Suppression of Acute Herpetic Pain-Related Responses by the (cid:1) -Opioid Receptor Agonist ( (cid:1) )-17-Cyclopropylmethyl-3,14 (cid:2) -dihydroxy-4,5 (cid:3) -epoxy-6 (cid:2) -[ N -methyl-3- tran s-3-(3-furyl) Acrylamido] Morphinan Hydrochloride (TRK-820) in Mice