Actions of PGLa-AM1 and its [A14K] and [A20K] analogues and their therapeutic potential as anti-diabetic agents

PGLa-AM1 (GMASKAGSVL10GKVAKVALKA20AL.NH2) was first identified in skin secretions of the frog Xenopus amieti (Pipidae) on the basis of its antimicrobial properties. PGLa-AM1 and its [A14K] and [A20K] analogues produced a concentration-dependent stimulation of insulin release from BRIN-BD11 rat clonal β-cells without cytotoxicity at concentrations up to 3 μM. In contrast, the [A3K] analogue was cytotoxic at concentrations ≥ 30 nM. The potency and maximum rate of insulin release produced by the [A14K] and [A20K] peptides were significantly greater than produced by PGLa-AM1. [A14K]PGLa-AM1 also stimulated insulin release from mouse islets at concentrations ≥ 1 nM and from the 1.1B4 human-derived pancreatic β-cell line at concentrations > 30 pM. PGLa-AM1 (1 μM) produced membrane depolarization in BRIN-BD11 cells with a small, but significant (P