Calcitonin gene related peptide and neuropeptide Y in skeletal muscle after eccentric exercise: a microdialysis study

Objectives: To detect neuropeptides in human skeletal muscle at rest and after eccentric exercise. Method: Eight healthy subjects participated in the study. Microdialysis of the distal part of the vastus lateralis of the quadriceps muscle and pain evaluation were performed immediately after eccentric exercise, after two days, and at rest. Calcitonin gene related peptide ( CGRP) and neuropeptide Y ( NPY), representatives of the sensory and autonomic nervous system, were analysed by radioimmunoassay. Results: Overall, the measured concentrations were low, some even below the limit of detection. At rest, CGRP was detected in two of seven samples, but after eccentric exercise it was detected in 27 of 30 samples. At rest, all NPY concentrations were below the limit of detection, but after exercise it was found in six of 30 samples. Conclusion: The significant increase in detectability of CGRP after eccentric exercise may be related to the increased experience of pain. Therefore the occurrence of CGRP after heavy eccentric exercise may be associated with the regulation of delayed onset muscle soreness and possibly also the stimulation of tissue regeneration.