gnih neurons reside primarily in the dorsomedial nucleus of the hypothalamus (humans and rodents) and the paraventricular nucleus of the hypothalamus (avian species). some gnih neuron terminals in both mammalian and avian species project to the median eminence. gnih and gnrh (gonadotropin releasing hormone) neurons exist in close proximity in the hypothalamus, which may enable the direct inhibition of gnrh neurons by gnih. gnih enters the bloodstream via the hypothalamo-hypophyseal portal system, the vascular network supplying both the hypothalamus and the pituitary.