2-Deoxy-D-glucose analgesia: influences of opiate and non-opiate factors

Acute administration of 2-deoxy-D-glucose (2-DG), an antimetabolic glucose analogue induces a powerful analgesia which adapts following repeated administration. 2-DG analgesia displays significant cross-tolerance with morphine, and like morphine analgesia, is potentiated in hypophysectomized rats. The present study examined further the role of opiates in 2-DG analgesia by examining whether the opiate antagonist, naloxone, would affect 2-DG analgesia, and whether ineffective doses of 2-DG and morphine would interact in a synergistic fashion to induce analgesia. Nociceptive thresholds were measured by the flinch-jump test. Naloxone doses of 1, 5, 10 and 20 mg/kg were all ineffective in reducing significantly 2-DG (600 mg/kg) induced pain threshold elevations. Naloxone failed to attenuate 2-DG (350 mg/kg) analgesia whether administered before or after the 2-DG injection. On the other hand, simultaneous administration of sub-analgesic doses of 2-DG (200 mg/kg) and morphine (2.5 mg/kg) summated to produce significant analgesia. This, 2-DG analgesia is similar to opiates in its tolerant and summative actions, yet dissimilar in that naloxone is ineffective in reversing its effects.