Ipamorelin and CJC-1295 without DAC (Mod GRF 1-29) are synthetic research peptides that are used together in experimental models to investigate the regulation of the growth hormone axis and mechanisms of somatotropic signaling. Ipamorelin is a selective pentapeptide growth hormone secretagogue that acts as an agonist of the growth hormone secretagogue receptor (GHS-R1a), activating the Gq/PLC- and calcium-dependent intracellular signaling pathways involved in GH release, while it shows only minimal interactions with other pituitary hormones in preclinical systems. CJC-1295 without DAC is a stabilized analogue of the growth hormone-releasing hormone (GHRH 1-29), which selectively activates the GHRH receptor, stimulates adenylate cyclase and the cAMP-mediated signaling pathway in pituitary somotropes. Preclinical research uses the combined activation of GHS-R1a- and GHRH receptors to study synergistic GH secretion, hypothalamic–pituitary feedback mechanisms, and the pharmacology of endocrine receptors in controlled laboratory conditions.