Fish Oil-induced Yellow Fat Disease in Rats. III. Lipolysis in Affected Adipose Tissue

Abstract

Abstract. Basal and hormone-stimulated lipolysis of adipose tissue was measured at successive stages during the development of fish oil-induced yellow fat disease in rats. Changes of lipolytic activity at an early stage of yellow fat disease were not seen. There was a significant increase of basal lipolysis and a decrease of stimulated lipolysis when many fat cells were affected (stage E). Since the increased basal lipolysis probably originates from degenerated fat cells, the mechanism of enzyme activation is not clear.The decreased stimulated lipolysis was proportional to the number of affected fat cells and resulted from membrane damage of these cells. Increased 5-nucleotidase activity, seen in affected fat cells, may be important, to this reduced stimulated lipolysis.

Isolation of Adipose Tissue Immune Cells

“…Although the presence of immune cells in inflamed AT had been described previously 2 , the seminal papers by Weisberg et al and Xu et al published in 2003 were the first to document the accumulation of AT macrophages (ATMs) in obesity, which secrete inflammatory cytokines and correlate with AT-specific and systemic insulin resistance 3,4 . These observations served as the basis of a new field of investigation recently coined, "immunometabolism," 5 and have been followed up by studies implicating various immune cell populations, including dendritic cells 6 , mast cells 7 , T cells [8][9][10] , B cells 11 , NKT cells 12 , eosinophils 13 , and neutrophils 14,15 in the development of obesity associated insulin resistance.…”