Enrichment of the rats diet with docosahexaenoic acid and astaxanthin: physiological and biochemical efficiency
To investigate the effect of enrichment of the rats diet with polyunsaturated fatty acids (PUFA) ω-3 (220 mg docosahexaenoic acid per 1 kg of animal body weight per day) and astaxanthin (5 mg/kg body weight) on serum corticosterone concentration, physical fatigue, anxiety of rats after exhausting the load. During 30 days the rats of the test group received the diet in which the usual fat component comprising sunflower oil and lard (1:1) was completely replaced by the mixture of oils (high oleic sunflower (89%), coconut (6%), and marine oil from microalgae Schizochytrium sp. (5%) with a high content of docosahexaenoic acid with the addition of astaxanthin). Ratio of ω-6 and ω-3 PUFA in the lipid component of the experimental diet was 5.2:1 (n=12) and 135:1 in the diet of rats in the control group (n=12). DHA enrichment of the diet resulted in a significant 10-fold increase of the DHA liver content and ω-6 PUFA reducing (in particular of linoleic acid in 2.7-fold). No significant differences have been identified between the groups in terms of anxiety, estimated on the elevated plus maze at the beginning and on 24th day of the experiment. Results of the exhausting load on a treadmill (25th day) showed a significant reduction in physical fatigue in rats of the experimental group compared with the control group of rats: the number of contacts with the electrical grid was 4.2±0.9 versus 19.7±4.4, fulltime shock was 0.9±0.2 versus 3.3±0.8 sec. Significantly lower serum corticosterone concentration took place in the subjected to exhausting exertion animals receiving lipid module (15.0±3.9 ng/ml) compared to control animals (31.0±5.4 ng/ml). Thus, modification of the lipid component of the diet by its enrichment with DHA and astaxanthin led to decrease of the rat fatigue during exercise training (test treadmill) and prevent from the serum corticosterone raise, that indicates animal stress adaptation ability.
Keywords:lipid module, docosahexaenoic acid, astaxanthin, forced running stress, anxiety, physical fatiguability, corticosteron