Beneficial Effects of PKF275-055, a Novel, Selective, Orally Bioavailable, Long-Acting Dipeptidyl Peptidase IV Inhibitor in Streptozotocin-Induced Diabetic Peripheral Neuropathy

1-[(2-adamantyl)amino]acetyl-2-cyano-(S)-pyrrolidine, monohydrochloride (PKF275-055), a vildagliptin analog, is a novel, selective, potent, orally bioavailable, and long-acting dipeptidyl peptidase IV inhibitor. We studied the effect of PKF275-055 administration on the prevention, protection, and treatment of diabetic neuropathy in the streptozotocin-induced diabetic rat. PKF275-055 improved body and muscle weight. Oral glucose tolerance tests showed a marked improvement in glucose metabolism under all treatment schedules. When tested in prevention and protection experiments, PKF275-055 completely averted the decrease of Na+/K+-ATPase activity and partially counteracted the nerve conduction velocity (NCV) deficit observed in untreated diabetic rats but had no effects on abnormal mechanical and thermal sensitivity. When used in a therapeutic setting, PKF275-055 induced a significant correction in the alteration in Na+,K+-ATPase activity and NCV present in untreated diabetics. Diabetic rats developed mechanical hyperalgesia within 2 weeks after streptozotocin injection and exhibited significantly longer thermal response latencies. It is noteworthy that PKF275-055 treatment restored mechanical sensitivity thresholds by approximately 50% (p < 0.01) and progressively improved the alteration in thermal responsiveness. In conclusion, PKF275-055 showed an anabolic effect, improved oral glucose tolerance, and counteracted the alterations in Na+,K+-ATPase activity, NCV, and nociceptive thresholds in diabetic rats. The present data support a potential therapeutic effect of PKF275-055 in the treatment of rodent diabetic neuropathy.