Wyniki wyszukiwania

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Imipramine and citalopram reverse corticosterone-induced alterations in the effects of the activation of 5-HT1A and 5-HT2 receptors in rat frontal cortex

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Zahorodna A., Hess G.

Journal of Physiology and Pharmacology

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2006

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tom 57

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nr 3

Using extracellular recording we studied changes in the reactivity of rat frontal cortical slices to the 5-HT1A, 5-HT2 and 5-HT4 receptor agonists, (±)-2-dipropyloamino-8-hydroxy-1,2,3,4-tetrahydronaphtalene hydrobromide (8-OH-DPAT), (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and zacopride, respectively, induced by an earlier treatment of animals with corticosterone lasting 1 or 3 weeks. Spontaneous bursting activity was recorded in ex vivo slices incubated in a medium devoid of Mg2+ ions and containing picrotoxin (30 µM). Repetitive, but not single, corticosterone administration resulted in an attenuation of the effect of the activation of 5-HT1A receptors and in an enhancement of the effect related to 5-HT2 receptors. The effect of 5-HT4 receptor activation remained unchanged. In separate two sets of experiments rats were treated with corticosterone for 3 weeks and additionally with imipramine or citalopram, beginning on the eighth day of corticosterone administration. In the corticosterone plus imipramine as well as corticosterone plus citalopram groups the effects of 8-OH-DPAT and DOI were not different from control indicating that corticosterone-induced functional modifications in the reactivity of 5-HT1A and 5-HT2 receptors were reversed by antidepressant treatments.

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The influence of repeated administration of clozapine and haloperidol on the effects of the activation of 5-HT1A, 5-HT2 and 5-HT4 receptors in rat frontal cortex

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Zahorodna A., Bobula B., Grzegorzewska M., Tokarski K., Hess G.

Journal of Physiology and Pharmacology

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2004

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tom 55

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nr 2

The effects of a repeated treatment with antipsychotic drugs, clozapine and haloperidol, on the modulation of network activity ex vivo by 5-HT receptors were examined in rat frontal cortical slices using extracellular recording. Rats were treated for 21 days with clozapine (30 mg/kg p.o.), or haloperidol (1 mg/kg p.o.). Spontaneous bursting activity was induced in slices prepared 3 days after the last drug administration by perfusion with a medium devoid of Mg2+ ions and with added picrotoxin (30 mM). The application of 2-3 µM 8-OH-DPAT, acting through 5-HT1A receptors, resulted in a reversible decrease of bursting frequency. In the presence of 1 µM DOI, the 5-HT2 agonist, or 5 µM zacopride, the 5-HT4 agonist, bursting frequency increased. Chronic clozapine treatment resulted in an attenuation of the effect of the activation of 5-HT2 receptors, while the effects related to 5-HT1A and 5-HT4 receptor activation were unchanged. Treatment with haloperidol did not influence the reactivity to the activation of any of the three 5-HT receptor subtypes. These data are consistent with earlier findings demonstrating a selective downregulation of 5-HT2A receptors by clozapine and indicate that chronic clozapine selectively attenuates the 5-HT-mediated excitation in neuronal circuitry of the frontal cortex while leaving the 5-HT-mediated inhibition intact.

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DOI, an agonist of 5-HT2A-2C serotonin receptor, alters the expression of cyclooxygenase-2 in the rat parietal cortex

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Mackowiak M., Chocyk A., Sanak M., Czyrak A., Fijal K., Wedzony K.

Journal of Physiology and Pharmacology

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2002

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tom 53

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nr 3

The hallucinogenic effect of DOI, serotonin 5-HT2A/2C receptor agonist, is known to be associated with the activation of cortical 5-HT2 receptors. However, the effect of DOI on excitability of cortical neurons and their subsequent function is still not quite understood. Previous immunohistochemical studies using Fos proteins expression as a marker of neuronal activity showed the involvement of arachidonic acid cascade, particularly cyclooxygenase metabolic pathway, in DOI-induced Fos proteins expression in the rat parietal cortex. DOI increases arachidonic acid release which is transformed itself via acceleration of cyclooxygenase metabolic pathway to biologically active metabolites, such as prostaglandins and tromboxanes. Since cyclooxygenase-2 (COX-2) expression correlates with neuronal activity, it was of interest to investigate whether DOI is capable of influencing the level of COX-2 protein and mRNA expression in the rat parietal cortex. It was observed that neurons which were positive for 5-HT2A receptors showed constitutive COX-2 immunoreactivity. It was found further, that COX-2 protein level was increased at 1h, and returned to the control level at 3 and 6 h after DOI (5 mg/kg) administration. In contrast, DOI decreased the COX-2 mRNA expression at all tested time points (1h, 3h and 6h after DOI treatment). The obtained results further support the suggestion that COX-2 activation and possibly arachidonic acid metabolites generated by COX-2 may be considered as important mediators of functional responses generated by activation of cortical 5-HT2A/2C receptors.

Ograniczanie wyników

3 Journal of Physiology and Pharmacology

2 Hess G.

2 Zahorodna A.

1 Bobula B.

1 Chocyk A.

1 Czyrak A.

1 Fijal K.

1 Grzegorzewska M.

1 Mackowiak M.

1 Sanak M.

1 Tokarski K.

1 Wedzony K.

1 2006

1 2004

1 2002

Imipramine and citalopram reverse corticosterone-induced alterations in the effects of the activation of 5-HT1A and 5-HT2 receptors in rat frontal cortex

The influence of repeated administration of clozapine and haloperidol on the effects of the activation of 5-HT1A, 5-HT2 and 5-HT4 receptors in rat frontal cortex

DOI, an agonist of 5-HT2A-2C serotonin receptor, alters the expression of cyclooxygenase-2 in the rat parietal cortex