Adiponectin system in the skin of the obese dog: a comparative study

Introduction: Adipokines regulate skin functions under physiological and pathological conditions. Obesity influences on a plethora of associated diseases including skin dermatological disorders. However, adipokines are poorly investigated in the skin of obese animals. This work aims to study the localization and expression of adiponectin (ADIPOQ), and its related receptors (ADIPOR1 and ADIPOR2), in the skin comparing obese and normal-weight dogs. Materials and Methods: The study was carried out on of ten obese (body condition score, BCS ≥7/9) and ten normal-weight (BCS of 4–5/9) adult dogs. Skin biopsies were collected from the ventral region and used to perform Real-time PCR and immunohistochemistry. Results: ADIPOQ and ADIPOR2 immunostaining was observed in the sweat and sebaceous glands, in the adipose tissue extending among follicular clusters, in the endothelium and some connective cells. In addition, ADIPOR1 and ADIPOR2 were observed in the epidermis, in the hair follicles, in the sweat and sebaceous glands. Significant expression differences were observed for ADIPOQ and ADIPOR2 transcripts that were 5.4-fold (p<0.01) and 2.3-fold less (p <0.01) respectively, in obese than in normal-weight dogs while no difference was observed for ADIPOR1. Conclusion: ADIPOQ and ADIPOR2 expression in the skin appear negatively correlated with obesity. These findings evidence that the ADIPOQ system changes in the obese dog skin and suggest that ADIPOR2 regulates the ADIPOQ effect on the skin. This study opens interesting questions on the modifications of adipokines in the skin of obese animals. The experimental procedures were approved by the Ethical Animal Care and Use Committee (n.PG/2017/0099607) of the University of Naples Federico II.