Elevated Plasma Adiponectin Level and Peripheral Blood Leukocyte Adiponectin Receptor Expression in Dogs Suffering from Insulin Deficiency

Abstract

The aim of this study is to determine and compare the effect of obesity or insulin deficiency on plasma adiponectin level and peripheral blood leukocyte (PBL) adiponectin receptor 1 and 2 (ADIPOR1 and -R2) expression in dogs. Obese and insulin deficient (ID) dogs demonstrated a significant reduction (60% lower) and significant increase (2x higher) in circulating adiponectin level, respectively, as compared to normal controls. PBL ADIPOR1 and -R2 mRNA expression was also significantly higher in obese (R1=333 mean fold higher, R2=64 mean fold higher) and ID dogs pre- insulin treatment (R1 =48 mean fold higher, R2=16 mean fold higher) as compared to normal PBL. Insulin treatment reduced ADIPOR1 (3 mean fold higher) and -R2 (1.5 mean fold higher) expression back down closer to control PBL levels in ID animals. The upregulation of adiponectin receptor expression might reflect an increased need for adiponectin signaling; however, the increase may have a different implication between obese and ID dogs. This may be due to adiponectin's contradictory paradoxical dual role, having both anti-inflammatory and pro-inflammatory properties on peripheral leukocytes, especially on monocytes depending on the biological context and adiponectin isoform.