Chronic lithium administration to rats selectively modifies 5-HT2A/2C receptor-mediated brain signaling via arachidonic acid.
The effects of chronic lithium administration on regional brain incorporation coefficients k* of arachidonic acid (AA), a marker of phospholipase A2 (PLA2) activation, were determined in unanesthetized rats administered i.p. saline or 1 mg/kg i.p. (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), a 5-HT2A/2C receptor agonist. After injecting [1-(14)C]AA intravenously, k* (brain radioactivity/integrated plasma radioactivity) was measured in each of 94 brain regions by quantitative autoradiography. Studies were performed in rats fed a LiCl or a control diet for 6 weeks. In the control diet rats, DOI significantly increased k* in widespread brain areas containing 5-HT2A/2C receptors. In the LiCl-fed rats, the significant positive k* response to DOI did not differ from that in control diet rats in most brain regions, except in auditory and visual areas, where the response was absent. LiCl did not change the head turning response to DOI seen in control rats. In summary, LiCl feeding blocked PLA2-mediated signal involving AA in response to DOI in visual and auditory regions, but not generally elsewhere. These selective effects may be related to lithium's therapeutic efficacy in patients with bipolar disorder, particularly its ability to ameliorate hallucinations in that disease.
Basselin
Mireille
M
Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA. mirvasln@mail.nih.gov
Chang
Lisa
L
Seemann
Ruth
R
Bell
Jane M
JM
Rapoport
Stanley I
SI
D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D018021:Lithium Chloride / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D044402:Receptor, Serotonin, 5-HT2A / Q000187:drug effects / Q000502:physiology*; D044405:Receptor, Serotonin, 5-HT2C / Q000187:drug effects / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000662:Amphetamines; D044402:Receptor, Serotonin, 5-HT2A; D044405:Receptor, Serotonin, 5-HT2C; D017366:Serotonin Receptor Agonists; D016718:Arachidonic Acid; D018021:Lithium Chloride; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine