Possible involvement of presynaptic 5-HT autoreceptors in effect of lithium on 5-HT release in hippocampus of rat.
The effects of subacute treatment with lithium on the stimulation-induced release of serotonin (5-HT) and the function of 5-HT autoreceptors in the hippocampus and frontal cortex of the rat were studied. In the rats treated with lithium for 3 days, the high K+-evoked release of endogenous 5-HT from the slices of hippocampus, but not the slices of frontal cortex, was significantly increased. High K+-induced release of [3H]5-HT from the slices of hippocampus of control rats preloaded with [3H]5-HT was decreased when the slices were exposed to 5-HT, while it was increased when they were exposed to methiothepin. In the slices of hippocampus from the lithium-treated rats, this inhibitory effect of 5-HT on the release of [3H]5-HT, evoked by either high K+ or electrical stimulation was significantly attenuated. On the other hand, it was not modified in the slices of frontal cortex. The results suggest that lithium may inhibit the function of 5-HT autoreceptors to regulate the release of 5-HT. This action may, in part, trigger the development of the down-regulation of 5-HT1 receptors occurring in the hippocampus but not in the frontal cortex after chronic treatment with lithium.
Hotta
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I
Department of Psychiatry and Neuroscience, Kure National Hospital, Hiroshima, Japan.
Yamawaki
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S
D000818:Animals; D004558:Electric Stimulation; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008094:Lithium / Q000494:pharmacology*; D008297:Male; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism*
D011985:Receptors, Serotonin; D012701:Serotonin; D008094:Lithium; D011188:Potassium