Opioid and non-opioid effects of acute and chronic morphine administration on behaviour, cardiovascular responses, cell proliferation and apoptosis and nitric-oxide synthase (NOS) activity were studied in rats. A novel score-point scale was introduced to quantify the signs of opioid withdrawal syndrome. NOS inhibitor L-NAME (NG-nitro-L-arginine methyl ester) was applied to reveal the role of NO...

The effects of aqueous and ethanolic leaf extracts of Mentha Longifolia on morphine dependence were examined in mice. Dependence was induced using subcutaneous injections of morphine daily for 3 days. On day 4, the last dose of morphine was injected 2 h perior the intraperitoneal injection of naloxone. The number of episods of jumping during 30 minutes after injection of naloxane was considered...

Our investigation was aimed at elucidating if the chronic administration and withdrawal of a preferential mu-agonist, morphine, induce changes on the heart catecholaminergic neuronal activity. With this purpose the effects of morphine or naloxone (preferentially mu-antagonist) on noradrenaline, adrenaline or dopamine (DA) content and the mechanical response of the left atria were studied in chr...

Stress induces the release of the peptide corticotropin-releasing factor (CRF) into the ventral tegmental area (VTA), and also increases dopamine (DA) levels in brain regions receiving dense VTA input. Since the role of stress in drug addiction is well established, the present study examined the possible involvement of CRF1 receptor in the interaction between morphine withdrawal and catecholami...

Chronic opioid exposure induces neuroadaptative changes in several brain systems. Amongst others the alpha adrenergic system appears to be extremely sensitive to opioid exposure and has, therefore, been proposed to play a key role in opiate withdrawal symptoms. In order to better understand the influence of the noradrenergic system in opioid withdrawal and be able to develop new therapeutic str...

The present study was designed to explore the relationship between the cannabinoid and opioid receptors in animal models of opioid-induced reinforcement. The acute administration of SR141716A, a selective central cannabinoid CB1 receptor antagonist, blocked heroin self-administration in rats, as well as morphine-induced place preference and morphine self-administration in mice. Morphine-depende...

Several lines of evidence suggest a crucial involvement of glutamate in the mechanism of drug addiction. The involvement of group I mGlu receptors in the mechanism of addiction has also been proposed. Given the recent discovery of selective and brain penetrable mGlu5 receptor antagonists, the effects of 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP) were evaluated in the naloxone-precip...

The expression of mRNAs for the glial glutamate transporters, GLT-1 and GLAST, in the rat brain accompanied with morphine dependence and naloxone-precipitated withdrawal was investigated by Northern blot analysis. The expression of GLT-1 mRNA was significantly decreased in the striatum and thalamus of morphine-dependent rats, and significantly increased in the striatum 2 h after the naloxone-pr...

In rhesus monkeys, acute administration of levonantradol and nantradol produced signs of CNS depression, including ataxia with body sag, pupil dilation, ptosis, dozing, and reduced responsivity to external stimuli. Neither compound suppressed the morphine withdrawal syndrome; however, both alleviated the chronic abdominal contraction associated with withdrawal. The directly observable effects o...

Some studies have shown that Matricaria recutita (M. recutita) have sedative effect on pain, anxiety and morphine withdrawal syndrome (MWS). Since some investigations have indicated the sedative effects of benzodiazepines in MWS, so the inhibitory factor of M. recutita may be related to some of its benzodiazepine-like components. In this study sedative properties of M. recutita in the presence ...