Histochemical Observation of Nitric Oxide Synthase in Trigeminal Ganglion of Rats with Experimental Pulpitis

Summary: In order to understand the roles of nitric oxide (NO) in pulpalgia and pulpitis, the histochemistry of nitric oxide synthase (NOS) in the neurons of trigeminal ganglion in experimental pulpitis rat and human inflammatory dental pulp tissues were histochemically studied by NADPH diaphorase (NADPH D) techniques. Results showed that NADPH D positive neurons were scattered in rat trigeminal ganglions, but the sizes of positive neurons were not changed. None of NOS positive fibers was found in human normal and inflammatory dental pulp tissues. The results suggested that NOS in trigeminal ganglion might play an important role in sensory transmission and regulation of pulpalgia. The absence of NOS positive nerves in human pulp suggested that NO may not be related to inflammatory stimulation and transmission in dental pulp tissues.

The emerging role of nitric oxide in the synaptic dysfunction of vascular dementia

With an increase in global aging,the number of people affected by cerebrovascular diseases is also increasing,and the incidence of vascular dementia-closely related to cerebrovascular risk-is increasing at an epidemic rate.However,few therapeutic options exist that can markedly improve the cognitive impairment and prognosis of vascular dementia patients.Similarly in Alzheimer’s disease and other neurological disorders,synaptic dysfunction is recognized as the main reason for cognitive decline.Nitric oxide is one of the ubiquitous gaseous cellular messengers involved in multiple physiological and pathological processes of the central nervous system.Recently,nitric oxide has been implicated in regulating synaptic plasticity and plays an important role in the pathogenesis of vascular dementia.This review introduces in detail the emerging role of nitric oxide in physiological and pathological states of vascular dementia and summarizes the diverse effects of nitric oxide on different aspects of synaptic dysfunction,neuroinflammation,oxidative stress,and blood-brain barrier dysfunction that underlie the progress of vascular dementia.Additionally,we propose that targeting the nitric oxide-sGC-cGMP pathway using certain specific approaches may provide a novel therapeutic strategy for vascular dementia.

Neuronal nitric oxide synthase/reactive oxygen species pathway is involved in apoptosis and pyroptosis in epilepsy

Dysfunction of neuronal nitric oxide synthase contributes to neurotoxicity,which triggers cell death in various neuropathological diseases,including epilepsy.Studies have shown that inhibition of neuronal nitric oxide synthase activity increases the epilepsy threshold,that is,has an anticonvulsant effect.However,the exact role and potential mechanism of neuronal nitric oxide synthase in seizures are still unclear.In this study,we performed RNA sequencing,functional enrichment analysis,and weighted gene coexpression network analysis of the hippocampus of tremor rats,a rat model of genetic epilepsy.We found damaged hippocampal mitochondria and abnormal succinate dehydrogenase level and Na+-K+-ATPase activity.In addition,we used a pilocarpine-induced N2a cell model to mimic epileptic injury.After application of neuronal nitric oxide synthase inhibitor 7-nitroindazole,changes in malondialdehyde,lactate dehydrogenase and superoxide dismutase,which are associated with oxidative stress,were reversed,and the increase in reactive oxygen species level was reversed by 7-nitroindazole or reactive oxygen species inhibitor N-acetylcysteine.Application of 7-nitroindazole or N-acetylcysteine downregulated the expression of caspase-3 and cytochrome c and reversed the apoptosis of epileptic cells.Furthermore,7-nitroindazole or N-acetylcysteine downregulated the abnormally high expression of NLRP3,gasdermin-D,interleukin-1βand interleukin-18.This indicated that 7-nitroindazole and N-acetylcysteine each reversed epileptic cell death.Taken together,our findings suggest that the neuronal nitric oxide synthase/reactive oxygen species pathway is involved in pyroptosis of epileptic cells,and inhibiting neuronal nitric oxide synthase activity or its induced oxidative stress may play a neuroprotective role in epilepsy.

Metformin promotes angiogenesis and functional recovery in aged mice after spinal cord injury by adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway

Treatment with metformin can lead to the recovery of pleiotropic biological activities after spinal cord injury.However,its effect on spinal cord injury in aged mice remains unclear.Considering the essential role of angiogenesis during the regeneration process,we hypothesized that metformin activates the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway in endothelial cells,thereby promoting microvascular regeneration in aged mice after spinal cord injury.In this study,we established young and aged mouse models of contusive spinal cord injury using a modified Allen method.We found that aging hindered the recovery of neurological function and the formation of blood vessels in the spinal cord.Treatment with metformin promoted spinal cord microvascular endothelial cell migration and blood vessel formation in vitro.Furthermore,intraperitoneal injection of metformin in an in vivo model promoted endothelial cell proliferation and increased the density of new blood vessels in the spinal cord,thereby improving neurological function.The role of metformin was reversed by compound C,an adenosine monophosphate-activated protein kinase inhibitor,both in vivo and in vitro,suggesting that the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway likely regulates metformin-mediated angiogenesis after spinal cord injury.These findings suggest that metformin promotes vascular regeneration in the injured spinal cord by activating the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway,thereby improving the neurological function of aged mice after spinal cord injury.

Identification and Pathogen Stimulation Patterns of Neuronal Nitric Oxide Synthase(nNOS)in Black Rockfish(Sebastes schlegelii)

Neuronal nitric oxide synthase(nNOS)was the producer of nitric oxide(NO)which played important gas messenger molecules in biological process.It also can take effect as immune regulation molecule in organism.Black rockfish(Sebastes schlegelii)is an important economic fish which were widely farmed in East Asia countries.Meanwhile,the pathogenic bacteria such as the Edwardsiella tarda and Vibrio anguillarum in seawater always brought serious obstacles to their healthy growth.In order to explore the expression pattern of n NOS gene under the pathogen stimulation and predict its immune function,the n NOS gene in black rockfish named Ssn NOS was identified.It was 3780 bp in length,located on chromosome 6,and contained 27 coding domain sequence(CDs).According to the phylogenetic analysis,the Ssn NOS showed closest relative to the counterpart gene of swamp eel(Monopterus albus).Meanwhile,analysis of Ssn NOS expression in various healthy tissues showed that Ssn NOS expression level was highest in healthy brain tissues,followed by intestinal tissues.In addition,Ssn NOS showed significant expression changes in response to stimulation by two pathogens.Particular in gill,the expression of Ssn NOS after pathogenic stimulation increased significantly.The Elisa analysis showed the Ssn NOS content in gills was much higher than that in other tissues at all time points.Moreover,the expression patterns of Ssn NOS in brain,intestine and kidney after stimulation by pathogens showed a distinct expression pattern which first down-regulated and then up-regulated.Therefore,the Ssn NOS may be an important signaling molecule for fish to respond rapidly in immune stimulation.

Effects of icariin on erectile function and expression of nitric oxide synthase isoforms in castrated rats

Aim： To investigate the effect of icariin on erectile function and the expression of nitric oxide synthase （NOS） isoforms in castrated rats. Methods： Thirty-two adult male Wistar rats were randomly divided into one shamoperated group （A） and three castrated groups （B, C and D）. One week after surgery, rats were treated with normal saline （groups A and B） or oral icariin （1 mg/[kg·day] for group C and 5 mg/[kg·day] for group D） for 4 weeks. One week after treatment, the erectile function of the rats was assessed by measuring intracavernosal pressure （ICP） during electrostimulation of the cavernosal nerve. The serum testosterone （ST） levels, the percent of smooth muscle （PSM） in trabecular tissue, and the expression of mRNA and proteins of neuronal nitric oxide synthase （nNOS）, inducible nitric oxide synthase （iNOS）, endothelial nitric oxide synthase （eNOS） and phosphodiesterase V （PDES） in corpus cavernosum （CC） were also evaluated. Results： ICP, PSM, ST and the expression of nNOS, iNOS, eNOS and PDE5 were significantly decreased in group B compared with those in group A （P 〈 0.01）. However, ICE PSM and the expression of nNOS and iNOS were increased in groups C and D compared with those in group B （P 〈 0.05）. Changes in ST and the expression of eNOS and PDE5 were not significant （P 〉 0.05） in groups C and D compared with those in group B. Conclusion： Oral treatment with icariin （〉 98.6 % purity） for 4 weeks potentially improves erectile function. This effect is correlated with an increase in PSM and the expression of certain NOS in the CC of castrated rats. These results suggest that icariin may have a therapeutic effect on erectile dysfunction.

Role of brain-derived neurotrophic factor and neuronal nitric oxide synthase in stress-induced depression

BACKGROUND： Accumulated evidence indicates an important role for hippocampal dendrite atrophy in development of depression, while brain-derived neurotrophic factor （BDNF） participates in hippocampal dendrite growth. OBJECTIVE： To discuss the role of BDNF and neuronal nitric oxide synthase （nNOS） in chronic and unpredictable stress-induced depression and the pathogenesis of depression. DESIGN, TIME AND SETTING： Randomized, controlled animal experiment. The experiment was carded out from October 2006 to May 2007 at the Department of Animal Physiology, College of Life Science, Shaanxi Normal University. MATERIALS： Thirty-seven male Sprague-Dawley rats weighing 250-300 g at the beginning of the experiment were obtained from Shaanxi Provincial Institute of Traditional Chinese Medicine （Xi＇an, China）. BDNF antibody and nNOS antibody were provided by Santa Cruz （USA）. K252a （BDNF inhibitor） and 7-NI （nNOS inhibitor） were provided by Sigma （USA）. METHODS： Animals were randomly divided into five groups： Control group, chronic unpredicted mild stress （CUMS） group, K252a group, K252a＋7-NI group and 7-NI＋CUMS group. While the Control, K252a and K252a＋7-NI groups of rats not subjected to stress had free access to food and water, other groups of rats were subjected to nine stressors randomly applied for 21 days, with each stressor applied 2-3 times. On days 1, 7, 14 and 21 during CUMS, rats received microinjection of 1 μL of physiological saline in the Control and CUMS groups, 1 ~ L of K252a in the K252a group, 1 μL of K252a and 7-NI in the K252a＋7-NI group, and 1 μL of 7-NI in the 7-NI＋CUMS group. We observed a variety of alterations in sucrose preference, body weight change, open field test and forced swimming test, and observed the expression of BDNF and nNOS in rat hippocampus by immunohistochemistry; MAIN OUTCOME MEASURES： ① A variety.of behavioral alterations of rats; ② The expression of BDNF and nNOS in rat hippocampus. RESULTS： Compared with the Control group, the behavior of the CUMS rats was significantly depressed, the expression of BDNF decreased （P 〈 0.01） but the expression of nNOS increased （P 〈 0.01）. The behavior of rats given intra-hippocampal injection of BDNF inhibitor was significantly depressed and the expression of nNOS was significantly increased （P 〈 0.01）. Intra-hippocampal injections of an nNOS inhibitor reversed the depression-like behavioral changes induced by CUMS or intra-hippocampal injection of BDNF inhibitor. CONCLUSION： CUMS induced a decrease in expression of BDNF and an increase in expression of NO in the hippocampus, which may lead to depression.

Nitric oxide synthase distribution in esophageal mucosa and hemodynamic changes in rats with cirrhosis

AIM To observe the nitric oxide synthase (NOS) distribution in the esophageal mucosa andhemodynamic changes in cirrhotic rats.METHODS NOS distribution in the loweresophagus of rats with carbon tetrachlorideinduced cirrhosis was assessed by using NADPHdiaphorase (NADPH-d ) histochemical method.Concentration of NO in serum were measured byfluorometric assay. Mean arterial pressure(MAP), cardiac output (CO), cardiac index (CI),splanchnic vascular resistance (SVR ), andsplanchnic blood flow (SBF ) were alsodetermined using 5’CO-labeled microspheretechnique.RESULTS Intensity of NOS staining in theesophageal epithelium of cirrhotic rats wassignificantly stronger than that in controls.There was a NOS--positive staining area in theendothelia of esophageal submucosal vessels ofcirrhotic rats, but the NOS staining was negativein normal rats. NO concentration of serum incirrhotic rats were significantly higher incomparison with that of controls. Cirrhotic ratshad significantly lower MAP, SVR and higherSBF than those of the controls.CONCLUSION SPlanchnic hyperdynamiccirculatory state was observed in rats withcirrhosis. The endogenous NO may play animportant role in development of esophagealvarices and in changes of hemodynamics incirrhosis.

Effect of warm acupuncture on nitric oxide synthase and calcitonin gene-related peptide in a rat model of lumbar nerve root compression

BACKGROUND： Varying degrees of inflammatory responses occur during lumbar nerve root compression. Studies have shown that nitric oxide synthase （NOS） and calcitonin gene-related peptide （CGRP） are involved in secondary disc inflammation. OBJECTIVE： To observe the effects of warm acupuncture on the ultrastructure of inflammatory mediators in a rat model of lumbar nerve root compression, including NOS and CGRP contents. DESIGN, TIME AND SETTING： Randomized, controlled study, with molecular biological analysis, was performed at the Experimental Center, Sixth People＇s Hospital Affiliated to Shanghai Jiao Tong University, between September 2006 and April 2007. MATERIALS： Acupuncture needles and refined Moxa grains were purchased from Shanghai Taicheng Technology Development Co., Ltd., China; Mobic tablets were purchased from Shanghai Boehringer Ingelheim Pharmaceuticals Co., Ltd., China; enzyme linked immunosorbent assay （ELISA） kits for NOS and CGRP were purchased from ADL Biotechnology, Inc., USA. METHODS： A total of 50, healthy, adult Sprague-Dawley rats, were randomly divided into five groups normal, model, warm acupuncture, acupuncture, and drug, with 10 rats in each group. Rats in the four groups, excluding the normal group, were used to establish models of lumbar nerve root compression. After 3 days, Jiaji points were set using reinforcing-reducing manipulation in the warm acupuncture group. Moxa grains were burned on each needle, with 2 grains each daily. The acupuncture group was the same as the warm acupuncture group, with the exception of non-moxibustion. Mobic suspension （3.75 mg/kg） was used in the oral drug group, once a day. Treatment of each group lasted for 14 consecutive days. Modeling and medication were not performed in the normal group. MAIN OUTCOME MEASURES： The ultrastructure of damaged nerve roots was observed with transmission electron microscopy; NOS and CGRP contents were measured using ELISA. RESULTS： The changes of the radicular ultramicrostructure were characterized by Wallerian degeneration; nerve fibers were clearly demyelinated; axons collapsed or degenerated; outer Schwann cell cytoplasm was swollen and its nucleus was compacted. Compared with the normal group, NOS and CGRP contents in the nerve root compression zone in the model group were significantly increased （P 〈 0.01）. Nerve root edema was improved in the drug, acupuncture and the warm acupuncture groups over the model group. NOS and CGRP expressions were also decreased with the warm acupuncture group having the lowest concentration （P 〈 0.01）. CONCLUSION： In comparison to the known effects of Mobic drug and acupuncture treatments, the warm acupuncture significantly decreased NOS and CGRP expression which helped improve the ultrastructure of the compressed nerve root.

Simvastatin Increases the Activity of Endothelial Nitric Oxide Synthase via Enhancing Phosphorylation

3-hydroxy-3-methylgulutaryl-coenzyme A （HMG-CoA） reductase inhibitors or statins are a kind of lipid-lowering agents and have been used for the prevention and treatment of Cardiovascular diseases. Recent studies suggested that statins, besides lowering cholesterol, may protect vessels by enhancing the activity of endothelial nitric oxide synthase （eNOS）. In the present study, we investigated if simvastatin increases eNOS activity through its phosphorylation in 293 cells （293-eNOS） with stable expression of eNOS. The results showed that incubation of 293-eNOS cells with simvastatin （10 μm/L） for 2 h significantly increased in the activity of eNOS as shown by the conversion of L-arginine to L-citrulline （2889.70±201.51 versus 5630.18＋218.75 pmol/min . mg proteins） （P〈0.01）. Western blotting revealed that simvastatin increased phosphorylation of eNOS at 1177 （ser） and also 495 （thr） but did not affect the overall expression of eNOS or inducible NOS. Further study found that simvastatin raised phosphorylation levels of Akt and AMPK, and such effect could be antagonized by Akt inhibitor or AMPK inhibitor. These results suggest that simvastatin could stimulate,the activity of eNOS via its phosphorylation by Akt and AMPK, which provides a new mechanism, other than lipid-lowering effect, for the cardiovascular protection of statins.

Role of nitric oxide synthase and cyclooxygenase in hyperdynamic splanchnic circulation of portal hypertension

BACKGROUND: Nitric oxide (NO) and prostacyclin (PGI(2)) are both powerful vasoactive substances correlated with the hyperhemodynamics of portal hypertension (PHT), a common syndrome characterized by a pathological increase in portal venous pressure. The purpose of the present study was to evaluate the possible interaction between these two endothelial vasodilators, together with their respective roles in the hyperdynamic splanchnic circulation of PHT. METHODS: Ninety-six male Sprague-Dawley rats were randomly divided into three groups: intrahepatic portal hypertension (IHPH) induced by injection of CCI4 (n=31), prehepatic portal hypertension (PHPH) induced by partial stenosis of the portal vein (n=33), and sham-operated controls (SO) (n=32). Animals of each group received indomethacin (INDO), a cyclooxygenase (COX) inhibitor, either short-term (7 days) or long-term (15 days), with saline as control. Free portal pressure (FPP), together with the concentration of NO and PGI(2) in serum were measured. The activity of constitutive nitric oxide synthase (cNOS) and inducible nitric oxide synthase (iNOS) in the abdominal aorta and small intestine were determined by spectrophotometry. RT-PCR was performed to measure the levels of cNOS and iNOS mRNA in the arteries and small intestines. RESULTS: Compared with SO rats, the concentrations of NO and PGI(2) in PHT rats were elevated, which were consistent with the increased FPP (P<0.05). Although administration of INDO persistently decreased the concentration of PGI(2) in serum (P<0.05), the long-term INDO-treated IHPH and PHPH groups had restored splanchnic hyperdynamic circulation, demonstrated by the enhanced FPP (P<0.05). Furthermore, the changes of dynamic circulatory state in both IHPH and PHPH rats were concomitant with the expression and activity of iNOS and the concentration of NO (P<0.05). Although the expression and activity of cNOS in abdominal aorta of PHT rats were higher than in SO rats (P<0.05), there was no difference in small intestinal tissues between PHT and SO rats (P>0.05). Moreover, the changes of iNOS activity and mRNA expression were more marked than cNOS in PHT rats, and there was no difference in expression and activity of cNOS between PHT rats treated by short- and long-term INDO (P>0.05). CONCLUSIONS: iNOS plays an important role in the hemodynamic abnormalities of PHT induced by overproduction of NO. There is a possible interaction between PGI(2) and NO in hyperbemodynamics of PHT, but PGI(2) may not be a mediator in the formation and development of the hyperdynamic circulatory state in PHT rats.

Targeting neuronal nitric oxide synthase as a valuable strategy for the therapy of neurological disorders

The management of neurological disorders have huge and increasing human and economic costs. Despite this, there is a scarcity of effective therapeutics, and there is an extreme urgency for new and real treatments. In this short review we analyze some promising advancements in the search of new bioactive molecules targeting neuronal nitric oxide synthase （nNOS）, an enzyme deputed to the biosynthesis of nitric oxide （NO）. In different conditions of neuronal damages, this molecule is overproduced, contributing to the pathogenesis and progression of neuronal diseases. Two main approaches to modulate nNOS are discussed： a first one consisting in the direct inhibition of the enzyme by means of small organic molecules, which can be also active against other different targets involved in such diseases. A second section is dedicated to molecules able to prevent the formation of the ternary complex N-methyl-D-aspartate （NMDA）type glutamate receptors, postsynaptic density-95 （PSD95） protein-nNOS, which is necessary to activate the latter for the biosynthesis of NO.

Attenuation of Nitric Oxide Synthase Gene Expression in Rat Lung Induced by Hypoxia

In order to investigate the role of nitric oxide(NO) in pathogenesis of hypoxic pulmonary hypertension(HPH), the mean pulmonary arterial pressure(mPAP), mRNA expression of NO synthase(NOS) in lung tissues, cGMP levels, and their relationships were studied in rats exposed to hypoxia from 8 h to 28days. The results showed that mPAP began to increase in animals exposed to 10 % O2 for 8 h. Moreover, the longer the exposure, the higher the mPAP.Northern blot analysis and dot blot hybridization indicated that mRNA expression of NO in lung tissues of hypoxic rats tended to decrease with exposure days, but that of β-actin which acted as a control did not alter. The cGMP levels of plasma and lung tissues in hypoxic rats also inclined to be lower with exposure days. A marked negative correlations between the changes of cGMP levels and those of mPAP were found. It was suggested that mRNA expression of NOS gene was attenuated in hypoxic lung tissues, which may be one of important pathogenetic mechanisms of HPH.

Nerve growth factor and inducible nitric oxide synthase expression in the mesencephalon and diencephalon, as well as visual-and auditory-related nervous tissues, in a macaque model of type 2 diabetes

The present study detected distribution and expression of nerve growth factor and inducible nitric oxide synthase in the mesencephalon and diencephalon, as well as visual- and auditory-related nervous tissues, in a macaque model of type 2 diabetes using immunohistochemistry. Results showed that nerve growth factor expression decreased, but inducible nitric oxide synthase expression increased, in the mesencephalon and diencephalon, as well as visual- and auditory- related nervous tissues. These results suggested that nerve growth factor and inducible nitric oxide synthase play an important role in regulating the development of diabetic visual- and auditory-related diseases.

Inhibition of nitric oxide synthase aggravates brain injury in diabetic rats with traumatic brain injury

Studies have shown that hyperglycemia aggravates brain damage by affecting vascular endothelial function. However, the precise mechanism remains unclear. Male Sprague-Dawley rat models of diabetes were established by a high-fat diet combined with an intraperitoneal injection of streptozotocin. Rat models of traumatic brain injury were established using the fluid percussion method. Compared with traumatic brain injury rats without diabetic, diabetic rats with traumatic brain injury exhibited more severe brain injury, manifested as increased brain water content and blood-brain barrier permeability, the upregulation of heme oxygenase-1, myeloperoxidase, and Bax, the downregulation of occludin, zona-occludens 1, and Bcl-2 in the penumbra, and reduced modified neurological severity scores. The intraperitoneal injection of a nitric oxide synthase inhibitor N(5)-(1-iminoethyl)-L-ornithine(10 mg/kg) 15 minutes before brain injury aggravated the injury. These findings suggested that nitric oxide synthase plays an important role in the maintenance of cerebral microcirculation, including anti-inflammatory, anti-oxidative stress, and anti-apoptotic activities in diabetic rats with traumatic brain injury. The experimental protocols were approved by the Institutional Animal Care Committee of Harbin Medical University, China(approval No. ky2017-126) on March 6, 2017.

Nitric oxide synthase 2 gene polymorphisms are associated with prostatic volume in Korean men with benign prostatic hyperplasia

The precise aetiology of benign prostatic hyperplasia （BPH） remains unclear; however, it is known that immunological inflammatory processes have a role in the pathogenesis of BPH initiation and progression. Nitric oxide synthase 2 （NOS2） inducible expression is closely correlated with prostatic disease, including prostate cancer and BPH. The aim of this study was to investigate the relationship between NOS2 polymorphisms and BPH. With a cohort of 205 controls and 229 BPH subjects, we genotyped three single nucleotide polymorphisms （SNPs） in the NOS2 gene, including rs2779248 （promoter, -278 T/C）, rs 10459953 （5＇-untranslated region） and rs2297518 （exon 16, missense, Ser608Leu）, using direct sequencing and restriction fragment length polymorphism. The genotypic and allelic frequencies between control and BPH subjects were compared, and the associations among the BPH subjects were analyzed. SNPStats, SNPAnalyzer and HelixTree programmes were used to analyze SNPs. There was no association on SNPs between control and BPH subjects. When BPH subjects were analyzed, there was no association on SNPs between the low and high prostate-specific antigen groups. However, one SNP （rs 10459953, odds ratio [OR] = 0.44, 95% confidence interval [CI] = 0.29-0.65, P 〈 0.0001, in codominant model; OR = 0.23, 95% CI = 0.12-0.46, P 〈 0.0001, in dominant model; and OR = 0.46, 95% CI = 0.24-0.86, P = 0.015, in recessive model） was associated with prostatic volume in BPH. We detected a strong association in genotype frequencies of NOS2 SNP （rs10459953） between subjects with small and large prostatic volume in BPH. The result suggests that NOS2 may be associated with prostatic volume in BPH.

Biliverdin Reductase-A correlates with inducible nitric oxide synthasein in atorvastatin treated aged canine brain

Alzheimer’s disease is a neurodegenerative disorder characterized by progressive cognitive impairment and neuropathology. Recent preclinical and epidemiological studies proposed statins as a possible therapeutic drug for Alzheimer’s disease, but the exact mechanisms of action are still unknown. Biliverdin reductase-A is a pleiotropic enzyme involved in cellular stress responses. It not only transforms biliverdin-IX alpha into the antioxidant bilirubin-IX alpha but its serine/threonine/ tyrosine kinase activity is able to modulate cell signaling networks. We previously reported the beneficial effects of atorvastatin treatment on biliverdin reductase-A and heme oxygenase-1 in the brains of a well characterized pre-clinical model of Alzheimer’s disease, aged beagles, together with observed improvement in cognition. Here we extend our knowledge of the effects of atorvastatin on inducible nitric oxide synthase in parietal cortex, cerebellum and liver of the same animals. We demonstrated that atorvastatin treatment （80 mg/day for 14.5 months） to aged beagles selectively increased inducible nitric oxide synthase in the parietal cortex but not in the cerebellum. In contrast, inducible nitric oxide synthase protein levels were significantly decreased in the liver. Significant positive correlations were found between biliverdin reductase-A and inducible nitric oxide synthase as well as heme oxygenase-1 protein levels in the parietal cortex. The opposite was observed in the liver. Inducible nitric oxide synthase up-regulation in the parietal cortex was positively associated with improved biliverdin reductase-A functions, whereas the oxidative-induced impairment of biliverdin reductase-A in the liver negatively affected inducible nitric oxide synthase expression, thus suggesting a role for biliverdin reductase-A in atorvastatin-dependent inducible nitric oxide synthase changes. Interestingly, increased inducible nitric oxide synthase levels in the parietal cortex were not associated with higher oxidative/nitrosative stress levels. We hypothesize that biliverdin reductase-A-dependent inducible nitric oxide synthase regulation strongly contributes to the cognitive improvement observed following atorvastatin treatment.

Localization of nitric oxide synthase in the developing gonads of amphioxus Branchiostoma belcheri tsingtauense

The localization of nitric oxide synthases （NOS） is dealed with in the developing gonads of amphioxus Branchiostoma belcheri tsingtauense. It was found by NADPH-diaphorase staining that （1） NOS activity was present in the nuclear membranes of germinal vesicles during the entire period ofoocyte development; （2） NOS was localized in both the nuclear membranes and the perinuclear region of cytoplasm in the vitellogenetic oocytes; （3） NOS was relocated in the cortical layer in the mature egg; （4） NOS activity was present in spermatocytes, but not in the spermatogonia in the middle of October; （5） NOS was detected in both spermatozoa and spermatids as well as spermatocytes during the breeding season. This is the first report on the distribution pattern of NOS in the developing gonads in protochordates. These results suggest a role for NOS in the functioning of the nuclear membranes and yolk synthesis during oogenesis and in cell division and differentiation during spermatogenesis.

Effect of Magnesium on Nitric Oxide Synthase of Neurons in Cortex during Early Period of Cerebral Ischemia

Summary: To investigate the effect of magnesium on nitric oxide synthase (NOS) of neurons in cortex during early cerebral ischemic period, a rat model of middle cerebral artery occlusion (MCAO) was established. The results showed that the NOS activity of neurons in cortex was in- creased significantly at 15 min after MCAO, reached its peak at 30 min after MCAO and returned to normal levels at 60 min after MCAO. The NOS activity of neurons in the magnesium-treated group was decreased significantly as compared with that in the ischemic group at 15 min and 30 ruin after MCAO respectively. The results suggested that magnesium could inhibit the elevated NOS activity of neurons in cortex induced by cerebral ischemia.