Intestinal metabolism of plasma free fatty acids in streptozotocin diabetic rats

Abstract

Moderate insulin deficiency was reported to be accompanied by an increased production of intestinal very low density lipoprotein (VLDL) triglyceride in the rat. Because plasma free fatty acids (FFA) are incorporated into triglyceride by intestinal mucosa of rats and humans and plasma FFA are increased in insulin-deficient diabetes mellitus, we investigated several aspects of the intestinal metabolism of plasma FFA in diabetic rats. All experiments were performed on the third day following the i.v. injection of streptozotocin (45 mg/kg body weight) or buffer alone. A (14 C)palmitic acid-rat serum complex was rapidly injected intravenously and its initial uptake by small bowel mucosa, the intracellular incorporation into lipids and water soluble metabolites and the specific radioactivity of triglycerides of mucosal homogenates was determined. No significant differences could be found between diabetic and control rats at 2 and 5 min after 14C-palmitate i.v., suggesting that neither the influx of plasma free fatty acids into intestinal mucosal cells nor their initial intracellular metabolic pathways are significantly altered in moderately diabetic rats. A pronounced decrease in intestinal mucosal triglyceride at 10 min after 14C-palmitate i.v. might be interpreted as indirect evidence for an enhanced triglyceride efflux from intestinal mucosa into mesenteric lymph in diabetic rats.

An Updated Perspective on the Dual-Track Model of Enterocyte Fat Metabolism

“…(Re)esterification of basolaterally absorbed FFA and glycerol: Basolateral uptake of circulating fatty acids by enterocytes has been well established in animal models [13,16,17,66,67]. There is also human in vivo evidence of basolateral uptake as an ultimate source of TRL-TG: 14 C-palmitate infused intravenously was recovered within minutes in jejunal biopsy homogenates [68], and IV-infused deuterated glycerol reappeared within circulating chylomicron-TG [69].…”