Differential effects of repeated imipramine on hippocampal responsiveness to adenosine and serotonin.
Imipramine-induced enhancement of the inhibitory action of 5-HT(lA) receptor activation in hippocampal pyramidal neurons has been attributed to alterations in the transduction mechanism that involves G protein-dependent opening of K(+) channels. Postsynaptic 5-HT(lA) and adenosine Al receptors may share that transduction pathway. We investigated the influence of repeated imipramine administration on 5-HT(lA) and adenosine A1 receptor-mediated effects in rat hippocampal slices. Repeated imipramine selectively enhanced the postsynaptic effects of 5-HT(1A) receptor activation, including hyperpolarization and reduction of input resistance of neurons and reduction of the population spike amplitude. In contrast, after imipramine treatment only the presynaptic effect of adenosine receptor agonists, a decrease of the field excitatory postsynaptic potential, was enhanced. The data demonstrate that alterations in the presumed common transduction mechanism that was postulated for the 5-HT(lA) and adenosine A1 receptor-mediated activation of K(+) channels are not involved in the effect of repeated imipramine administration.
Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343 Kraków, Poland.
Agnieszka
A
Zahorodna
Maria
M
Bijak
Grzegorz
G
Hess
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology*; D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology*; D000818:Animals; D004334:Drug Administration Schedule; D004347:Drug Interactions; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D007099:Imipramine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D018759:Adrenergic Uptake Inhibitors; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000241:Adenosine; D007099:Imipramine