“In normal control … slices, capsaicin induced a drastic pERK expression in superficial dorsal horn neurons, which … suppressed by morphine (10 μM), the selective μ-opioid receptor agonist DAMGO [[d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (1 μM)], and … selective CB1 receptor ACEA agonist [arachidonyl-2′-chloroethylamide (5 μM)].”
“In the adjacent L4 spinal segment, both DAMGO and ACEA significantly suppressed pERK induction by capsaicin.”