Growth hormone releasing hormone (GHRH) is a peptide synthesized in the cell bodies of neurosecretory neurons in the ventromedial and arcuate nuclei of the hypothalamus. When stimulated, GHRH travels down the axons of these neurons and is released into the hypophyseal portal circulation. GHRH binds to receptors on somatotrophs in the anterior pituitary, resulting in growth hormone (GH) gene expression and the secretion of GH. This positive regulation of GH by GHRH is opposed by somatostatin, which is synthesized in neurosecretory cell bodies located in the anterior paraventricular region of the hypothalamus.