Opioid peptides decrease calcium-dependent action potential duration of mouse dorsal root ganglion neurons in cell culture.

We investigated opioid peptide actions on somatic calcium-dependent action potentials of dorsal root ganglion (DRG) neurons grown in primary dissociated cell culture. We report that leucine-enkephalin decreased the duration and amplitude of DRG somatic calcium-dependent action potentials. The opioid peptide action was dose-dependent over 20 nM to 5 microM and was antagonized by naloxone, consistent with mediation by opiate receptors. Thus, DRG neuron membranes have opiate receptors which act to decrease calcium influx. It is more likely, therefore, that opiate receptors on the somata of DRG neurons in culture are functionally similar to opiate receptors on primary afferent terminals.