Dietary docosahexaenoic acid-enriched phospholipids normalize urinary melatonin excretion in adult (n-3) polyunsaturated fatty acid-deficient rats

Melatonin (MEL) plays an essential role in physiologic functions associated with darkness. We examined the effects of docosahexaenoic acid (DHA)-enric hed phospholipids from pig brains (BPL) or hen eggs (EPL), as sources of DH A, on lipid FA composition of pineal membranes and daytime and nighttime co ncentrations of 6-sulfatoxymelatonin (aMT6) in adult male control and (n-3) -deficient rats fed BPL and EPL diets for 5 wk. In two experiments, at 3 wk of age, rats were divided into subgroups and fed semipurified diets contai ning either peanut oil [(n-3)-deficient group] or peanut plus rapeseed oil (control group) and two dietary formulas containing either 3.5 g/100 g diet of BPL (Experiment 1) or 5.0 g/100 g diet of EPL (Experiment 2). BPL and E PL diets provided similar to 200 mg of DHA/100 g diet. During the daytime, aMT6 concentrations were not significantly different among groups. Converse ly, the (n-3)-deficient rats had significantly lower nighttime aMT6 concent rations than the control rats. BPL and EPL did not affect urinary nighttime aMT6 concentration in the control group, whereas (n-3)-deficient + BPL or EPL groups exhibited significantly higher nighttime aMT6 concentrations tha n the (n-3)-deficient group (76 and 110%, respectively). The level of DHA w as significantly higher in the pineal glands of control rats than in (n-3)- deficient rats. In rats fed EPL and BPL, the level of DHA reached a plateau , between 10 and 11 mg/100 mg total fatty acids in control + BPL or EPL and (n-3)-deficient + BPL or EPL groups. These findings suggest that new DHA-e nriched formulas may be used as an efficient alternative source of (n-3) po lyunsaturated fatty acids to normalize MEL secretion.