An endogenous neuropeptide agonist of SST1-SST5 (IC50s = 0.5-18.2 nM for human receptors expressed in CCL39 cells); [KC1] competitively inhibits hexarelin binding to GHS-R in pituitary membranes (Ki = 0.54 μM); activates the human MrgX2 receptor expressed in HEK293 cells (EC50 = 1.3 μM); completely inhibits TRH, and partially inhibits VIP, stimulation of cAMP production in GH4 cells (0.01-1 μM); dose-dependently impairs memory retention in mice when delivered after foot shock avoidance training (0.05-5 μg, i.c.v.); dose-dependently reduces growth hormone secretion in rats with a reduction of over 80% at all concentrations after 10 minutes (40-320 μg/kg s.c.)