Bioenergetic functions of mitochondria in liver, pancreatic acinar cells, and sperm cells of rats fed short-term high-fat or high-fat high-sugar diets

Abstract

An unhealthy diet often is a cause of obesity, chronic inflammation, and metabolic disruption in multiple organs. However, the direct influence of elevated lipid or sugar consumption on liver, pancreatic, and sperm mitochondria is not well understood. The aim of the study was to investigate the functional activity of mitochondria of liver, pancreatic acinar cells, and sperm cells in rats on a short-term (7 weeks) diet with high fat or high fat and high sugar content. Male Wistar rats were on a basic, high-fat or high-fat high-sugar diet for 7 weeks. At the end of the experiment, visceral fat mass, blood glucose and lipids were measured. Mitochondrial functional activity was evaluated with oxygen consumption assay. In isolated pancreatic acinar cells, NAD(P)H autofluorescence and mitochondrial membrane potential were also studied. No difference in body mass was observed between the 3 groups at the end of the experiment. Visceral fat mass was slightly but significantly elevated in rats on a high-fat high-sugar diet. Both diets did not affect plasma glucose or triglyceride levels but caused a modest elevation of total plasma cholesterol. Respiration and oxidative phosphorylation of isolated liver mitochondria were not affected by any experimental diet. In pancreatic acinar cells, a high-fat diet caused a significant decrease of basal respiration by ~15%, but no effects were observed on the maximal rate of uncoupled respiration, mitochondrial membrane potential, or NAD(P)H autofluorescence. In these cells, a ketone body 3-hydroxybutyrate caused elevation of uncoupled respiration and NAD(P)H level irrespectively of the diet. Diets did not cause any change in sperm concentration, viability or motility. Surprisingly, in animals on a high-fat high-sugar diet, a significant increase in both basal and maximal respiration of sperm cells was observed. Collectively, these data show that while the elevated fat and sugar content in the diet does not cause significant obesity, no detrimental effects on mitochondria of the liver, pancreas, and sperm cells are observed. Keywords: diet, liver, mitochondria, pancreatic acinar cells, sperm