Denervation reduces extractable Met-enkephalin-like immunoreactivity in guinea-pig lips

Skin extracts of the upper lip of 18 guinea pigs were made and subjected to a Met-enkephalin radioimmunoassay 3-4 weeks, 8 weeks, and 12 weeks after transection of one infraorbital nerve. There was a significant reduction in the concentration of extractable Met-enkephalin-like immunoreactivity in the denervated half of the lip as compared to the innervated side. The reduction increased with time. These results show that the enkephalin content of the guinea pig upper lip depends on an intact innervation by the infraorbital nerve.