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NAD(P)H:quinone oxidoreductase 1 (NQO1) is a flavoprotein that utilizes NAD(P)H as an electron donor, catalyzing the two-electron reduction and detoxification of quinones and their derivatives. NQO1؊/؊ mice deficient in NQO1 activity and protein were generated in our laboratory (Rajendirane, V., Joseph, P., Lee, Y. H., Kimura, S., Klein-Szanto, A. J. P., Gonzalez, F. J., and Jaiswal, A. K. (1998) J. Biol. Chem. 273, 7382-7389). Mice lacking a functional NQO1 gene (NQO1؊/؊) were born normal and reproduced adeptly as the wild-type NQO1؉/؉ mice. In the present report, we show that NQO1؊/؊ mice exhibit significantly lower levels of abdominal adipose tissue as compared with the wild-type mice. The NQO1؊/؊ mice showed lower blood levels of glucose, no change in insulin, and higher levels of triglycerides, ␤-hydroxy butyrate, pyruvate, lactate, and glucagon as compared with wild-type mice. Insulin tolerance test demonstrated that the NQO1؊/؊ mice are insulin resistant. The NQO1؊/؊ mice livers also showed significantly higher levels of triglycerides, lactate, pyruvate, and glucose. The liver glycogen reserve was found decreased in NQO1؊/؊ mice as compared with wild-type mice. The livers and kidneys from NQO1؊/؊ mice also showed significantly lower levels of pyridine nucleotides but an increase in the reduced/oxidized NAD(P)H: NAD(P) ratio. These results suggested that loss of NQO1 activity alters the intracellular redox status by increasing the concentration of NAD(P)H. This leads to a reduction in pyridine nucleotide synthesis and reduced glucose and fatty acid metabolism. The alterations in metabolism due to redox changes result in a significant reduction in the amount of abdominal adipose tissue. NAD(P)H:quinone oxidoreductase 1 (NQO1)1 is a 274-amino acid flavoprotein that catalyzes the two-electron reduction and detoxification of quinones and their derivatives (1-3). The cytosolic NQO1 activities, purified from rat liver and human adipose tissue, have been characterized and cloned (1-3).NQO1 utilizes both NADH and NADPH as electron donors (1-3). The two-electron reduction of quinones does not result in the formation of free radicals (semiquinones) and highly reactive oxygen species, hence protecting cells against the adverse effects of quinones and their derivatives (1-3). As a protective agent, NQO1 activity has been shown to prevent the formation of highly reactive quinone metabolites (4), detoxify benzo-(a)pyrene quinone (5), and reduce chromium (VI) toxicity (6). Recently, NQO1 was also shown to reduce benzo(a)pyrene and benzo(a)pyrene quinone induced mutagenicity (7,8).NQO1 activity is present in all tissues but at different levels (1-3). Various investigators have observed large variations in NQO1 activity between individuals, in different tissues from the same individual, and between normal/tumor tissues (1-3). It is generally accepted that tumor tissues and cells of hepatic and colonic origin express higher levels of NQO1, as compared with normal tissues and cells of similar origins (1-3). The normal tissue...

A variety of observations suggest that decreasing glycolysis and increasing levels of reduced glutathione, generated by metabolism of glucose through the pentose phosphate pathway, would have an anticonvulsant effect. Because fructose-1,6-bisphosphate (F1,6BP) shifts the metabolism of glucose from glycolysis to the pentose phosphate pathway, it was hypothesized to have anticonvulsant activity. The anticonvulsant activity of F1,6BP was determined in rat models of acute seizures induced by pilocarpine, kainic acid, or pentylenetetrazole. The efficacy of F1,6BP was compared with that of 2-deoxyglucose (2-DG; an inhibitor of glucose uptake and glycolysis), valproic acid (VPA), and the ketogenic diet. One hour before each convulsant, Sprague Dawley rats received either saline (as seizure controls), F1,6BP (0.25, 0.5 or 1 g/kg), 2-DG (0.25 or 0.5 g/kg), or VPA (0.3 g/kg). Additional animals received the ketogenic diet (starting at 20 or 60 d old). Time to seizure onset, seizure duration, and seizure score were measured in each group. F1,6BP had dose-dependent anticonvulsant activity in all three models, whereas VPA had partial efficacy. 2-DG was only effective in the pilocarpine model. The ketogenic diet had no effect in these models. F1,6BP was also partially effective when given at the first behavioral seizure after pilocarpine. Administration of sodium lactate, which bypasses the block in the glycolytic pathway, abolished the anticonvulsant activity of 2-DG in the pilocarpine model, but only decreased the efficacy of F1,6BP. These data demonstrate that F1,6BP has significant anticonvulsant efficacy.

Synchronized neuronal activity (seizures) can appear in the presence or absence of synaptic transmission. Mechanisms of seizure initiation in each of these conditions have been studied, but relatively few studies have addressed seizure termination. In particular, how are seizures terminated in the absence of synaptic activity where there is no loss of excitatory drive or augmentation of inhibitory inputs? We have studied dynamic activity-dependent changes of intracellular pH in the absence of synaptic transmission using the fluorescent pH indicator carboxylseminaphthorhodafluo-1. During epileptiform activity we observed intracellular acidification, whereas between seizures the intracellular pH recovered. Experimental conditions that shortened the epileptiform discharge correlated with more rapid intracellular acidification. On the other hand, experimental manipulation of intracellular pH altered the duration of the seizure discharge, with acidification resulting in early termination of the epileptiform activity. These data show a direct relationship between the level of intracellular acidification and the duration of the seizures, suggesting that an intracellular pH-dependent process can terminate nonsynaptic neuronal synchronization.