Abstract
Whereas antibipolar drug administration to rats reduces brain arachidonic acid turnover, excessive N-methyl-d-aspartate (NMDA) signaling is thought to contribute to bipolar disorder symptoms and may increase arachidonic acid turnover in rat brain phospholipids. To determine whether chronic NMDA would increase brain arachidonic acid turnover, rats were daily administered NMDA (25 mg/kg, ip) or vehicle for 21 days. In unanesthetized rats, on day 21, [1-(14)C]arachidonic acid was infused intravenously and arterial blood plasma was sampled until the animal was euthanized at 5 min and its microwaved brain was subjected to chemical and radiotracer analysis. Using equations from our in vivo fatty acid model, we found that compared with controls, chronic NMDA increased the net rate of incorporation of plasma unesterified arachidonic acid into brain phospholipids (25-34%) as well as the turnover of arachidonic acid within brain phospholipids (35-58%). These changes were absent at 3 h after a single NMDA injection. The changes, opposite to those after chronic administration of antimanic drugs to rats, suggest that excessive NMDA signaling via arachidonic acid may be a model of upregulated arachidonic acid turnover in brain phospholipids.
Highlights
Whereas antibipolar drug administration to rats reduces brain arachidonic acid turnover, excessive Nmethyl-D-aspartate (NMDA) signaling is thought to contribute to bipolar disorder symptoms and may increase arachidonic acid turnover in rat brain phospholipids
Controls received the same volume of vehicle (0.9% saline) once daily for 21 days. We reported that this chronic NMDA dosing regimen increases brain cytosolic phospholipase A2 (cPLA2) activity, protein, and mRNA [33]
Consistent with these findings, chronic but not single NMDA injection increased the net rates of incorporation of arachidonic acid into brain phospholipids from the brain arachidonoyl-CoA pool ( JFA,i) and of arachidonic acid turnover (FFA,i)
Summary
Whereas antibipolar drug administration to rats reduces brain arachidonic acid turnover, excessive Nmethyl-D-aspartate (NMDA) signaling is thought to contribute to bipolar disorder symptoms and may increase arachidonic acid turnover in rat brain phospholipids. Using equations from our in vivo fatty acid model, we found that compared with controls, chronic NMDA increased the net rate of incorporation of plasma unesterified arachidonic acid into brain phospholipids (25– 34%) as well as the turnover of arachidonic acid within brain phospholipids (35–58%) These changes were absent at 3 h after a single NMDA injection. The changes, opposite to those after chronic administration of antimanic drugs to rats, suggest that excessive NMDA signaling via arachidonic acid may be a model of upregulated arachidonic acid turnover in brain phospholipids.—Lee, H-J., J. Arachidonic acid signaling has been implicated in bipolar disorder [27], because chronic antimanic drug administration (lithium, carbamazepine, or valproate) to rats decreases arachidonic acid turnover in their brain phospholipids [28,29,30].
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