Prolonged stimulation with thyrotropin-releasing hormone and pituitary adenylate cyclase-activating polypeptide desensitize their receptor functions in prolactin-producing GH3 cells

► TRH and PACAP increased prolactin promoter in PAC1R-transfected GH3 cells. ► The functions of TRHR and PAC1R changed after prolonged treatment with TRH and PACAP were examined. ► After long treatment with TRH/PACAP, prolactin promoter by TRH/PACAP were diminished. ► Prolonged pretreatment with both TRH and PACAP desensitized their own and each other's receptors.