission. These findings suggest that BDNF, acting through p75, induces the preferential release of acetylcholine in response to neuronal stimulation. During development, sympathetic neurons innervating rodent sweat glands undergo a targeted change in neurotransmitter phenotype from noradrenergic to cholinergic, even though neurons continue to express tyrosine hydroxylase (TH, the enzyme
