The aim of this study was to demonstrate that POMC and the mu opioid receptor (MOR) were expressed in swine reproductive tract and swine spermatozoa. We found that the sow female reproductive tract expresses both POMC and MOR mRNA and MOR protein but, interestingly, the semen shows the highest expression level for both genes and also the highest MOR protein expression. The presence of POMC and MOR (opioid precursor/opioid receptor) transcripts suggests a local synthesis of opioids that could have paracrine and/or autocrine influences during some crucial points of reproduction such as fertilization and pregnancy.
Key words: opioid precursor, opioid receptor, reproduction, swin
