A lipoic acid gamma linolenic acid conjugate is effective against multiple indices of experimental diabetic neuropathy

Untreated streptozotocin-diabetic (7 weeks duration) rats showed reductions (all p < 0.01; percentages in brackets) in motor and sensory nerve conduction velocity (MNCV; 14 %, SNCV; 17 %) and in sciatic nerve contents of nerve growth factor (NGF; 57%), substance P (SP; 53 %) and neuropeptide Y (NPY; 39 %). Treatment with a gamma-linolenic acid-alpha-lipoic acid conjugate (GLA-LA; 35 mg . day(-1) . rat(-1)) attenuated (p < 0.05) these reductions to MNCV (8%), SNCV (5 %), NGF (19 %), SP (23 %), NPY (20 %), such that the values in GLA-LA-treated diabetic rats did not differ significantly from those of control non-diabetic animals. Treatment with alpha-lipoic acid alone at 100 mg/kg i. p. was without effect on these variables except for NGF (33 % reduction, p < 0.05) and treatment with the antioxidant, butylated hydroxytoluene (1.5% dietary supplement) did not affect any deficits. These data show that GLA-LA is effective in improving both electrophysiological and neurochemical correlates of experimental diabetic neuropathy.