Aims/hypothesis Pyruvate carboxylase (PC) or pyruvate dehydrogenase (PDH) is required to transfer carbons from pyruvate into the Krebs cycle. PC activity is preserved in the islets of obese animals, but it is reduced in the islets of animal models of type 2 diabetes, suggesting that PC is important in beta cell adaptation to insulin resistance and that PC reduction may lead to beta cell failure. Methods To confirm the significance of PC, we first lowered activity using Pc (now known as Pcx) small interfering RNA (siRNA) in INS-1 cells and in dispersed rat islet cells.

Aim/hypothesis: Obesity is a global problem with high risks of cardiovascular diseases, stroke and type 2 diabetes. It is well known that maternal obesity affects offspring by inducing malformation, functional abnormalities in many organs and cells, and by increased risk of obesity and type 2 diabetes. However, little is known about abnormalities induced by maternal obesity in pancreatic beta cells of offspring. Methods: We used mouse mothers with the Agouti yellow modification on a C57BL/6 background as a maternal model of normoglycaemic obesity, and produced Agouti-negative offspring. Half of the offspring were fed a high-fat diet. Offspring glucose tolerance was tested at different ages, and animals were killed at 50 weeks of age for islet function analysis. Results: Maternal obesity impaired glucose tolerance in female offspring fed a high-fat diet, and significantly reduced insulin secretion at 50 weeks of age in female offspring that had been fed a normal diet and high-fat diet. Insulin secretion and glucose potentiation from these islets were significantly reduced. Islet protein, DNA and insulin contents were increased while glyceraldehyde-3-phosphate dehydrogenase and transketolase activities were reduced in female offspring. Conclusions/interpretation: Our results indicate that maternal obesity has a long-term effect on the beta cells of female, but not of male, offspring, and leads to increased risk of gestational diabetes and type 2 diabetes in the offspring's later lives.

It has been shown that maternal diabetes increases the risk for obesity, glucose intolerance, and Type 2 diabetes mellitus in the adult life of the offspring. Mechanisms for these effects on the offspring are not well understood, and little information is available to reveal the mechanisms. We studied the effect of maternal diabetes on ␤-cell function in the offspring of streptozotocin (STZ)-induced diabetic rat mothers (STZ-offspring). STZ-offspring did not become glucose intolerant up to 15 wk of age. At this age, however, insulin secretion was significantly impaired, as measured by in vivo and in vitro studies. Consistent with these changes, islet glucose metabolism and some important glucose metabolic enzyme activities were reduced. No significant changes were found in islet morphological analysis. These data indicate that ␤-cell function is impaired in adult STZ-offspring; these changes may contribute to the development of type 2 diabetes mellitus in adulthood. insulin secretion; islets of Langerhans; type 2 diabetes mellitus EXPERIMENTAL AND CLINICAL STUDIES have shown that the incidence of diabetes is higher in the offspring of diabetic mothers than in offspring of nondiabetic mothers or diabetic fathers (20,35,39,47). Exposure to a diabetic environment in utero is associated with a substantially higher risk of obesity, glucose intolerance, and (non-insulin-dependent) type 2 diabetes mellitus (NIDDM) in the offspring (10,16,32,39,40,44,50). Intrauterine exposure to hyperglycemia is also associated with a higher prevalence of impaired glucose tolerance in adolescence (44) and with an excess of obesity, especially during the first 20 yr of life (10,40,41,45). Systematic prevention of hyperglycemia and impaired glucose tolerance in pregnant women have significantly decreased the prevalence of diabetes mellitus in their children (12). Studies of Pima Indians provide further indication for a role of maternal diabetes in utero: NIDDM is present by age 20 -24 yr in 45.5% of the offspring of diabetic mothers but only in 8.6% and 1.4% of respective offspring of prediabetic or nondiabetic mothers (39). Also in Pima Indians, offspring born after their mothers have developed NIDDM have a 3.7-fold higher risk of developing diabetes than those born before their mother have developed diabetes (11).Animal studies suggest that an adverse influence of maternal diabetes on fetal pancreatic function (4) may contribute to development of NIDDM. Maternal diabetes alters the morphology, number, and size of offspring islets and the ability of the offspring islets to respond to the challenge of pregnancy (5). Insulin secretion has been shown to be abnormal in islets from offspring of diabetic mothers (3). Glucose metabolism is the primary regulator of ␤-cell function (33, 34). However, no studies have examined the changes produced by maternal diabetes on glucose metabolism of offspring islets. In the present study, we have examined ␤-cell insulin secretion and glucose metabolism in the offspring of streptozotocin (STZ)-diabetic mo...

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Microglia are the immune cells of the brain. Hyperactivation of microglia contributes to the pathology of metabolic and neuroinflammatory diseases. Evidence has emerged that links the circadian clock, cellular metabolism, and immune activity in microglia. Rev-erb nuclear receptors are known for their regulatory role in both the molecular clock and cell metabolism, and have recently been found to play an important role in neuroinflammation. The Rev-erbα agonist SR9011 disrupts circadian rhythm by altering intracellular clock machinery. However, the exact role of Rev-erbα in microglial immunometabolism remains to be elucidated. In the current study, we explored whether SR9011 also had such a detrimental impact on microglial immunometabolic functions. Primary microglia were isolated from 1-3 days old Sprague-Dawley rat pups. The expression of clock genes, cytokines and metabolic genes was evaluated using RT-PCR and rhythmic expression was analyzed. Phagocytic activity was determined by the uptake capacity of fluorescent microspheres. Mitochondria function was evaluated by measuring oxygen consumption rate and extracellular acidification rate. We found that key cytokines and metabolic genes are rhythmically expressed in microglia. SR9011 disturbed rhythmic expression of clock genes in microglia. Pro-inflammatory cytokine expression was attenuated by SR9011 during an immune challenge by TNFα, while expression of the anti-inflammatory cytokine Il10 was stimulated. Moreover, SR9011 decreased phagocytic activity, mitochondrial respiration, ATP production, and metabolic gene expression. Our study highlights the link between the intrinsic clock and immunometabolism of microglia. We show that Rev-erbα is implicated in both metabolic homeostasis and the inflammatory responses in microglia, which has important implications for the treatment of metabolic and neuroinflammatory diseases.

Aims/hypothesis The pyruvate-malate shuttle is a metabolic cycle in pancreatic beta cells and is important for beta cell function. Cytosolic malic enzyme (ME) carries out an essential step in the shuttle by converting malate to pyruvate and generating NADPH. In rat islets the pyruvate-malate shuttle may regulate insulin secretion and it has been shown to play a critical role in adaptation to obesity and insulin resistance. However, ME has not been demonstrated in mouse islets and three reports indicate that mouse islets contain no ME activity. If mouse islets lack ME, rat and mouse islets must regulate insulin secretion by different mechanisms. Methods We measured ME activity by a fluorometric enzymatic assay and Me mRNA by real-time PCR. ME activity was also measured in streptozotocin-treated mouse islets. FACS-purified beta cells were obtained from MIP-GFP mouse islets, agouti-L obese mouse islets and mouse beta cell line MIN-6. Insulin secretion and NADPH/ NADP + ratios were measured in Me siRNA-treated beta cells.Results ME activity and Me mRNA were present in C57BL/6 mouse islets. ME activity was reduced in streptozotocintreated mouse islets. ME activity was also measurable in FACS-purified mouse beta cells. In addition, ME activity was significantly increased in obese agouti-L mouse islets and the mouse MIN-6 cell line. Me siRNA inhibited ME activity and reduced glucose-stimulated insulin secretion and also inhibited NADPH products. Conclusions/interpretation Mouse islets contain ME, which plays a significant role in regulating insulin secretion.

. Enhanced rat ␤-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway.

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