Protein synthesis inhibitors (PSIs) increase the rate of degeneration, as measured by compound action potential (CAP) conduction, in segments of rat PNS and CNS axons. Sciatic axonal segments maintained in vitro in Krebs at 37-38 o C generate CAPs for 24h compared to 8h for axons exposed to Krebs containing two PSIs, 100μM anisomycin and/or 35μM cycloheximide. Spinal axonal segments at 37-38 o C generate CAPs for 3h compared to 2h for axons exposed to Krebs containing PSIs. While cooling (6-9 o C) slows degeneration rate, cooled sciatic axons exposed to PSIs exhibit lower peak CAPs compared to cooled control segments (P<0.005).