PARP1 and peripheral neuropathy: However, studies reported that PARP1/2 (Poly(ADP-ribose) polymerase 1/2), an enzyme that promoted NAD+ degeneration, promoted the development of chemotherapy-induced peripheral neuropathy.22,23 Whether PARP1/2 induced inhibition effect on NAD+ content in icariin-treated PINP rats was unknown.