Progress in neuro-psychopharmacology & biological psychiatry
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Aug 2012
A novel trigeminal neuropathic pain model: compression of the trigeminal nerve root produces prolonged nociception in rats.
We demonstrate the establishment of a novel animal model for trigeminal neuropathic pain following compression of the trigeminal nerve root, which produces prolonged nociceptive behavior and demyelination of the trigeminal nerve root. Under anesthesia, male Sprague-Dawley rats (200-230 g) were mounted onto a stereotaxic frame and injections of a 4% agar solution (10 μl) were given to achieve compression of the trigeminal nerve root. A sham operation was performed using identical procedures but without agar injections. ⋯ In the medullary dorsal horn, phospho-p38 (p-p38) mitogen-activated protein kinase (MAPK) was found to be exclusively expressed in the microglia on POD 14. Furthermore, intraperitoneal administration of carbamazepine (50mg/kg) significantly blocked mechanical allodynia and reduced p38 MAPK activation induced by the compression of the trigeminal nerve root. Our findings suggest that prolonged nociceptive behavior following compression of the trigeminal nerve root may mimic trigeminal neuralgia in this animal model and that the activation of p38 MAPK in the microglia contributes to pain hypersensitivity in rats that have undergone compression of the trigeminal nerve root.
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Aug 2012
Tobacco smoking produces greater striatal dopamine release in G-allele carriers with mu opioid receptor A118G polymorphism.
To determine if carriers of the allelic expression of the G variant of the human mu opioid receptor (OPRM1) A118G polymorphism have greater increases in striatal dopamine (DA) release after tobacco smoking. ⋯ This preliminary study indicates a difference in both brain striatal DA release and plasma cortisol in A118G polymorphic male tobacco smokers.
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Aug 2012
The anxiolytic-like effect of an essential oil derived from Spiranthera odoratissima A. St. Hil. leaves and its major component, β-caryophyllene, in male mice.
Spiranthera odoratissima A. St. Hil. (manacá) is used in folk medicine to treat renal and hepatic diseases, stomachache, headaches and rheumatism. ⋯ The anxiolytic-like effects of β-caryophyllene were not blocked by either NAN-190 or flumazenil (P>0.05). In conclusion, these results suggest that the essential oil derived from S. odoratissima produces an anxiolytic-like effect without altering motor performance and that this effect is mediated by 5-HT(1A) but not via benzodiazepine receptors. In addition, the major component, β-caryophyllene, also has an anxiolytic-like effect that may contribute to the effects of EO, but this effect does not seem to be mediated via 5-HT(1A) or benzodiazepine receptors.
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Jul 2012
ReviewEffects induced by cannabinoids on monoaminergic systems in the brain and their implications for psychiatric disorders.
The endocannabinoid system and CB(1) receptors participate in the control of emotional behavior and mood through a functional coupling with the classic monoaminergic systems. In general, the acute stimulation of CB(1) receptors increases the activity (spontaneous firing rate) of noradrenergic (NE), serotonergic (5-HT) and dopaminergic (DA) neurons as well as the synthesis and/or release of the corresponding neurotransmitter in specific brain regions. Notably, the antagonist/inverse agonist rimonabant (SR141617A) can decrease the basal activity of NE and 5-HT neurons, suggesting a tonic/constitutive regulation of these neuronal systems by endocannabinoids acting at CB(1) receptors. ⋯ CB(1) receptor desensitization may alter the direct and/or indirect effects of cannabinoid drugs modulating the functionality of monoaminergic systems. The sustained activation of monoaminergic neurons by cannabinoid drugs can also be related to changes in the function of presynaptic inhibitory α(2)-adrenoceptors or 5-HT(1A) receptors (autoreceptors and heteroreceptors), whose sensitivity is downregulated or upregulated upon chronic CB(1) agonist exposure. The functional interactions between endocannabinoids and monoaminergic systems in the brain indicate a potential role for CB(1) receptor signaling in the neurobiology of various psychiatric disorders, including major depression and schizophrenia as the major syndromes.
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Jul 2012
ReviewInvolvement of descending serotonergic and noradrenergic pathways in CB1 receptor-mediated antinociception.
Cannabinoids produce antinociceptive and antihyperalgesic effects mainly through activation of the inhibitory CB1 receptors. The demonstration that antinociceptive effects of systemic cannabinoids are significantly diminished following surgical dorsolateral funiculus lesion provides evidence that supraspinal sites and descending pain modulatory pathways play crucial roles in systemic cannabinoid analgesia. ⋯ We will then describe the recent evidence of the involvement of descending serotonergic and noradrenergic pathways in CB1 receptor-mediated antinociception. This review will provide evidences that systemically administered cannabinoids reinforce the descending serotonergic and noradrenergic pathways to produce acute antinociceptive effects via spinal 5-HT7, 5-HT2A and alpha-2 adrenoceptors activation.