Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is a potential remedial therapy for drug craving and relapse, but the mechanism is poorly understood. We investigated changes in neurotransmitter levels during high frequency stimulation (HFS) of the unilateral NAc on morphine-induced rats. Sixty adult Wistar rats were randomized into five groups: the control group (administration of s...

Glycyl-glutamine (Gly-Gln; beta-endorphin(30-31)) is an endogenous dipeptide synthesized from beta-endorphin(1-31). Previous investigations have shown that Gly-Gln inhibits the cardiovascular and respiratory depression caused by morphine and beta-endorphin(1-31), but it does not interfere with opioid analgesia. In this study, we tested whether Gly-Gln administration would influence morphine-ind...

Morphine, morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G), and 6-monoacetylmorphine (6-MAM) were isolated from body fluids using solid-phase extraction and determined by means of atmospheric pressure chemical ionization-mass spectrometry-liquid chromatography (APCI-LC-MS) in selected ion monitoring mode. The following ions were monitored: m/z 286 for morphine; m/z 286 and 462 for M3G...

BACKGROUND After cardiac surgery adequate postoperative analgesia is necessary. We assessed analgesia using intrathecal morphine and clonidine. METHODS In a double-blind randomized study, 45 patients having coronary artery bypass graft surgery were allocated randomly to receive i.v. patient-controlled analgesia (PCA) morphine (bolus, 1 mg; lock-out interval, 7 min) (control group), either alo...

When rats are forced to drink a morphine solution as their only source of fluid, they eventually reverse their initial preference and drink more morphine than water in a two-bottle preference test. The cause of this shift in preference was examined with the taste reactivity test which involves the analysis of fixed action patterns elicited by taste solutions infused into rats' mouths. Three mor...

The effect of naloxone given at various times after morphine administration on the development of tolerance to and dependence on a single dose of morphine was studied. Naloxone antagonized the analgesic effect of morphine and the development of tolerance to and dependence on morphine, dose dependently. The time course of the development of tolerance to a single dose of morphine almost parallele...

After epidural administration of 15 mg 3, 6-dinicotinoylmorphine (nicomorphine) in 10 patients undergoing pulmonary surgery, the parent compound was quickly metabolized into the metabolites 6-mononicotinoylmorphine and morphine. The mean apparent half-lives (+/- SD) of elimination were 10 min (0.165 h +/- 0.053 h) for 3,6-dinicotinoylmorphine and 1.77 h +/- 1.23 h for 6-mononicotinoylmorphine. ...

The bioavailability of oral controlled release morphine tablets (MST, Napp Laboratories) and oral morphine sulphate in aqueous solution (MSS) was compared in 10 patients with advanced cancer. Serum samples were analysed for morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) using a specific HPLC assay. The relative bioavailability of morphine with MST was significantly less...

The opponent-process theory posits that the aversive state of acute opiate withdrawal is a consequence of, and depends on, the previous rewarding state evoked by acute morphine reward. Although the brainstem tegmental pedunculopontine nucleus (TPP) is crucial for the rewarding component of morphine, the source of the later aversive component is not known. It is possible that (i) the second aver...

Our previous studies have shown that morphine withdrawal induced an increase in the expression of protein kinase (PK) A and mitogen-activated extracellular kinase (MAPK) pathways in the heart during morphine withdrawal. The purpose of the present study was to evaluate the interaction between PKA and extracellular signal-regulated kinase (ERK) signaling pathways mediating the cardiac adaptive ch...