In an experimental chronic migraine model induced by intermittent intraperitoneal injection of NTG in which the effect of chronic ghrelin treatment on endogenous pituitary adenylate cyclase-activating polypeptide (PACAP) and associated symptoms of migraine was investigated, photophobia and anxiety-like behaviors were determined by the modified EPM and the light/dark box tests [67]. The gene discussed is GHRL; the disease is migraine disorder.