Expression of adropin in the reproductive organs of healthy female dogs and those with cystic endometrial hyperplasia, pyometra, and ovarian cysts

Adropin, a peptide encoded by the energy homeostasis-associated gene (ENHO), is expressed in multiple tissues. It regulates glucose and lipid metabolism, as well as immune responses and exerts anti-inflammatory effects in various diseases. It was found that adropin may also modulate the female reproductive system. The objective of this study was to determine the expression of Enho and adropin production in the canine ovary (in healthy individuals and those with ovarian cysts) and in the endometrium of healthy female dogs and those affected by cystic endometrial hyperplasia (CEH) and pyometra. The analyses used in the study included RT-qPCR, Western blot, and immunofluorescent assays. Moreover, concentration of adropin was detected by ELISA assay in plasma samples. The results demonstrated higher Enho expression and adropin production in healthy animals compared to female dogs suffering from pyometra disease. The results also showed elevated adropin production and its blood concentrations in CEH-affected bitches. In ovarian tissues, higher peptide expression was shown in animals with healthy gonads and coexisting uterus disorders (such as CEH or pyometra). In cases of ovarian cysts, significantly lower expression of both Enho mRNA and adropin production compared to healthy ovarian tissues was detected. The presented studies expand our knowledge of adropin expression and localization in canine reproductive organs during physiological and pathological conditions.