Neurotrophic influences are not affected by miniature end-plate potentials

We investigated whether or not miniature end-plate potentials (MEPPs) play a part in neurotrophic influences. The sciatic nerve of mice, which supplies the extensor digitorum longus muscles, was cut either close to, or far from, the muscle. Denervation changes were evaluated using the resting membrane potential and dose-response curves obtained by plotting acetylcholine-induced contractures of muscles denervated 3 days earlier. The cessation of MEPPs and the manifestation of denervation changes occurred significantly later in muscles with long nerve stumps than in those with short nerve stumps. A single administration of ethidium bromide, a specific inhibitor of mitochondrial protein synthesis, accelerated the cessation of MEPPs in muscles with long nerve stumps without affecting the manifestation of denervation changes. We therefore conclude that MEPPs do not have neurotrophic effects.