In addition, each Herring body also contains ATP and a type of neurophysin. Neurophysins are binding proteins, of which there are two types: neurophysin I and neurophysin II, which bind to oxytocin and ADH, respectively. Neurophysin and its hormone become a complex considered a single protein and stored in the neurohypophysis. Upon stimulation by the hypothalamus, secretory granules release said hormones into the bloodstream. Fibers from supraoptic nuclei are concerned with ADH secretion; paraventricular nuclei with oxytocin.