![Fig. 4. Effects of [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO) or fentanyl on morphine-induced analgesia and μ-opioid receptor (MOR) internalization. Rats were subjected to the hot plate test 5 min after intrathecal injection of indicated agonists (percent maximum possible effect [%MPE]; closed bars ). They were fixed quickly to determine the percentage of MOR immunoreactive neurons with internalization ( open bars ) (n = 5–8). * P < 0.05 compared with 2.5 μg morphine.](https://asa2.silverchair-cdn.com/asa2/content_public/journal/anesthesiology/105/3/10.1097_00000542-200609000-00023/2/23ff4.png?Expires=1716587365&Signature=cAnFX-s12Yv0wzWOl35OctxPKxRXV~lQZQQr2q5gT93aEnJFgBaEfM1xV~DFYup6XWMECX0nntcJPkVIkn9YWHZ9bjLtn4nKm2vd6LnKxo9OXKf18AcFkzGdBZFDK8-61HfEu241bw3NG-OFEkUCE90Y2ng2qvRuDZL-X2qPuI7oyOvr~PnM-MCvydpASl-Fnzs~XT3onPeiUcCSgpN3uVCdYcJT0HTD-Adngs~1OoJfoRMrEHbECZ0pSPZVTY6fRolLNSmZNgZLXSJNBh~ROTV3rlVbk3w1AoZSfoLnc44WUE4NycExd2qgxuCKtOKcAraQC9tfSvtGxpE0dI7Euw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Fig. 4. Effects of [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO) or fentanyl on morphine-induced analgesia and μ-opioid receptor (MOR) internalization. Rats were subjected to the hot plate test 5 min after intrathecal injection of indicated agonists (percent maximum possible effect [%MPE]; closed bars ). They were fixed quickly to determine the percentage of MOR immunoreactive neurons with internalization ( open bars ) (n = 5–8). * P < 0.05 compared with 2.5 μg morphine.
