introduction: transient receptor potential vanilloid type 1 (trpv1) and protein kinase cγ (pkcγ) are involved in sensitization/desensitization to noxious stimuli. we aimed to examine the gene expression levels of trpv1 and pkcγ in rat lumbosacral cord and midbrain on days 1, 4 and 8 of induction of morphine analgesic tolerance. methods: two groups of male wistar rats received twice daily saline...

objective(s): we aimed to examine association of gene expression of mor1 and glun1 at mrna level in the lumbosacral cord and midbrain with morphine tolerance in male wistar rats. materials and methods: analgesic effects of morphine administrated intraperitoneally at doses of 0.1, 1, 5 and 10 mg/kg were examined using a hot plate test in rats with and without a history of 15 days morphine (10 mg...

Antagonists of the NMDA type of excitatory amino acid (EAA) receptor attenuate or reverse the development of tolerance to the analgesic effects of the mu opioid agonist morphine, the delta-1 opioid agonist DPDPE but not the kappa-1 agonist U50,488H or the kappa-3 agonist naloxone benzoylhydrazone. The role of the AMPA subtype of EAA receptor in analgesic tolerance was examined using LY293558, a...

objective(s):reduction of pharmacological effectiveness or tolerance appears following repeated administration of many analgesic drugs. we investigated tolerance to anti-nociceptive effects of orexin-a, an endogenous potent analgesic peptide using the hot-plate test.materials and methods:orexin-a was microinjected icv (intracerebroventricular) with an interval of 12 hr for 7 continuous days and...

introduction: several researches have reported that stress is able to inhibit the development of morphine tolerance via activating of hypothalamic-pituitary-adrenal (hpa) axis. in the present study we tried to examine the effect of epinephrine, the product of adrenal medulla, on the development of morphine tolerance. methods: analgesic tolerance was induced by intrathecal (i.t.) injection of mo...

Introduction: Morphine is a potent analgesic but its continual use results in analgesic tolerance. Mechanisms of this tolerance remain to be clarified. However, changes in the functions of μ-opioid and N-Methyl-D-aspartate (NMDA) receptors have been proposed in morphine tolerance. We examined changes in gene expression of the NMDA receptor subunit 1 (NR1) at mRNA levels i...

Objective(s):Reduction of pharmacological effectiveness or tolerance appears following repeated administration of many analgesic drugs. We investigated tolerance to anti-nociceptive effects of orexin-A, an endogenous potent analgesic peptide using the hot-plate test.Materials and Methods:Orexin-A was microinjected ICV (intracerebroventricular) with an interval of 12 hr for 7 continuous days and...

Introduction: Several researches have reported that stress is able to inhibit the development of morphine tolerance via activating of Hypothalamic-Pituitary-Adrenal (HPA) axis. In the present study we tried to examine the effect of epinephrine, the product of adrenal medulla, on the development of morphine tolerance. Methods: Analgesic tolerance was induced by intrathecal (i.t.) injection of...

previous studies have shown that the extract of papaver rhoeas reduces morphine dependence, locomotor activity and reward. in present study, the effects of hydro-alcohol extract of papaver rhoeas on the tolerance to analgesic effects of morphine in mice have been investigated using tail flick method. subcutaneous (s.c.) administration of morphine (1, 2, 5 and 10 mg/kg) induced analgesia. howeve...