Nicotinamide attenuates the injury-induced decrease of hippocalcin in ischemic brain injury

Investigation of preconditioning and the protective effects of nicotinamide against cerebral ischemia-reperfusion injury in rats

This study investigated the antioxidant and neuroprotective effects of nicotinamide combined with ischemic preconditioning against cerebral ischemia reperfusion (CIR) injury. Thirty-five Wistar albino male rats were randomly divided into five groups: sham, preconditioned ischemia/reperfusion (IP+IR), ischemia/reperfusion (IR), preconditioned ischemia/reperfusion + nicotinamide (IP+IR+N), and ischemia/reperfusion + nicotinamide (IR+N). CIR was achieved with bilateral common carotid artery occlusion. IP+IR and IP+IR+N groups 30 min before ischemia; Three cycles of 10 sec ischemia/30 sec reperfusion followed by 20 min IR were applied. The IP+IR+N and IR+N groups received 500 mg/kg nicotinamide intraperitoneally. After 24 h of reperfusion, a neurological evaluation was performed and vertıcal pole test. Biochemically, malondialdehyde (MDA), glutathione (GSH) levels and catalase (CAT) activity were measured in blood and brain tissue samples. Rates of red neurons, sateliosis and spongiosis were determined histopathologically in the prefrontal cortex areas. After CIR, MDA levels increased significantly in serum and brain tissue in the IR group compared to the sham group, while GSH and CAT activity decreased in the brain tissue (p < 0.05). MDA levels in the tissues were found significantly decreased in the IR+N group compared to the IR group (p < 0.05). Administration of nicotinamide together with IP significantly decreased MDA levels in brain tissue and increased GSH and CAT activity (p < 0.05). Compared to the IR group, the morphological and neurological damage in the prefrontal cortex areas decreased in the IP+IR, IP+IR+N, and IR+N groups (p < 0.05). In addition, red neuron, sateliosis and spongiosis rates increased significantly in the IR group compared to the Sham, IP+IR+N, IR+N groups (p < 0.001 for all). In neurological evaluation, while the neurological score increased and the time on the vertical pole decreased significantly in the IR group, preconditioning, and nicotinamide groups reversed (p < 0.05). The study's results show that nicotinamide administration with ischemic preconditioning alleviates cerebral ischemia/reperfusion injury.

Nicotinamide Phosphoribosyltransferase Positive Allosteric Modulators Attenuate Neuronal Oxidative Stress

Evidence supports boosting nicotinamide adenine dinucleotide (NAD+) to counteract oxidative stress in aging and neurodegenerative disease. One approach is to enhance the activity of nicotinamide phosphoribosyltransferase (NAMPT). Novel NAMPT positive allosteric modulators (N-PAMs) were identified. A cocrystal structure confirmed N-PAM binding to the NAMPT rear channel. Early hit-to-lead efforts led to a 1.88-fold maximum increase in the level of NAD+ in human THP-1 cells. Select N-PAMs were assessed for mitigation of reactive oxygen species (ROS) in HT-22 neuronal cells subject to inflammatory stress using tumor necrosis factor alpha (TNFα). N-PAMs that increased NAD+ more effectively in THP-1 cells attenuated TNFα-induced ROS more effectively in HT-22 cells. The most efficacious N-PAM completely attenuated ROS elevation in glutamate-stressed HT-22 cells, a model of neuronal excitotoxicity. This work demonstrates for the first time that N-PAMs are capable of mitigating elevated ROS in neurons stressed with TNFα and glutamate and provides support for further N-PAM optimization for treatment of neurodegenerative diseases.

New Insights for nicotinamide: Metabolic disease, autophagy, and mTOR

Metabolic disorders, such as diabetes mellitus (DM), are increasingly becoming significant risk factors for the health of the global population and consume substantial portions of the gross domestic product of all nations. Although conventional therapies that include early diagnosis, nutritional modification of diet, and pharmacological treatments may limit disease progression, tight serum glucose control cannot prevent the onset of future disease complications. With these concerns, novel strategies for the treatment of metabolic disorders that involve the vitamin nicotinamide, the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and the cellular pathways of autophagy and apoptosis offer exceptional promise to provide new avenues of treatment. Oversight of these pathways can promote cellular energy homeostasis, maintain mitochondrial function, improve glucose utilization, and preserve pancreatic beta-cell function. Yet, the interplay among mTOR, AMPK, and autophagy pathways can be complex and affect desired clinical outcomes, necessitating further investigations to provide efficacious treatment strategies for metabolic dysfunction and DM.

Proteomic identification of hippocalcin and its protective role in heatstroke-induced hypothalamic injury in mice

Heatstroke is a devastating condition that is characterized by severe hyperthermia and central nervous system dysfunction. However, the mechanism of thermoregulatory center dysfunction of the hypothalamus in heatstroke is unclear. In this study, we established a heatstroke mouse model and a heat-stressed neuronal cellular model on the pheochromocytoma-12 (PC12) cell line. These models revealed that HS promoted obvious neuronal injury in the hypothalamus, with high pathological scores. In addition, PC12 cell apoptosis was evident by decreased cell viability, increased caspase-3 activity, and high apoptosis rates. Furthermore, 14 differentially expressed proteins in the hypothalamus were analyzed by fluorescence two-dimensional difference gel electrophoresis and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Expression changes in hippocalcin (HPAC), a downregulated neuron-specific calcium-binding protein, were confirmed in the hypothalamus of the heatstroke mice and heat-stressed PC12 cells by immunochemistry and western blot. Moreover, HPAC overexpression and HPAC-targeted small interfering RNA experiments revealed that HPAC functioned as an antiapoptotic protein in heat-stressed PC12 cells and hypothalamic injury. Lastly, ulinastatin (UTI), a cell-protective drug that is clinically used to treat patients with heatstroke, was used in vitro and in vivo to confirm the role of HPAC; UTI inhibited heat stress (HS)-induced downregulation of HPAC expression, protected hypothalamic neurons and PC12 cells from HS-induced apoptosis and increased heat tolerance in the heatstroke animals. In summary, our study has uncovered and demonstrated the protective role of HPAC in heatstroke-induced hypothalamic injury in mice.

Nicotinamide prevents sweet beverage-induced hepatic steatosis in rats by regulating the G6PD, NADPH/NADP+ and GSH/GSSG ratios and reducing oxidative and inflammatory stress

The disruption of redox state homeostasis, the overexpression of lipogenic transcription factors and enzymes, and the increase in lipogenic precursors induced by sweetened beverages are determinants of the development of nonalcoholic fatty liver disease. This study evaluated the action of nicotinamide (NAM) on the expression of glucose-6-phosphate dehydrogenase (G6PD) and redox, oxidative, and inflammatory states in a model of nonalcoholic hepatic steatosis induced by high and chronic consumption of carbohydrates. Male rats were provided drinking water with 30% glucose or fructose ad libitum for 12 weeks. Additionally, 30 days after the beginning of carbohydrate administration, some rats were simultaneously provided water with 0.06% or 0.12% NAM for 5h daily over the next 8 weeks. Biochemical profiles and expression levels of G6PD, tumor necrosis factor α (TNFα), and NADPH oxidase 4 (NOX4) were evaluated together with glutathione/glutathione disulfide (GSH/GSSG) and reduced nicotinamide adenine dinucleotide (phosphate)/nicotinamide adenine dinucleotide (phosphate) [NAD(P)H/NAD(P)] ratios and thiobarbituric acid reactive substances (TBARS). The results showed that hepatic steatosis induced by the chronic consumption of glucose or fructose was associated with body weight gain and increased levels of serum glucose, insulin, triacylglycerols, free fatty acids, transaminases, and TBARS. In the liver, the expression and activity of G6PD increased along with the GSSG, TBARS, and TG concentrations. These alterations were reduced by NAM treatment through the attenuation of increases in G6PD expression and activity and in the NADPH/NADP⁺ ratio, thereby slowing liver steatosis. NAM prevents redox, oxidative, and inflammatory alterations induced by high carbohydrate consumption.

Role of nicotinamide (vitamin B3) in acetaminophen-induced changes in rat liver: Nicotinamide effect in acetaminophen-damged liver

Acetaminophen is a widely used analgesic and antipyretic agent, which is safe at therapeutic doses. However, overdoses of acetaminophen induce severe oxidative stress, which leads to acute liver failure. Nicotinamide has proven effective in ameliorating many pathological conditions that occur due to oxidative stress. This study verifies the prophylactic and therapeutic effects of nicotinamide against the hepatic pathophysiological and ultrastructural alterations induced by acetaminophen. Wistar rats intoxicated with an acute overdose of acetaminophen (5g/kg b.wt) were given a single dose of nicotinamide (500mg/kg b.wt) either before or after intoxication. Acetaminophen caused significant elevation in the liver functions and lipid peroxidation marker, and decline in the activities of the hepatic antioxidant enzymes. This oxidative injury was associated with hepatic centrilobular necrosis, hemorrage, vacuolar degeneration, lipid accumulation and mitochondrial alterations. Treating intoxicated rats with nicotinamide (500mg/kg) significantly ameliorated acetaminophen-induced biochemical changes and pathological injuries. However, administering the same dose of nicotinamide to healthy animals or prior to acetaminophen-intoxication induced hepatotoxicity. Caution should be taken when administering high doses of NAM because of its possible hepatotoxicity. Considering the wide use of nicotinamide, there is an important need for monitoring nicotinamide tolerance, safety and efficacy in healthy and diseased subjects.