The goal of this study was to evaluate the effects of quercetin and ACTH injection on prevention of development of morphine tolerance and dependence in mice. In this study different groups of mice received morphine (40 mg/kg, i.p.) plus quercetin (5, 10, 25 mg/kg, ip), ACTH (1, 2.5, 5 IU/mice, i.p.), or combination of quercetin (5 mg/kg) and ACTH (1 IU/mice) once a day for four days. Toler...

The innate immune system modulates opioid-induced effects within the central nervous system and one target that has received considerable attention is the toll-like receptor 4 (TLR4). Here, we examined the contribution of TLR4 in the development of morphine tolerance, hyperalgesia, and physical dependence in two inbred mouse strains: C3H/HeJ mice which have a dominant negative point mutation in...

with morphine together with subanalgesic doses of a second opiate did not develop tolerance to the morphine even after seven days of treatment. Although morphine is a favored choice for easing pain, a major drawback of its long-term use is the development of tolerance, which results in reduced analgesic effects upon long-term use. Morphine binds the opioid receptor (MOR), one member of the larg...

mu opioid receptors are targets of native opioid peptides and addictive analgesic drugs. A major clinical liability of opiate drugs is their ability to cause physiological tolerance. Individual opiates, such as morphine and etorphine, differ both in their ability to promote physiological tolerance and in their effects on receptor regulation by endocytosis. Here, we demonstrate that arrestins pl...