A possible neurotransmitter role for CGRP in a hair-cell sensory organ.

We report that calcitonin gene-related peptide (CGRP) increases the discharge rate of afferent fibers innervating hair cells in the lateral line organ of Xenopus laevis. We have localized CGRP-like immunoreactivity in small, presumably efferent, fibers innervating the lateral line organ. In addition to providing evidence for a neurotransmitter role for CGRP in a sensory system, these results may help explain the non-cholinergic excitatory effect seen with efferent stimulation in this and other hair cell organs such as the inner ear.