Structural and biochemical effects of essential fatty acid deficiency on peripheral nerve

The effect of postweaning essential fatty acid (EFA) deficiency on the peripheral nerve was studied in groups of rats. At 325 days, the characteristic biochemical changes of EFA deficiency were present in isolated peripheral myelin, although to a lesser degree than reported in non-neural tissues. There was no significant difference between control and deficient groups in number or size distributions of myelinated fibers (MFs) in muscle and sensory nerves, in the incidence of teased fiber abnormalities, in rates of axonal transport of dopamine-beta-hydroxylase and acetylcholinesterase, or in conduction velocity and compound action potentials of peripheral nerve in vivo or in vitro. Four weeks after a standard sciatic crush injury, the median MF diameter in regenerated peroneal nerves was significantly smaller in EFA-deficient rats than in control rats, but this difference was no longer significant at 18 weeks. At 18 weeks, EFA-deficient and control regenerated nerves showed similar myelin periodicity and relationship of axonal area to number of myelin lamellae. We conclude that acquired EFA deficiency in the rat leads to biochemically abnormal peripheral myelin, but that this state is unaccompanied by clinical, physiological, or morphological evidence of neuropathy.