Niacin lowers disease-causing triglycerides and boosts 'good' high-density lipoproteins. But it also triggers a burning 'flush' sensation in humans. Robert Lefkowitz and his colleagues at Duke University Medical Center in Durham, North Carolina, now report that niacin's benefits and side effects may occur through different pathways mediated by the same G-protein-coupled receptor, GPR109A.
When the team exposed human cells expressing GPR109A to niacin, a protein called β-arrestin 1 flocked to the receptor, triggering a downstream flood of the molecule arachidonate, which causes the flushing response. In mice lacking β-arrestin 1, niacin improved fatty acid levels with minimal flushing. Lefkowitz, founder of a company seeking drugs targeting G-protein-coupled receptors, suggests the results could help scientists to find treatments with niacin's benefits but no flush.