GHRP-6 and CJC-1295 without DAC (Modified GRF 1-29) are synthetic research peptides that are frequently used together in experimental models to investigate the regulation of the growth hormone axis and the signaling mechanisms of the pituitary. GHRP-6 is a hexapeptide growth hormone secretagogue that binds to the growth hormone secretagogue receptor (GHS-R1a) and activates Gq/PLC-dependent calcium signaling pathways involved in GH release. CJC-1295 without DAC is a stabilized analog of growth hormone-releasing hormone (GHRH 1-29) that activates the GHRH receptor and stimulates adenylate cyclase as well as cAMP-mediated signals. Preclinical studies show that combined GHS-R1a agonists and GHRH analogs are used to investigate synergistic somatotrophic signaling, hypothalamic-pituitary feedback, and peptide-mediated endocrine regulation.