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Psychopharmacology (Berl). 1993;112(1):74-9.

Chronic lithium treatment enhances the postsynaptic 5-HT1A receptor-mediated 5-HT behavioral syndrome induced by 8-OH-DPAT in rats via catecholaminergic systems.

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1
Department of Neurology and Psychiatry, Hiroshima University School of Medicine, Japan.

Abstract

The effects of antimanic agents, including lithium, carbamazepine, clonazepam and zotepine, on the postsynaptic 5-HT1A receptor-mediated behavioral and hypothermic responses induced by 8-OH-DPAT in rats, and on [3H]8-OH-DPAT binding to 5-HT1A receptors in the rat hippocampus were examined. Treatment with lithium (3 mEq/kg, IP) for 14 days enhanced forepaw treading, one component of the 5-HT behavioral syndrome induced by 8-OH-DPAT, and this enhancement by lithium was abolished by catecholamine depletion with reserpine or alpha-methyl-p-tyrosine, but not by 5-HT depletion with p-chlorophenylalanine. These data suggest that lithium enhances 5-HT1A-mediated behavior via catecholaminergic systems. In contrast, chronic lithium treatment did not alter the hypothermic response to 8-OH-DPAT in untreated rats, as well as in rats treated with reserpine. These findings strengthen the suggestion that lithium has no direct influence on the postsynaptic 5-HT1A-mediated response. Other antimanic agents had no effect on either forepaw treading or hypothermia induced by 8-OH-DPAT. Radioligand binding studies using [3H]-8-OH-DPAT demonstrated that chronic lithium treatment, but not other antimanic agents, caused 5-HT1A receptor down-regulation in rat hippocampus. A discrepancy therefore exists between 5-HT1A receptor down-regulation and unaltered 5-HT1A-mediated behavioral and hypothermic responses in catecholamine-depleted rats after chronic lithium treatment.

PMID:
7871012
[Indexed for MEDLINE]
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