Decreased basal endogenous opioid levels in diabetic rodents: effects on morphine and delta-9-tetrahydrocannabinoid-induced antinociception.
We have previously demonstrated synergy between morphine and Delta(9)-tetrahydrocannabinol (Delta(9)-THC) in the expression of antinociception in acute pain models and in arthritic models of chronic pain. Our data has been extended to include acute pain in both diabetic mice and rats. In diabetic mice, Delta(9)-THC p.o. was more active in the tail-flick test in the diabetic mouse than in the non-diabetic mouse. Morphine (s.c.) was less potent in diabetic than in non-diabetic mice [6.1 (5.1-7.2) versus 3.2 (2.4-4.1) mg/kg, respectively], an effect previously extensively documented in pre-clinical and clinical testing. In addition, the combination of Delta(9)-THC with morphine produced a greater-than-additive relief of acute pain in mice. In the rat, the induction of the diabetic state decreased the antinociceptive effect of morphine, an effect temporally related to a decreased release of specific endogenous opioids. Conversely, Delta(9)-THC retained the ability to release endogenous opioids in diabetic rats and maintained significant antinociception. Extrapolation of such studies to the clinical setting may indicate the potential for use of Delta(9)-THC-like drugs in the treatment of diabetic neuropathic pain, alone or in combination with very low doses of opioids.
Williams
Jovan
J
Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298-0524, USA.
Haller
Victoria L
VL
Stevens
David L
DL
Welch
Sandra P
SP
D000284:Administration, Oral; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000494:pharmacology*; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology*; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D018847:Opioid Peptides / Q000378:metabolism*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D018847:Opioid Peptides; D009020:Morphine; D013759:Dronabinol