OBJECTIVES/GOALS: This study aimed to investigate the mechanistic effects of fish oil (âμ-3 fatty acids) or evening primrose oil (âμ-6 fatty acids) supplementation on platelet reactivity in postmenopausal women. METHODS/STUDY POPULATION: Postmenopausal women were recruited from the Ann Arbor community and the University of Michigan Medicine Center. All subjects were recruited under study protocols approved by the University of Michigan IRB between November 2015 and March 2017. We conducted a randomized, double-blind, two-period crossover trial, consisting of a 60-day supplementation period followed by a 14-day washout period in between and at the end of the study. Subjects were treated daily in random order with 2g of fish oil supplement and 2g of evening primrose oil. Blood was drawn at baseline, post-supplementation, and after washout. The effects of fatty acid supplementation on platelet aggregation, dense granule secretion and activation of basal integrin âºIIbÎ23 were assessed following supplementation and washout period. RESULTS/ANTICIPATED RESULTS: The study started with 90 postmenopausal women. A total of 78 subjects completed the study, with 12 subjects dropping out due to non-compliance and medical reasons. Supplementation with fish oil attenuated the thrombin receptor PAR4-induced platelet aggregation, whereas primrose oil supplementation attenuated aggregation mediated by PAR4 or collagen. Supplementation with âμ-3 or âμ-6 fatty acids decreased platelet dense granule secretion and attenuated basal levels of integrin âºIIbÎ23 activation. Post-washout following supplementation with primrose oil, the thrombin receptor PAR1-induced platelet aggregation was similarly attenuated. For either treatment, the observed effects post supplementation on dense granule secretion and basal integrin activation were sustained after the washout. DISCUSSION/SIGNIFICANCE: Postmenopausal women are at increased risk for a cardiovascular event due to platelet hyperactivity. This study indicates that supplementation with âμ-3 and âμ-6 fatty acids may offer significant protection for postmenopausal women against cardiovascular diseases and occlusive thrombotic events by reducing platelet reactivity.