Acetylcholine release at motor neuron synapses has been long established; however, recent discoveries indicate that synaptic transmission by motor neurons is more complex than previously thought. Using whole-cell patch clamp, we show that spontaneous excitatory postsynaptic currents of rat motor neurons in primary ventral horn cultures are entirely glutamatergic, although the cells respond to exogenous acetylcholine. Motor neurons in cultures express the vesicular glutamate transporter VGlut2, and culturing motor neurons for weeks with glutamate receptors blocked upregulates glutamate signaling without increasing cholinergic signaling. In spinal cord slices, motor neurons showed no decrease in spontaneous excitatory synaptic potentials after blocking acetylcholine receptors. Our results suggest that motor neuron synapses formed on other neurons are largely glutamatergic in culture and the spinal cord.
aDepartment of Biological Sciences, Delaware State University, Dover
bDepartment of Biological Sciences, University of Delaware, Newark
cAlfred I. DuPont Hospital for Children, Wilmington, Delaware
dMD Anderson Texas Medical Center, Unit 0110, Houston, Texas, USA
Correspondence to Melissa A. Harrington, PhD, Department of Biological Sciences, Delaware State University, 1200 North Dupont Highway, Dover, DE 19901, USA Tel: +1 302 857 7117; fax: +1 302 857 6512; e-mail: firstname.lastname@example.org
Received July 21, 2011
Accepted July 25, 2011