Preheat oven to 400F. Combine oats and buttermilk in small bowl; set aside and let stand. Combine flour, baking powder, soda, salt, brown sugar, stir well. Add egg and melted butter to oats. Add dry ingredients and stir just until all is moistened. Gently fold in blueberries. Spoon into muffin pan until three-quarters full each. Bake for 17 to 20 minutes.