Acupuncture to the Skin Induces Release of Substance P and Calcitonin Gene-Related Peptide From Peripheral Terminals of Primary Sensory Neurons in the Rat

We immunohistochemically examined the short term effects of electro-acupuncture (E-acupuncture) to the skin on substance P (SP)- and calcitonin gene-related peptide (CGRP) containing primary sensory neurons in the rat. Immunoreactivity to SP and CGRP in these neurons at the treatment site decreased after 30 min of E-acupuncture. These results suggest that E-acupuncture induces release of SP and CGRP from peripheral terminals of primary sensory neurons.