Characterization of Feline Adiponectin and its Association with Metabolic Indices in Lean and Obese Cats

Adipose tissue secretes over 100 different proteins and cytokines called adipokines. Adiponectin is one of the most intriguing adipokines because it is closely associated with insulin sensitivity and is an early marker for Type-2 diabetes mellitus in human beings. Cats are at risk for developing Type-2 diabetes with obesity, so it is important for researchers to understand the role adipokines, like adiponectin, play in feline metabolism. This project sought to lay the foundation for future research regarding feline adiponectin by sequencing adiponectin cDNA, measuring adiponectin’s expression in various tissues, validating and developing new techniques for measuring adiponectin in circulation, determining the influence of gender on adiponectin concentrations, and by monitoring changes in adiponectin as cats gain and lose fat mass.

The results of this project revealed that adiponectin has a similar cDNA and amino acid sequence to other species and is secreted almost exclusively from adipose tissue. However, cats differed from other species in that visceral adipose tissue had more adiponectin expression than subcutaneous adipose tissue. Serum feline adiponectin was measured using a commercially available murine adiponectin ELISA, and the high molecular weight (HMW) form was detected using gel chromatography combined with ELISA. Neutered male cats may have lower concentrations of total adiponectin than female cats and lower percentages of HMW adiponectin than all other gender groups. Similar to humans, HMW adiponectin was more closely associated with improved glucose metabolism than total adiponectin. HMW adiponectin also correlated more closely with body fat mass than total adiponectin. Despite some unique characteristics, feline adiponectin appears similar in structure and function to adiponectin in other species.