Depressive-like behavior in mice recently recovered from motor disorders after 3-nitropropionic acid intoxication

Objective Striatum may be involved in depressive disorders according to the neuroimaging analysis and clinical data. However, no animal model at present supported the possible role of striatum in the pathogenesis of depression. In the present study, we have investigated the depressive-like behavior in mice recently intoxicated with 3-nitropropionic acid （3- NP）, a widely known toxin that selectively damages the striatum in the brain. Methods Mouse model was made with subacute systemic 3-NP treatment, and the depressive-like behavior was measured using the duration of immobility during forced swimming test （FST）. Results When the mice at day 15 post-intoxication just totally recovered from motor deficits, the duration of immobility in FST was significantly longer than that in controls. The depressive-like behavior was not due to the fatigue or general sickness following 3-NP intoxication and could be reversed by the antidepressant, desipramine hydrochloride. In two successive FST in 24 h interval, the depressive-like behavior could be observed again in subsequent FST （at day 16 post-intoxication）, and the mice presented a normal ＂learned helplessness＂. Conclusion A novel depression animal model could be established in mice during the initial period of recovery from 3-NP intoxication. The depression-like behavior might occur independently without involvement of cognitive defects, and the striatal lesions may underlie the depression-like behavior attributable to 3-NP intoxication.

Cerebral Ischemic Tolerance Induced by 3-nitropropionic Acid Is Associated with Increased Expression of Erythropoietin in Rats

Summary： To examine the changes in erythropoietin （Epo） protein and its mRNA expression in rat brain subjected to focal ischemia and possible mechanism of the preconditioning of mitochondrial toxin 3-nitropropionic acid （3-NPA）, rats were administrated either vehicle or 3-NPA at a dose of 20 mg/kg, intraperitoneally （ip）, 3 days prior to a 2-h middle cerebral artery occlusion followed by 24- h reperfusion. Infarct volumes were measured by using 2, 3, 5 triphenylte trazolinm chloride （TTC） staining, and Epo protein and its mRNA levels were assessed by immunohistochemistry and reverse transcriptase polymerase chain reaction （RT-PCR）, respectively. Our results showed that after reperfusion, Epo was found to be expressed extensively in the rat brain. It was most apparent in the basal nuclei and hippocampus, and was, to some extent, present in cortex. Preconditioning with 3-NPA caused a reduction in infarct volume. The expression of both Epo protein and mRNA increased significantly in the different brain areas in the 3-NPA pretreated group as compared with the non-pretreated ischemia model group. These results suggested that preconditioning with low dose 3-NPA could induce ischemic tolerance and neuro-protective effects by increasing the Epo expression in the ischemic and ischemia-related areas.

Chemical Preconditioning by 3-nitropropionic Acid Reduces Ischemia-reperfusion Injury in Rat Heart

Summary： This study was designed to investigate the cardioprotective effects of preconditioning with 3-nitropropionic acid, an inhibitor of mitochondrial succinate dehydrogenase. 16 isolated rat hearts were randomly divided into two groups, a treatment group and a control group. The rats of the treatment group were treated intraperitoneally with 3-nitropropionic ac;.d （3-NPA, 4 mg/kg） and the rats of the control group were treated with saline. 24 h after the treatment, the isolated hearts were mounted on a Langendorff apparatus. After 30 min, the hearts were subjected to 30min ischemia and 60-min reperfusion. The HR, LVDP and ±dp/dtmax were measured at preischemia and 30 min, 60 min after the reperfusion. Coronary effluent was collected 15 min after the reperfusion for the determination of CK and LDH. At the end of the 60-min reperfusion the heart was removed for the determination of myocardial SOD and MDA. Our results showed that in the 3-NPA group LVDP and ±dp/dt recovered significantly better, myocardial MDA, CK and LDH were significantly lower and the myocardial SOD was significantly higher than in the control group. It is concluded that chemical preconditioning by 3-nitropropionate has cardioprotective effects against ischemia-reperfusion injury.

Involvement of Apoptosis in 3-nitropropionic Acid-induced Ischemic Tolerance to Transient Focal Cerebral Ischemia in Rats

The involvement of apoptosis in mitochondrial toxin 3 nitropropionic acid (3 NPA) induced ischemic tolerance to transient focal cerebral ischemia in rats and the mechanism was investigated. 3 NPA at a dose of 20 mg/kg or vehicle control was intraperitoneally into the rats. Three days later, rats were exposed to 2 h of middle cerebral artery occlusion followed by 24 h of reperfusion. Infarct volumes were assessed by 2,3,5 triphenyltetrazolinm chloride (TTC) staining 24 h after reperfusion. Neural cell apoptosis in cerebral ischemic penumbra was detected by terminal deoxynucleotidyl transferase mediated dUTP biotin in situ nick end labeling (TUNEL) and flow cytometry methods (FCM). The results showed that as compared to the vehicle treated group, pretreatment with 3 NPA could reduce the infarct volume by 23.3 % and decrease the number of TUNEL positive neural cells and apoptotic percentage by 47 % ( P< 0.05) and 44.9 % ( P< 0 01), respectively. It was concluded that the development of 3 NPA induced ischemic tolerance in brain might be related to the decreases in neural cell apoptosis.

The spatial and temporal relationship between oxidative stress and neuronal degeneration in 3-nitropropionic acid model

The current study investigates the role of oxidative stress and calcium homeostasis in the development of selective striatal lesions in metabolic impairment model caused by 3-nitropropionic acid (3NP). In this report, we examined the distribution of oxidative stress markers and the production of mitochondrial reactive oxygen species in the presence of 3NP in male Sprague-Dawley rats. Protein oxidation was assessed using 3-nitrotyrosine immunoreactivity, while DNA oxidative damage was evaluated by poly (ADP-ribose) polymerase-1 activity. The Reactive Oxygen Species (ROS) production was determined in isolated mitochondrial from striatum and cerebellum of two age groups following 3NP and variable calcium concentration. The results demonstrate that increased 3-nitro-tyrosine level is the most robust in the striatum and the least evident in the cerebellum following 4 days of 3NP treatment. No significant change in the levels of poly ADP-ribosylated proteins was observed, likely due to a rapid PARP-1 cleavage as detected by the appearance of 50 kDa necrotic fragment. In mitochondrial isolates, there was no immediate increase in mitochondrial ROS following 3NP in either striatum or cerebellum;however, calcium addition resulted in a concentration dependent increase in reactive oxygen species in striatal mitochondria of the older animals. These results suggest that in aging, mitochondria become more susceptible to the generation of ROS in conditions that cause a concurrent compromised in mitochondrial calcium concentration. This finding implicates mitochondria dysfunction as a key cellular target in pathological states that are associated with metabolic impairment. The results also reinforce the notion that mitochondrial function in the striatum and cerebellum respond differently to the aging process, which may explain the variable regional vulnerability in 3NP model.

No spatial memory deficit exists in Kunming mice that recently recovered from motor defects following 3-nitropropionic acid intoxication

Objective Numerous studies have described both motor defects and cognitive impairments in several strains of rodents following 3-nitropropionic acid （3-NP） intoxication. In the present study, we investigated spatial recognition memory in Kunming mice that just recovered from motor defects induced by 3-NP. Methods Mouse model was made by systemic subacute 3-NP treatment, and spatial recognition memory was measured through the Y-maze Test, a simple two-trial recognition test. Results （1） On day 15 following 3-NP treatment, affected Kunming mice did not show motor defects in the Rotarod test and presented normal gait again. （2） In the following Y-maze test after lh interval, the percentage （90.0%） of mice showing novel ann preference in 3-NP treatment group was significantly higher than the random chance level （50%）, although it was only slightly higher than that （83.3%） in control group. On day 45 after 3-NP treatment, mice failed to choose unfamiliar novel arm as first choice, and the same occured in the control group. （3） For both post-intoxicated （on day 15 and day 45 following 3-NP treatment） and control groups, the duration in the novel ann and the frequency of entering it, were longer and higher compared with familiar start and other arms. For these mice that recently recovered from motor defects following 3-NP intoxication, no spatial memory deficits were observed through Y-maze Test. Conclusion Kunming mice used in our assays might possess resistance to cognitive impairment induced by 3-NP, which is consistent with previous findings in Swiss EPM-M1 mice.

3-Nitropropionic acid modifies neurotrophin mRNA expression in the mouse striatum: 18S-rRNA is a reliable control gene for studies of the striatum

Objective The aim of the present study was to determine the changes in the mRNA levels of neurotrophins and their receptors in the striatal tissue of mice treated with 3-nitropropionic acid （3-NP）. Methods At 1 and 48 h after the last drug administration, the mRNA expression of nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4/5 as well as their receptors p75, TrkA, TrkB and TrkC, was evaluated using semi-quantitative （semi- Q） and real-time RT-PCR. β-actin mRNA and ribosomal 18S （18S rRNA） were tested as internal controls. Results 3-NP treatment did not affect mRNA expression of all neurotrophins and their respective receptors equally. Also, differences in neurotrophin and receptor mRNA expression were observed between semi-Q and real-time RT-PCR. Real-time RT-PCR was more accurate in evaluating the mRNA expression of the neurotrophins than semi-Q, and 18S rRNA was more reliable than β-actin as an internal control. Conclusion Neurotrophins and their receptors expression is differentially affected by neuronal damage produced by inhibition of mitochondrial respiration with 3-NP treatment in low, sub-chronic doses in vivo.

Involvement of CYP347W1 in neurotoxin 3-nitropropionic acid-based chemical defense in mustard leaf beetle Phaedon cochleariae

Chrysomelina beetlesstore 3-nitropropionic acid in form of a pretoxin,isoxazolin-5-one glucoside-conjugated ester,to protect themselves against predators.Here we identified a cytochrome P450 monooxygenase,CYP347W1,to be involved in the production of the 3-nitropropionic acid moiety of the isoxazolin-5-one glucoside ester.Knocking down CYP347W1 led to a significant depletion in the concentration of the isoxazolin-5-one glucoside ester and an increase in the concentration of the isoxazolin-5-one glucoside in the larval hemolymph.Enzyme assays with the heterologously expressed CYP347W1 showed freeβ-alanine was not the direct substrate.Homology modeling indicated thatβ-alanine-CoA ester can fit into CYP347W1’s active site.Furthermore,we proved that Phaedon cochleariae eggs are not able to de novo synthesize 3-NPA,although both isoxazolin-5-one glucoside and its 3-NPA-conjugated ester are present in the eggs.These results provide direct evidence for the involvement of CYP347W1 in the biosynthesis of a P.cochleariae chemical defense compound.

The microstructural effects of aqueous extract of Garcinia kola(Linn) on the hippocampus and cerebellum of malnourished mice

Objective:To assess the neuroprotective effects of aqueous extract of Garcinia kola on neurotoxin administered malnourished mice adopting histological procedure.Methods:The study was carried out using thirty-two adult malnourished mice which were randomly assigned into four groups(n=8):A,B,C and D.Group A served as control,while the other groups served as the experimental groups.Animals in group A were fed malnourished diet ad libitum and given water liberally.Animals in group B were administered with 3-Nitropropionic acid(3-NP)(neurotoxin)only at 20 rag/kg body weight,group C were given only Garcinia kola extracts,and group D were pre-treated with Garcinia kola extracts at 200 mg/kg for seven days prior to administration of neurotoxin at 20 mg/kg body weight.After three days of neurotoxins administration in the relevant groups,the brains were excised and fixed in formal calcium for histological processing.Results:The study showed that hippocampal and cerebellar neurons of animals in group B exhibited some cellular degeneration and blood vessel blockage,which were not seen in groups A,C and D.Cresyl violet staining was least intense in group B than in groups A,C and D.Despite the fact that animals in group D has equal administration of 3-Nitropropionic acid concentration,there were no traces of neural degeneration as it was evidenced in group B.Conclusions:It is concluded that Garcinia kola has protective effects on the neurons of the hippocampus and cerebellum of malnourished mice.

Effect of Cardioxane and Selenium on Lipoperoxidation and Levels of Dopamine in Rat Brain and Heart

Background: Cardioxane has been probed in patients with advanced malignancies to protect the heart. Selenium, an essential micronutrient exerts varieties of functions such as antioxidant. The aim of this study was to test if cardioxane (CDX) and selenium (Se) have additive antioxidant protective effect on brain and heart, and their relation with dopamine levels. Methods: Thirty-six male Wistar rats divided in groups of 6 animals each, were treated as follows: G1, saline solution 0.9% (control);G2, 100 mg/kg of CDX;G3, 60 μg/kg of Se;G4, 20 mg/kg of 3-nitropropionic acid (3NP);G5, 3NP + CDX and G6, 3NP + Se. 3NP was used as an oxidative stress inducer. Drugs were administered intraperitoneally for 5 days. The animals were sacrificed on the last day of treatment and the brain and heart were extracted and used to measure lipid peroxidation, dopamine, glutathione (GSH), ATPase, calcium, and H2O2. Results: In G2 and G5, dopamine decreased in cortex and striatum while GSH increased in heart, cortex and cerebellum/medulla oblongata. ATPase activity increased in heart and cortex of groups 2, 3, 5 and 6. Lipoperoxidation and H2O2 increased in cortex of animals treated with 3NP. Conclusion: These results suggest that CDX increases antioxidant capacity in the brain and heart while selenium promotes alteration in dopamine metabolism in view of the capacity of 3NP to generate free radicals.