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Synergy between delta9-tetrahydrocannabinol and morphine in the arthritic rat.
Eur J Pharmacol 2007; 567(1-2):125-30EJ

Abstract

We have shown in past isobolographic studies that a small amount of Delta(9)-tetrahydrocannabinol (Delta(9)-THC) can enhance morphine antinociception in mice. However, previous studies of the Delta(9)-THC/morphine interaction were performed using normal mice or rats and evaluated acute thermal antinociception. Less is known about cannabinoid and opioid interactions involved in mechanical nociception and in chronic inflammatory pain models, such as Freund's complete adjuvant-induced arthritic model. One fixed-ratio combination was chosen for testing the interaction between Delta(9)-THC and morphine in the Freund's adjuvant-induced arthritic model. This combination represented a 1:1 ratio of the drugs and thus consisted of equieffective doses ranging from 0.1 to 5 mg/kg Delta(9)-THC and from 0.1 to 5 mg/kg morphine. The combination ED(50) value for the fixed ratios (total dose) in relation to the ED(50) value of the drugs alone was determined. The isobolographic analysis indicated a synergistic interaction between Delta(9)-THC and morphine in both the non-arthritic and the arthritic rats. Since Freund's adjuvant-induced alteration in endogenous opioid tone has been previously shown, our data indicate that such changes did not preclude the use of Delta(9)-THC and morphine in combination. As with acute preclinical pain models in which the Delta(9)-THC/morphine combination results in less tolerance development, the implication of the study for chronic pain conditions is discussed.

Authors+Show Affiliations

Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298-0524, United States.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

17498686

Citation

Cox, Melinda L., et al. "Synergy Between Delta9-tetrahydrocannabinol and Morphine in the Arthritic Rat." European Journal of Pharmacology, vol. 567, no. 1-2, 2007, pp. 125-30.
Cox ML, Haller VL, Welch SP. Synergy between delta9-tetrahydrocannabinol and morphine in the arthritic rat. Eur J Pharmacol. 2007;567(1-2):125-30.
Cox, M. L., Haller, V. L., & Welch, S. P. (2007). Synergy between delta9-tetrahydrocannabinol and morphine in the arthritic rat. European Journal of Pharmacology, 567(1-2), pp. 125-30.
Cox ML, Haller VL, Welch SP. Synergy Between Delta9-tetrahydrocannabinol and Morphine in the Arthritic Rat. Eur J Pharmacol. 2007 Jul 12;567(1-2):125-30. PubMed PMID: 17498686.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Synergy between delta9-tetrahydrocannabinol and morphine in the arthritic rat. AU - Cox,Melinda L, AU - Haller,Victoria L, AU - Welch,Sandra P, Y1 - 2007/04/20/ PY - 2007/02/08/received PY - 2007/03/27/revised PY - 2007/04/01/accepted PY - 2007/5/15/pubmed PY - 2007/7/28/medline PY - 2007/5/15/entrez SP - 125 EP - 30 JF - European journal of pharmacology JO - Eur. J. Pharmacol. VL - 567 IS - 1-2 N2 - We have shown in past isobolographic studies that a small amount of Delta(9)-tetrahydrocannabinol (Delta(9)-THC) can enhance morphine antinociception in mice. However, previous studies of the Delta(9)-THC/morphine interaction were performed using normal mice or rats and evaluated acute thermal antinociception. Less is known about cannabinoid and opioid interactions involved in mechanical nociception and in chronic inflammatory pain models, such as Freund's complete adjuvant-induced arthritic model. One fixed-ratio combination was chosen for testing the interaction between Delta(9)-THC and morphine in the Freund's adjuvant-induced arthritic model. This combination represented a 1:1 ratio of the drugs and thus consisted of equieffective doses ranging from 0.1 to 5 mg/kg Delta(9)-THC and from 0.1 to 5 mg/kg morphine. The combination ED(50) value for the fixed ratios (total dose) in relation to the ED(50) value of the drugs alone was determined. The isobolographic analysis indicated a synergistic interaction between Delta(9)-THC and morphine in both the non-arthritic and the arthritic rats. Since Freund's adjuvant-induced alteration in endogenous opioid tone has been previously shown, our data indicate that such changes did not preclude the use of Delta(9)-THC and morphine in combination. As with acute preclinical pain models in which the Delta(9)-THC/morphine combination results in less tolerance development, the implication of the study for chronic pain conditions is discussed. SN - 0014-2999 UR - https://www.unboundmedicine.com/medline/citation/17498686/abstract/Synergy_between_Delta_9__tet DB - PRIME DP - Unbound Medicine ER -