PreproVIP-derived peptides in the human female genital tract: expression and biological function

The aim of the study was to elucidate the localization, distribution, colocalization and biological effect of preproVIP-derived peptides in the human female genital tract. Radioimmunoassays applying antisera against the five functional domains of the VIP precursor in combination with immunohistochemistry were used. The effect of preproVIP 22-79, preproVIP 111-122 and preproVIP 156-170 on genital smooth muscle activity in the Fallopian tube was investigated in vitro and compared to that of VIP. All the preproVIP-derived peptides were expressed throughout the genital tract in neuronal elements closely related to the epithelial lining, perivascular tissue and non-vascular smooth muscle. Colocalization of the peptides was evidenced by double immunostaining. In contrast to VIP, preproVIP 22-79, preproVIP 111-122 and preproVIP 156-170 did not cause a significant inhibition of smooth muscle activity. The findings indicate that tissue-specific differences in post-translational processing of preproVIP exist in the female genital tract.