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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

100%

Zahorodna A., Hess G.

Journal of Physiology and Pharmacology

2006

tom 57

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.

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

100%

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

Journal of Physiology and Pharmacology

2004

tom 55

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.

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

2 Hess G.

2 Zahorodna A.

1 Bobula B.

1 Grzegorzewska M.

1 Tokarski K.

1 2006

1 2004

Wyniki wyszukiwania

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