Preheat the oven to 425° F. Butter an 8½" x 4½" loaf pan.
In a large bowl, whisk together the flours, oats, wheat germ and bran, flaxseed, brown sugar, salt and baking soda.
Stir the pistachios into the mixed dry ingredients.
In a medium bowl, whisk together the buttermilk, egg, and melted butter.
Add the wet ingredients to the dry ingredients and mix together. The batter will be wet and very sticky.
Transfer the batter to the prepared pan, spread it evenly, and sprinkle the batter with the reserved oats (about ¼ c.)
Bake the loaf in the preheated oven for about 35 mins. or so, or until a toothpick inserted in the center comes out cleanly.
Cool loaf on a rack before removing from the pan and slicing.