The present experiments examined the role of spinal proinflammatory cytokines [interleukin-1beta (IL-1)] and chemokines (fractalkine) in acute analgesia and in the development of analgesic tolerance, thermal hyperalgesia, and tactile allodynia in response to chronic intrathecal morphine. Chronic (5 d), but not acute (1 d), intrathecal morphine was associated with a rapid increase in proinflamma...

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...

One reported mechanism for morphine activation of dopamine (DA) neurons of the ventral tegmental area (VTA) is the disinhibition model of VTA-DA neurons. Morphine inhibits GABA inhibitory neurons, which shifts the balance between inhibitory and excitatory input to VTA-DA neurons in favor of excitation and then leads to VTA-DA neuron excitation. However, it is not known whether morphine has an a...

The relationship between postmortem concentrations of morphine and co-detected psychoactive drugs in fatal overdoses is examined. Morphine and other drugs were detected in 161 medicolegal autopsy cases. Subsets of these morphine-positive cases based on drug class were established, including opioids, antidepressants, ethanol, benzodiazepines, and "other." Each subset was split into high or low c...

The blood-brain barrier (BBB) permeability to morphine and morphine-6-glucuronide (M6G) is measured under identical conditions using an intravenous injection method in the rat and HPLC separation of morphine from its metabolites. The brain uptake of M6G expressed as %ID/g was 32-fold lower than that of morphine, and the BBB permeability surface area product (PS) of M6G was 57-fold lower as comp...

background: although opioids suppressive effects on immune system function have been reported, this study demonstrates inflammatory reactions, such as production of pro-inflammatory cytokines and suppression of anti-inflammatory cytokines, are the main causes at organ’s allotransplantation rejection in chronic morphine-treated recipients. methods: 28 rats were categorized in 4groups through int...

Six female adult Macaca mulatta monkeys were made dependent upon morphine sulfate and wermanted with a chronic indwelling needle in the lateral ventricle of the brain for sterile intraventricular injections. Both B-endorphin and morphine, in a dose dependent manner given intraventricularly suppressed the signs of 14 hour acute morphine abstinence. On a molar basis, 8-endorphin was more active t...

Human plasma contains low, but physiologically significant, concentrations of morphine that can increase following trauma or exercise. We now demonstrate that normal, human white blood cells (WBC), specifically polymorphonuclear cells, contain and have the ability to synthesize morphine. We also show that WBC express CYP2D6, an enzyme capable of synthesizing morphine from tyramine, norlaudanoso...

Morphine has been reported to accelerate the progression of chronic kidney disease. However, whether morphine affects slit diaphragm (SD), the major constituent of glomerular filtration barrier, is still unclear. In the present study, we examined the effect of morphine on glomerular filtration barrier in general and podocyte integrity in particular. Mice were administered either normal saline o...

OBJECTIVES Morphine is widely used to treat chronic pain. However, its utility is hindered by the development of tolerance to its analgesic effects. Despite the renowned beneficial effects of physical exercise on cognitive functions and signs of morphine withdrawal in morphine-dependent rats, little is known about the roles of voluntary and forced exercises in tolerance to analgesic effect of m...