Chronic carbamazepine selectively downregulates cytosolic phospholipase A2 expression and cyclooxygenase activity in rat brain.
BACKGROUND
Carbamazepine is a mood stabilizer used as monotherapy or as an adjunct to lithium in the treatment of acute mania or the prophylaxis of bipolar disorder. Based on evidence that lithium and valproate, other mood stabilizers, reduce brain arachidonic acid turnover and its conversion via cyclooxygenase to prostaglandin E(2) in rat brain, one possibility is that carbamazepine also targets the arachidonic acid cascade.


METHODS
To test this hypothesis, carbamazepine was administered to rats by intraperitoneal injection at a daily dose of 25 mg/kg for 30 days.


RESULTS
Carbamazepine decreased brain phospholipase A(2) activity and cytosolic phospholipase A(2) protein and messenger RNA levels without changing significantly protein and activity levels of calcium-independent phospholipase A(2) or secretory phospholipase A(2). Cyclooxygenase activity was decreased in carbamazepine-treated rats without any change in cyclooxygenase-1 or cyclooxygenase-2 protein levels. Brain prostaglandin E(2) concentration also was reduced. The protein levels of other arachidonic acid metabolizing enzymes, 5-lipoxygenase and cytochrome P450 epoxygenase, were not significantly changed nor was the brain concentration of the 5-lipoxygenase product leukotriene B(4).


CONCLUSIONS
Carbamazepine downregulates cytosolic phospholipase A(2)-mediated release of arachidonic acid and its subsequent conversion to prostaglandin E(2) by cyclooxygenase. These effects may contribute to its therapeutic actions in bipolar disorder.
Ghelardoni
Sandra
S
Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA.
Tomita
York A
YA
Bell
Jane M
JM
Rapoport
Stanley I
SI
Bosetti
Francesca
F
D018712:Analgesics, Non-Narcotic / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D001923:Brain Chemistry / Q000187:drug effects; D002220:Carbamazepine / Q000097:blood / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D015536:Down-Regulation / Q000187:drug effects; D015777:Eicosanoids / Q000378:metabolism; D008297:Male; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011916:Rats, Inbred F344; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D018712:Analgesics, Non-Narcotic; D015777:Eicosanoids; D012333:RNA, Messenger; D002220:Carbamazepine; D011451:Prostaglandin-Endoperoxide Synthases; D010741:Phospholipases A; D054467:Phospholipases A2