A history of intermittent exposures to drugs of abuse can cause long-term changes in acute behavioural responses to a subsequent drug exposure. In drug-naive rats, morphine can elicit intermittent cataleptic postures followed by sustained increases in locomotor activity. Chronic intermittent morphine treatment can reduce catalepsy and increase locomotor behaviour and stereotypy induced by morph...

OBJECTIVE In this study, we aim to find out the role of microRNA-93-5p (miR-93) and Smad5 in morphine tolerance in mouse models of bone cancer pain (BCP). RESULTS At 7 days after injection of morphine, the PMWT showed no significant difference between the morphine model group and the saline model group (P < 0.05), suggesting that morphine tolerance had formed in the morphine model group. The ...

Spinal NMDA receptor (NMDAR), protein kinase C (PKC), and glucocorticoid receptor (GR) have all been implicated in the mechanisms of morphine tolerance; however, how these cellular elements interact after chronic morphine exposure remains unclear. Here we show that the expression of spinal NMDAR and PKCgamma after chronic morphine is regulated by spinal GR through a cAMP response element-bindin...

BACKGROUND This study was designed to assess the postoperative analgesic effect of low-dose intrathecal morphine after scoliosis surgery in children. METHODS Thirty children, 9-19 yr of age, scheduled for spinal fusion, were randomly allocated into three groups to receive a single dose of 0 (saline injection), 2, or 5 microg/kg intrathecal morphine. After surgery, a patient-controlled analges...

The study aimed to find whether subcutaneous morphine administration by syringe driver for terminally ill patients in a Dutch nursing home led to higher morphine doses and earlier death than routine morphine administration. The data comprised the files of all patients dying over a 2 year period in a 355-bed nursing home in Delft in the Netherlands. Thirty-eight per cent of the patients had been...

Adding morphine to intrathecal bupivacaine provides sound analgesia, but is associated with side effects. The purpose of this study is to investigate if the contribution of intrathecal morphine to postoperative analgesia for total hip replacement outweighs its side effects in a modern multimodal setting. From November 2012 till January 2013 patients undergoing total hip arthroplasty (THA) under...

Rats were subject to daily injections of morphine or saline and were then allowed to spontaneously withdraw from morphine for 4 days. Mean arterial blood pressure (MAP) and heart rate (HR) were recorded continuously, via radiotelemetry, during the development of, and recovery from, opiate dependence. Injections of morphine produced pronounced and prolonged increases in MAP and HR which increase...

Morphine stimulates tumor angiogenesis and cancer progression in mice. We examined if morphine influences endothelial-pericyte interaction via platelet-derived growth factor-BB (PDGF-BB) and PDGF receptor-β (PDGFR-β). Clinically relevant doses of morphine stimulated PDGF-BB secretion from human umbilical vein endothelial cells and activated PDGFR-β and mitogen-activated protein kinase/extracell...

BACKGROUND AND AIM Morphine co-injection has anti-inflammatory effects on zymosan-induced peritonitis in several strains of mice except that of CBA. As peritoneal mast cells (pMCs) are much more numerous in CBA mice than in SWISS mice, therole of pMCs in morphine-modulated zymosan peritonitis is compared in CBA and SWISS males. METHODS pMCs were treated in vitro with morphine or C48/80 for co...

BACKGROUND Morphine induces adaptive changes in gene expression throughout the reward circuitry of the brain. Here, we investigated the acute and chronic effects of morphine on mRNA levels of κ-opioid receptor in the rat mesocorticolimbic system. METHODS Three groups of rats received ip injection of saline, acute morphine (8.0 mg/kg) and repeated morphine (8.0 mg/kg, once daily for 5 consecut...