Beta-carotene is incorporated or mobilized along with triglycerides in bovine adipose tissue in response to insulin or epinephrine.
Pasture fed cattle ingest substantial amounts of beta-carotene (beta-C). Not all of the carotenoid compound is transformed into vitamin A, but the surplus is deposited in adipose tissue (AT). The mechanisms of beta-C incorporation and mobilization are unknown. Two experiments were conducted using explants from bovine AT cultured in vitro. First, beta-C incorporation by explants from three animals was examined with different beta-C concentrations (0, 1, 5 and 20 microm) and different times of incubation (every 5 h up to 25 h). The data showed a significant increase of beta-C concentration in explants only for 20 microm beta-C. Secondly, effects of insulin and epinephrine on beta-C and triglyceride (TG) contents of explants were studied. Explants from six animals were incubated with either hormone and 0 or 20 microm beta-C for 20 h. Both TG and beta-C contents were affected positively by insulin and negatively by epinephrine. Interestingly, changes in ratios of beta-C/TG (hormone vs. control) were similar (1.7 x 10(-3) and 1.8 x 10(-3)), respectively, for insulin and epinephrine, indicating that beta-C level is directly related to TG content. We also report the presence of mRNA for beta-C 15, 15' oxygenase in bovine AT. The in vitro culture system using explants from bovine AT is a promising model to investigate factors that might affect the accumulation and metabolism of beta-C.
Arias
E
E
Posgrado en Ciencias de la Producción y la Salud Animal, Universidad Nacional Autónoma de México, Querétaro, México.
González
A
A
Shimada
A
A
Varela-Echavarria
A
A
Ruiz-López
F
F
During
A
A
Mora
O
O
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D046508:Culture Techniques / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D006109:Poaceae; D014280:Triglycerides / Q000378:metabolism*; D019207:beta Carotene / Q000493:pharmacokinetics*
D007328:Insulin; D014280:Triglycerides; D019207:beta Carotene; D004837:Epinephrine