Mice Lacking α-Calcitonin Gene-Related Peptide Exhibit Normal Cardiovascular Regulation and Neuromuscular Development

Abstract

α-Calcitonin gene-related peptide (αCGRP) is a pleiotropic peptide neuromodulator that is widely expressed throughout the central and peripheral nervous systems. CGRP has been implicated in a variety of physiological processes including peripheral vasodilation, cardiac acceleration, nicotinic acetylcholine receptor (AChR) synthesis and function, testicular descent, nociception, carbohydrate metabolism, gastrointestinal motility, neurogenic inflammation, and gastric acid secretion. To provide a better understanding of the physiological role(s) mediated by this peptide neurotransmitter, we have generated αCGRP-null mice by targeted modification in embryonic stem cells. Mice lacking αCGRP expression demonstrate no obvious phenotypic differences from their wild-type littermates. Detailed analysis of systemic cardiovascular function revealed no differences between control and mutant mice regarding heart rate and blood pressure under basal or exercise-induced conditions and subsequent to pharmacological manipulation. Characterization of neuromuscular junction morphology including nicotinic receptor localization, terminal sprouting in response to denervation, developmental regulation of AChR subunit expression, and synapse elimination also revealed no differences in αCGRP-deficient animals. These results suggest that αCGRP is not required for the systemic regulation of cardiovascular hemodynamics or development of the neuromuscular junction.