A high linoleic acid diet exacerbates metabolic responses and gut microbiota dysbiosis in obese rats with diabetes mellitus

Dietary polyunsaturated fatty acid (PUFA) levels may affect inflammatory responses and lipid metabolism.

Unexpected depletion of plasma arachidonate and total protein in cats fed a low arachidonic acid diet due to peroxidation

An opportunity to investigate a low-arachidonic acid (AA) feline diet possibly related to elevated peroxide value (PV) during storage on plasma phospholipid (PL) and reproductive tissue fatty acid (FA) profiles presented itself in the present study. Cats (nine animals per group) had been fed one of three dry extruded, complete and balanced diets for 300 d before spaying. The diets contained adequate AA (0·3 g/kg), similar concentration of antioxidants and were stored at ambient temperature, but differed in FA composition. The diets were designated as follows: diet A (high linoleic acid), diet B (high γ-linolenic acid) and diet C (adequate linoleic acid). Diet samples that were obtained the week before spaying revealed an elevated PV of diet A v. diets B and C (135 v. 5·80 and 2·12 meq/kg fat, respectively). Records revealed decreased food consumption of diet A cats beginning at 240 d but without weight loss; thus an opportunity presented to investigate diet PV effects. Total plasma protein and PL-AA concentrations in group A were significantly decreased at 140 and 300 d. Uterine and ovarian tissues collected at surgery revealed modest decrements of AA. Diet A was below minimum standards at 0·015 % (minimum 0·02 %), probably due to oxidation. The time at which diet A became unacceptable may have occurred between 60 and 140 d because plasma PL-AA was within our normal colony range (approximately 4–7 % relative) after 56 d of feeding. High-linoleic acid-containing diets may be more likely to be oxidised requiring additional antioxidants. The findings suggest that reduced plasma protein in combination with plasma AA concentrations may serve as biomarkers of diet peroxidation in cats before feed refusal, weight loss or tissue depletion.

Dietary Protein Level and Dietary Interaction Affect Quinolinic Acid Concentration in Rats

During tryptophan-niacin conversion, hepatic α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) [EC4.1.1.45] plays a key role in regulating NAD biosynthesis. ACMSD activity is greatly affected by many factors such as nutritional status and disease. The tryptophan catabolite quinolinic acid has been reported to be associated with the pathogenesis of various disorders and is a potential endogenous toxin. However the effects of dietary protein levels or dietary interaction between protein levels and fatty acid type to this process have not been investigated and are still unknown. In this study, we examined whether dietary protein level, fatty acid type, namely saturated fatty acid and polyunsaturated fatty acid, and their interaction affect serum quinolinic acid concentration in rats. Male Sprague-Dawley rats (4-weeks old) were fed with 20% casein + 10% stearic acid diet (20C10S), 20% casein + 10% linoleic acid diet (20C10L), 40% casein + 10%stearic acid diet (40C10S), or 40% casein + 10% linoleic acid diet (40C10L) for 8 days, and serum quinolinic acid concentration and ACMSD activity were determined. Serum quinolinic acid concentration was significantly increased in the 40C10L group compared with other three groups. There was also the negative correlation between the sum of liver and kidney ACMSD activities, and serum quinolinic acid concentration per tryptophan intake (r = 0.8209, p < 0.01). Increased serum QA concentrations are probably due to a decreased ACMSD activity.