Low-Molecular-Mass Fragments of Collagen Improve Parameters Related to Mass and Inflammation of the Adipose Tissue in the Obese Rat

Abstract

Research background. Despite clearly recognized links between increased body mass and increased risk for various pathological conditions, therapeutic options to treat obesity are still very limited. The aim of the present study was to explore the effect of low molecular mass collagen fragments obtained from the scales of Antarctic wild marine fish on rats' visceral and subcutaneous white adipose tissue in a high-calorie diet-induced obesity model. Experimental approach. The study was conducted on outbred rats, which were divided into 3 experimental groups: the first - control, consuming standard food (3.81 kcal/g), the second - obese group, consuming a high-calorie diet (5.35 kcal/g), and the third – obese group, consuming a high-calorie diet (5.35 kcal/g) with intragastric administration of low molecular mass collagen fragments (at a dose 1 g/kg of body mass during 6 weeks). Low molecular collagen fragments were obtained by procedure which included collagen extraction from fish scales and enzymatic hydrolysis with pepsin. Apart from H&E staining, fibrosis level was assessed by histochemical Van Gieson trichrome picrofucsin staining and analyses of mast cells were performed by toluidine blue O staining. Results and conclusions. Group treated by low molecular mass fragments of collagen exhibited decreased rate of mass gain, relative mass, area occupied by collagen fibers of both visceral and subcutaneous adipose tissue and reduction of cross-sectional area of both visceral and subcutaneous adipocytes. Treatment by low molecular mass fragments of collagen reduced infiltration of immune cells, number of mast cells and their redistribution back to the septa. This was as well accompanied by decreased number of the crown-like structures formed by immune cells, which are markers of chronic inflammation that accompany obesity. Novelty and scientific contribution. This is the first study which reported the anti-obesity effect of low molecular mass fragments produced as a result of controlled hydrolysis of collagen from the scales of Antarctic wild marine fish in vivo model. Another novelty of this work is observation that the tested collagen fragments not only reduce body mass, but as well improve morphological and inflammatory parameters (decrease in number of crown-like structures, immune cells infiltration, fibrosis and mast cells). Altogether, our work suggests that low molecular mass collagen fragments represent a promising candidate for amelioration of some comorbidities linked to obesity.