Calcitonin gene-related peptide inhibits spontaneous contractions in human uterus and fallopian tube

The localization and effects of calcitonin gene-related peptide (CGRP) in the human uterus and fallopian tube were investigated. CGRP-immunoreactive nerve fibers were found in the muscular layers, around blood vessels and close to the epithelium. The oviduct and uterine cervix were more densely innervated than the corpus of the uterus. Substance P (SP)-like immunoreactivity was found in nerves with an overlapping distribution to that of CGRP-positive fibers. CGRP (2 × 10 10 to 10 7 M) dose-dependently and reversibly inhibited spontaneous contractions of uterine and oviductal strips, as well as SP-induced contractions in the oviduct. A role for CGRP-containing nerve fibers in regulation of motor activity in human female reproductive organs is suggested.