The relationship between the brain monoaminergic mechanism and morphine tolerance was examined in reserpinized mice. In parallel with the reduction of brain monoamine content, the analgesic effect of morphine was reduced in reserpinized animals. At the peak of the reserpine effect, 24 hr after a single dose of 2.5 mg/kg reserpine, i.p., the analgesic effect of morphine was lowered to about 45% ...

PURPOSE To compare the postoperative analgesic effects of lidocaine, morphine and lidocaine plus morphine administered by constant rate infusion (CRI) and analyzing their effects on opioid requirements after orthopedic surgery in dogs. METHODS Twenty-four dogs underwent fracture repairs were premedicated with IM acepromazine (0.05 mg/kg) combined with morphine (0.3mg/kg). Anesthesia was induc...

In contrast to the rapid development of tolerance to morphine in CD-1 mice, tolerance is not seen in 129/SvEv mice implanted with morphine pellets or given daily morphine injections for 5 days. Similarly, the progressive and complete loss of analgesia in CD-1 mice seen with repeated dosing of the delta ligand [D-Pen2, D-Pen5]enkephalin is not observed in 129/SvEv mice. In contrast, tolerance de...

Spinal intrathecal injections of the nonsteroidal antiinflammatory analgesics (NSAIAs) indomethacin and acetylsalicylic acid, which inhibit prostaglandin synthesis, cause dose-dependent hypoalgesia in the rat. Intrathecal injections of prostaglandin-E2 (PGE2) produce dose-dependent hyperalgesia. To determine whether this action of prostaglandins on the central nervous system is mediated through...

introduction: regulators of g-protein signaling protein negatively control g protein -coupled receptor signaling duration by accelerating gα subunit guanosine triphosphate hydrolysis. since regulator of g-protein signaling4 has an important role in modulating morphine effects at the cellular level and the exact mechanism(s) of adrenalectomy-induced morphine sensitization have not been fully cla...

OBJECTIVE Intrathecal (IT) morphine improves pain control and decreases opioid requirements in children following thoracic and abdominal surgery. However, studies in children report variable durations of analgesia following IT morphine. The purpose of this study is to describe the duration of analgesia in children undergoing surgical correction of idiopathic scoliosis. DESIGN Retrospective ch...

Placenta ingestion has recently been shown to enhance opiate-mediated analgesia produced by morphine injection, footshock, or vaginal/cervical stimulation. The enhancement of the effect of endogenous opiates (especially analgesia) may be one of the principal benefits to mammalian mothers of placentophagia at delivery. During labor and delivery, however, mothers also ingest amniotic fluid (AF) w...

Opioids provide powerful analgesia but also efficacy-limiting adverse effects, including severe nausea, vomiting, and respiratory depression, by activating l-opioid receptors. Preclinical models suggest that differential activation of signaling pathways downstream of these receptors dissociates analgesia from adverse effects; however, this has not yet translated to a treatment with an improved ...

BACKGROUND AND OBJECTIVES The association of drugs with different mechanisms of action in the dorsal horn of the spinal cord decreases postoperative pain, with a reduction in the incidence of side effects. The aim of this study was to evaluate postoperative analgesia and sedation by epidural S(+) ketamine and S(+) ketamine-morphine associated with ropivacaine in subcostal cholecystectomy. MET...

Intrathecal (i.t.) pretreatment with a low dose (0.3 nmol) of morphine causes an attenuation of i.t. morphine-produced analgesia; the phenomenon has been defined as morphine-induced antianalgesia. The opioid-produced analgesia was measured with the tail-flick (TF) test in male CD-1 mice. Intrathecal pretreatment with low dose (0.3 nmol) of morphine time dependently attenuated i.t. morphine-prod...