Hypothalamic–pituitary–gonadal axis in which the hypothalamus and pituitary direct neuroendocrine function. The hypothalamus is located in the brain and secretes GnRH. GnRH travels down the anterior portion of the pituitary via the hypophyseal portal system and binds to receptors on the secretory cells of the adenohypophysis. In response to GnRH stimulation these cells produce LH and FSH, which travel into the blood stream. These two hormones play an important role in communicating to the gonads. In females FSH and LH act primarily to activate the ovaries to produce estrogen and inhibin and to regulate the menstrual cycle and ovarian cycle. Estrogen forms
Pituitary adenylate cyclase-activating peptide a maladaptive psychological response to traumatic, i.e. existence-threatening, events. Ressler et al. identified an association of a SNP in the gene coding for pituitary adenylate cyclase-activating polypeptide (PACAP), implicating this peptide and its receptor (PAC1) in PTSD. Pituitary adenylate cyclase-activating peptide has been shown to interact with secretin receptor. Pituitary adenylate cyclase-activating peptide Pituitary adenylate cyclase-activating polypeptide also known as PACAP is a protein that in humans is encoded by the "ADCYAP1" gene. PACAP is similar to vasoactive intestinal peptide. One of its effects is to stimulate enterochromaffin-like cells. It binds to vasoactive intestinal peptide receptor and to the PACAP