Investigating Effects of eugenol on nerve conduction and synaptic transmission at neuromuscular junction in an amphibian

Department of Biology, University of Kentucky, Lexington, KY, USA

Eugenol is a natural anesthetic. This study provides insights into how eugenol affects neuro- muscular communication in a vertebrate to address its anesthetic property. Eugenol’s effects at the neuromuscular junction (NMJ) have not been well studied. This study was to determine if eugenol affects the activity of cholinergic synapses at the frog pectoris NMJ. Second, this study set out to determine if eugenol could block evoked compound action potentials (CAP) in the frog sciatic nerve at 0.05 mM. This study also provides a novel procedure for isolating the frog cutaneous pectoris muscle. This thin surface muscle is ideal to use in studying synaptic responses. The results showed evoked excitatory junction potentials at the frog pectoris NMJ were depressed during exposure to eugenol, however, quantal events were not. This indicated that the nicotinic acetylcholine receptors on the muscle fibers were not blocked by eugenol. Eugenol also depressed conduction of compound action potentials along the frog sciatic nerve. These results indicate eugenol likely targets membrane proteins associated with electrical signaling. In summary, this study successfully demonstrated use of the sciatic nerve and cutaneous pectoris muscle for examining the effects of eugenol on neural-muscular function and could potential be extended for use as an anesthetic.

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