Effects of body weight reduction on blood adipokines and subcutaneous adipose tissue adipokine mRNA expression profiles in obese ponies.

This research explored how weight loss impacts fat-related hormones and the expression of related genes in the fat tissues of obese ponies. It concludes that these hormones and genes are closely linked to insulin resistance and fat levels, but the role fat tissue plays in this relationship is still uncertain.

Objective and Method

• The objective of the study was to investigate the effects of weight loss on blood adipokines (proteins secreted by fat cells) and the mRNA expression profiles (the measure of gene activity) of adiponectin, retinol-binding protein 4 (RBP4), interleukin 6 (IL-6), and macrophage activation marker (CD68) in the subcutaneous fat tissues of obese ponies.
• A total of 15 obese ponies were involved in a weight reduction programme, where their daily energy intake was between 7.0 and 8.4 MJ/100 kg of their body weight.
• The pony’s insulin sensitivity was evaluated through a frequently sampled intravenous glucose tolerance test. The researchers further sampled subcutaneous fat tissues from the tails of these ponies for gene expression profiling.
• Blood samples were taken for the analysis of serum leptin, serum RBP4 and plasma adiponectin before and after the weight reduction programme.

Findings

• The ponies exhibited significant weight loss when their daily energy intake was 7 MJ/100 kg of their body weight.
• The levels of serum leptin and RBP4 were initially uniform across insulin-resistant (IR) and insulin-sensitive (IS) ponies, but they significantly decreased during the weight loss programme.
• IR ponies exhibited significantly lower plasma adiponectin levels compared to IS ponies at the start of the study.
• The initial gene expression profiles of RBP4, adiponectin, IL-6, and CD68 were similar in both IR and IS ponies.
• The study shows that plasma adiponectin strongly related to insulin resistance, while serum leptin and RBP4 closely linked to the fat levels of the ponies, regardless of their insulin sensitivity.
• The gene expression profiles in the adipose tissue didn’t clearly reflect these relationships.

Conclusion

• The exact role of subcutaneous adipose tissue in relation to insulin resistance remains unclear based on this study. Despite the changing levels of adiponectins in the blood, the corresponding gene activity in the adipose tissue failed to reflect these changes.