Behavioural pharmacology
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Behavioural pharmacology · Dec 2001
Comparative StudyReceptor-selective antagonism of opioid antinociception in female versus male rats.
This study was conducted to determine whether sex differences in opioid antinociception may be explained by sex differences in opioid receptor activation. The time course, dose-effect and selectivity of antagonists that have been previously shown to be relatively mu (beta-funaltrexamine, beta-FNA), kappa (norbinaltorphimine, norBNI), or delta (naltrindole, NTI) receptor selective in male animals were compared in female and male Sprague-Dawley rats using a 52 degrees C hotplate test. In both sexes, beta-FNA (10 or 20 microg intracerebroventricularly [i.c.v.]) dose-dependently blocked the antinociceptive effects of fentanyl (0.056 mg/kg subcutaneously); antagonism was observed 24 h after beta-FNA, and diminished within 7-14 days. ⋯ The antinociceptive effect of the delta receptor-preferring agonist SNC 80 was significantly antagonized by NTI, but not by norBNI or beta-FNA, in both sexes. The sex difference in beta-FNA antagonism of morphine suggests that there may be sex differences in functional mu opioid receptor reserve or signal transduction; however, the lack of consistency across all mu agonists weakens this hypothesis. Overall, the opioids tested had very similar receptor selectivity in male and female subjects.
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Behavioural pharmacology · Apr 2012
AMPA glutamate receptors mediate the antidepressant-like effects of N-acetylcysteine in the mouse tail suspension test.
The aim of this study was to investigate the involvement of noradrenaline, serotonin, and subtypes of glutamate receptors in the antidepressant-like effects of N-acetylcysteine (NAC). The tail suspension test was used with male CF1 albino mice. D,L-α-methyl-ρ-tyrosine and ρ-chlorophenylalanine methyl ester hydrochloride were used as synthesis inhibitors of noradrenaline and serotonin, respectively. ⋯ The results point to the key role of AMPA receptors in the mechanism of the antidepressant-like action of NAC. Like other AMPA potentiators, NAC indirectly modulates noradrenaline and serotonin pathways. It is suggested that the value of NAC as an antidepressant arises from combined and intertwined effects on a variety of pathways.
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Behavioural pharmacology · Mar 2010
Socially induced morphine pseudosensitization in adolescent mice.
Given that social influences are among the strongest predictors of adolescents' drug use, this study examined the effect of social interaction on morphine-induced hyperlocomotion in both adolescent and adult mice. Three experimental groups of adolescent and adult male mice were examined (i) morphine-treated mice (twice daily, 10-40 mg/kg, subcutaneous), (ii) saline-injected mice housed together with the morphine-treated mice ('saline cage-mates'), and (iii) saline-injected mice housed physically and visually separated from the morphine-treated mice ('saline alone'). After the treatment period, mice were tested individually for their locomotor response to 10 mg/kg morphine (subcutaneous). ⋯ In adults, there were no significant differences in morphine-induced hyperlocomotion between saline alone and saline cage-mates. As expected, morphine-treated adults and adolescents both exhibited locomotor sensitization. These results show a vulnerability to social influences in adolescent mice, which does not exist in adult mice.
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Behavioural pharmacology · Nov 2003
Comparative StudyFacilitation and disruption of memory for the passive avoidance task in the day-old chick using dopamine D1 receptor compounds.
This series of studies provides a behavioural account of dopamine D1-receptor-dependent facilitation and disruption of memory for the single-trial passive avoidance task in the day-old chick. The D1 antagonist, SCH23390, induced memory disruption in a dose-dependent manner from 60 min after training with a strong (100% methyl anthranilate) aversant experience. ⋯ The D2 antagonist, sulpiride, and the D2 agonist, quinpirole, showed no memory effects. The research indicates an important role for dopamine D1-dependent mechanisms in memory formation in the chick.
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Behavioural pharmacology · Dec 2011
Intrathecal lemnalol, a natural marine compound obtained from Formosan soft coral, attenuates nociceptive responses and the activity of spinal glial cells in neuropathic rats.
The investigators previously found that the administration of lemnalol, a natural marine compound isolated from the Formosan soft coral Lemnalia cervicorni, produced anti-inflammatory and analgesic effects in carrageenan-injected rats. Recently, several studies have demonstrated that the development and maintenance of neuropathic pain are accompanied by releasing of proinflammatory mediators from activated glial cells in the spinal cord. In this study, we investigated the antinociceptive properties of lemnalol, a potential anti-inflammatory compound, on chronic constriction injury (CCI) in a well-established rat model of neuropathic pain. ⋯ Furthermore, immunohistofluorescence analyses showed that lemnalol (10 μg) also significantly inhibits CCI-induced upregulation of microglial and astrocytic immunohistochemical activation markers in the dorsal horn of the lumbar spinal cord. Double immunofluorescent staining demonstrated that intrathecal injection of lemnalol (10 μg) markedly inhibited spinal proinflammatory mediator tumor necrosis factor-α expression in microglial cells and astrocytes in neuropathic rats. Collectively, our results indicate that lemnalol is a potential therapeutic agent for neuropathic pain, and that further exploration of the effects of lemnalol on glial proinflammatory responses is warranted.