linoleic-acid and retinol-palmitate

To examine the effects of dietary β-carotene (βC) or retinyl palmitate (RP) on fatty acid (FA) profile and mRNA expression, samples were collected from 24 Angus-cross calves that were allotted to four treatments consisting of RP supplemented at 2200 IU/kg, and synthetic β-carotene (SβC) supplemented at one, five or 10 times RP. Longissimus muscle (LM) cis-9, trans-11 conjugated linoleic acid was greater in RP compared to SβC1X (P = 0.04). The polyunsaturated:saturated FA increased linearly (P = 0.04) in the LM as dietary SβC increased. Expression of βC oxygenase 2 (βCO2), an enzyme that cleaves β-carotene, was greater in the LM for SβC1X compared to RP and decreased linearly as SβC increased (P ≤ 0.02). Peroxisome proliferator activated receptor γ (PPARγ) expression in the LM increased in SβC1X compared to RP (P = 0.03); however, PPARγ and retinoic acid X receptor α (RXRα) expression decreased linearly (P = 0.02) in the LM with increasing SβC. Retinoic acid receptor α (RARα) expression tended (P = 0.10) to decrease linearly in the LM with increased SβC. In conclusion, SβC supplementation increased mRNA expression of some lipogenic genes in the LM, but increasing dietary SβC inhibited their expression and tended to increase polyunsaturated FA.

Topics: Animals; beta Carotene; Cattle; Diet; Dietary Supplements; Dioxygenases; Diterpenes; Fatty Acids, Unsaturated; Female; Gene Expression; Linoleic Acid; Lipogenesis; Male; Muscle, Skeletal; PPAR gamma; Retinoic Acid Receptor alpha; Retinyl Esters; RNA, Messenger; Vitamin A

Improving the bioavailability of beta-carotene is vital to manage vitamin A deficiency. The influence of micellar oleic (OA), linoleic (LA) and eicosapentaenoic (EPA) acids on plasma beta-carotene response and its conversion to retinol has been studied in rats employing single (9 h time course) and repeated (10 days) dose administrations. After a single dose, the levels (area under the curve) of plasma beta-carotene and retinyl palmitate in OA and EPA groups were higher (p < 0.05) by 13, 7 and 11, 6 folds than LA group. The liver beta-carotene level in OA and EPA groups were higher (p < 0.05) by 3 and 1.2 folds than LA group. After repeated dose, the plasma beta-carotene and retinyl palmitate levels in OA (6.2%, 51.7%) and EPA (25.4%, 17.23%) groups were higher (p < 0.05) than LA group. The liver beta-carotene level in OA (21.2%) and EPA (17.6%) groups were higher (p < 0.05) than LA group. In both the experiments, the activity of beta-carotene 15,15'-dioxygenase in the intestinal mucosa and plasma triglyceride levels were also higher in OA and EPA groups than LA group. beta-Carotene excreted through urine and feces of OA and EPA groups was lower than the LA group. These results demonstrate an improved absorption and metabolism of beta-carotene when fed mixed micelles with OA or EPA compared with LA. Although the mechanism involved in selective absorption of fatty acids needs further studies, intestinal beta-carotene uptake and its conversion to vitamin A can be modulated using specific fatty acids.

Topics: Animals; beta Carotene; beta-Carotene 15,15'-Monooxygenase; Diterpenes; Eicosapentaenoic Acid; Intestinal Absorption; Intestinal Mucosa; Linoleic Acid; Male; Micelles; Oleic Acid; Rats; Rats, Wistar; Retinyl Esters; Time Factors; Vitamin A

Conjugated linoleic acid (CLA) is a naturally occurring anticarcinogen found in milk fat and body fat of ruminants. Although CLA is an intermediate in ruminal biohydrogenation of linoleic acid, we hypothesized that its primary source was from endogenous synthesis. This would involve Delta(9)-desaturase and synthesis from trans-11 18:1, another intermediate in ruminal biohydrogenation. Our first experiment supplied lactating cows (n = 3) with trans-11 18:1 by abomasal infusion and examined the potential for endogenous synthesis by measuring changes in milk fat CLA. By d 3, infusion of trans-11 18:1 resulted in a 31% increase in concentration of cis-9, trans-11 CLA in milk fat, demonstrating that an active pathway for endogenous synthesis of CLA exists. Our second experiment examined the quantitative importance of endogenous synthesis of CLA in lactating cows (n = 3) by abomasally infusing a putative stimulator (retinol palmitate) or an inhibitor (sterculic oil) of Delta(9)-desaturase. Infusion of retinol palmitate had no influence on milk fatty acid desaturation, and yield of CLA in milk fat was not altered. However, sterculic oil infusion decreased the concentration of CLA in milk fat by 45%. Consistent with Delta(9)-desaturase inhibition, the sterculic oil treatment also altered the milk fat concentration of other Delta(9)-desaturase products as indicated by the two- to threefold increase in the ratios of 14:0 to 14:1(,) 16:0 to 16:1 and 18:0 to cis-18:1. Using changes in the ratio of 14:0 to 14:1 as an indication of the extent of Delta(9)-desaturase inhibition with the sterculic oil treatment, an estimated 64% of the CLA in milk fat was of endogenous origin. Overall, results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.

Topics: Animals; Anticarcinogenic Agents; Cattle; Diterpenes; Fatty Acid Desaturases; Female; Lactation; Linoleic Acid; Milk; Retinyl Esters; Stearoyl-CoA Desaturase; Stereoisomerism; Vitamin A

Decreased bile secretion into the intestine has been associated with low plasma concentrations of essential fatty acids (EFA) in humans. We studied the mechanism behind this relationship by determining the status and absorption of the major dietary EFA, linoleic acid (LA), in control and 1-week bile-diverted rats. The absorption of LA was quantified by a balance method and by measuring plasma concentrations of [13C]LA after its intraduodenal administration. Absolute and relative concentrations of LA in plasma were decreased in bile-diverted rats (P<0.01 and P<0.001, respectively). Fecal excretion of LA was increased at least 20-fold in bile-diverted rats (0.72+/-0.11 vs. 0.03+/-0.00 mmol/day; P<0.0001). Due to increased chow ingestion by bile-diverted rats, net intestinal absorption of LA was similar between bile-diverted and control rats (1.96+/-0.14 vs. 1.91+/-0.07 mmol/day, respectively; P>0.05). After intraduodenal administration of [13C]LA, plasma concentrations were approximately 3-4-fold lower in bile-diverted rats for at least 6 h (P<0.001). Plasma concentrations of both [12C]arachidonic acid and [13C]arachidonic acid were increased in bile-diverted rats (P<0.05). We conclude that decreased plasma concentrations of LA in 1-week bile-diverted rats are not due to decreased net intestinal absorption of LA, but may be related to increased metabolism of LA.

Topics: Animals; Arachidonic Acid; Bile; Body Weight; Dietary Fats, Unsaturated; Diterpenes; Food; Intestinal Absorption; Linoleic Acid; Male; Rats; Rats, Wistar; Retinyl Esters; Vitamin A