Cinthia M. Mazzanti

Resveratrol prevents memory deficits and the increase in acetylcholinesterase activity in streptozotocin-induced diabetic rats

The objective of the present study was to investigate the effect of the administration of resveratrol (RV) on memory and on acetylcholinesterase (AChE) activity in the cerebral cortex, hippocampus, striatum, hypothalamus, cerebellum and blood in streptozotocin-induced diabetic rats. The animals were divided into six groups (n=6-13): Control/saline; Control/RV 10 mg/kg; Control/RV 20 mg/kg; Diabetic/saline; Diabetic/RV 10 mg/kg; Diabetic/RV 20 mg/kg. One day after 30 days of treatment with resveratrol the animals were submitted to behavioral tests and then submitted to euthanasia and the brain structures and blood were collected. The results showed a decrease in step-down latency in diabetic/saline group. Resveratrol (10 and 20 mg/kg) prevented the impairment of memory induced by diabetes. In the open field test, no significant differences were observed between the groups. In relation to AChE activity, a significant increase in diabetic/saline group (P<0.05) was observed in all brain structures compared to control/saline group. However, AChE activity decreased significantly in control/RV10 and control/RV20 (P<0.05) groups in cerebral cortex, hippocampus and striatum, while no significant differences were observed in diabetic/RV10 and diabetic/RV20 groups in all brain structures compared to control/saline group. Blood AChE activity increased significantly in diabetic/saline group (P<0.05) decreased in control/RV10, control/RV20 and diabetic/RV20 groups (P<0.05) compared to control/saline group. In conclusion, the present findings showed that treatment with resveratrol prevents the increase in AChE activity and consequently memory impairment in diabetic rats, demonstrating that this compound can modulate cholinergic neurotransmission and consequently improve cognition.

N-acetylcysteine prevents memory deficits, the decrease in acetylcholinesterase activity and oxidative stress in rats exposed to cadmium

The present study investigated the effect of the administration of N-acetylcysteine (NAC), on memory, on acetylcholinesterase (AChE) activity and on lipid peroxidation in different brain structures in cadmium (Cd)-exposed rats. The rats received Cd (2 mg/kg) and NAC (150 mg/kg) by gavage every other day for 30 days. The animals were divided into four groups (n=12-13): control/saline, NAC, Cd, and Cd/NAC. The results showed a decrease in step-down latency in the Cd-group, but NAC reversed the impairment of memory induced by Cd intoxication. Rats exposed to Cd and/or treated with NAC did not demonstrate altered shock sensitivity. Decreased AChE activity was found in hippocampus, cerebellum and hypothalamus in the Cd-group but NAC reversed this effect totally or partially while in cortex synaptosomes and striatum there was no alteration in AChE activity. An increase in TBARS levels was found in hippocampus, cerebellum and hypothalamus in the Cd-group and NAC abolished this effect while in striatum there was no alteration in TBARS levels. Urea and creatinine levels were increased in serum of Cd-intoxicated rats, but NAC was able to abolish these undesirable effects. The present findings show that treatment with NAC prevented the Cd-mediated decrease in AChE activity, as well as oxidative stress and consequent memory impairment in Cd-exposed rats, demonstrating that this compound may modulate cholinergic neurotransmission and consequently improve cognition. However, it is necessary to note that the mild renal failure may be a contributor to the behavioral impairment found in this investigation.

Neuroprotective effect of anthocyanins on acetylcholinesterase activity and attenuation of scopolamine-induced amnesia in rats

Anthocyanins are a group of natural phenolic compounds responsible for the color to plants and fruits. These compounds might have beneficial effects on memory and have antioxidant properties. In the present study we have investigated the therapeutic efficacy of anthocyanins in an animal model of cognitive deficits, associated to Alzheimers disease, induced by scopolamine. We evaluated whether anthocyanins protect the effects caused by SCO on nitrite/nitrate (NOx) levels and Na+,K+‐ATPase and Ca2+‐ATPase and acetylcholinesterase (AChE) activities in the cerebral cortex and hippocampus (of rats. We used 4 different groups of animals: control (CTRL), anthocyanins treated (ANT), scopolamine‐challenged (SCO), and scopolamine + anthocyanins (SCO + ANT). After seven days of treatment with ANT (200 mg kg−1; oral), the animals were SCO injected (1 mg kg−1; IP) and were performed the behavior tests, and submitted to euthanasia. A memory deficit was found in SCO group, but ANT treatment prevented this impairment of memory (P < 0.05). The ANT treatment per se had an anxiolytic effect. AChE activity was increased in both in cortex and hippocampus of SCO group, this effect was significantly attenuated by ANT (P < 0.05). SCO decreased Na+,K+‐ATPase and Ca2+‐ATPase activities in hippocampus, and ANT was able to significantly (P < 0.05) prevent these effects. No significant alteration was found on NOx levels among the groups. In conclusion, the ANT is able to regulate cholinergic neurotransmission and restore the Na+,K+‐ATPase and Ca2+‐ATPase activities, and also prevented memory deficits caused by scopolamine administration.

Quercetin protects the impairment of memory and anxiogenic-like behavior in rats exposed to cadmium: Possible involvement of the acetylcholinesterase and Na+,K+-ATPase activities

The present study investigated the effects of quercetin in the impairment of memory and anxiogenic-like behavior induced by cadmium (Cd) exposure. We also investigated possible alterations in acetylcholinesterase (AChE), Na(+),K(+)-ATPase and δ-aminolevulinate dehydratase (δ-ALA-D) activities as well as in oxidative stress parameters in the CNS. Rats were exposed to Cd (2.5mg/kg) and quercetin (5, 25 or 50mg/kg) by gavage for 45days. Animals were divided into eight groups (n=10-14): saline/control, saline/Querc 5mg/kg, saline/Querc 25mg/kg, saline/Querc 50mg/kg, Cd/ethanol, Cd/Querc 5mg/kg, Cd/Querc 25mg/kg and Cd/Querc 50mg/kg. Results demonstrated that Cd impaired memory has an anxiogenic effect. Quercetin prevented these harmful effects induced by Cd. AChE activity decreased in the cerebral cortex and hippocampus and increased in the hypothalamus of Cd-exposed rats. The Na(+),K(+)-ATPase activity decreased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin prevented these effects in AChE and Na(+),K(+)-ATPase activities. Reactive oxygen species production, thiobarbituric acid reactive substance levels, protein carbonyl content and double-stranded DNA fractions increased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin totally or partially prevents these effects caused by Cd. Total thiols (T-SHs), reduced glutathione (GSH), and reductase glutathione (GR) activities decreased and glutathione S-transferase (GST) activity increased in Cd exposed rats. Co-treatment with quercetin prevented reduction in T-SH, GSH, and GR activities and the rise of GST activity. The present findings show that quercetin prevents alterations in oxidative stress parameters as well as AChE and Na(+),K(+)-ATPase activities, consequently preventing memory impairment and anxiogenic-like behavior displayed by Cd exposure. These results may contribute to a better understanding of the neuroprotective role of quercetin, emphasizing the influence of this flavonoid in the diet for human health, possibly preventing brain injury associated with Cd intoxication.

Anthocyanins restore behavioral and biochemical changes caused by streptozotocin-induced sporadic dementia of Alzheimer's type.

AIMS The aim of this study was to analyze if the pre-administration of anthocyanin on memory and anxiety prevented the effects caused by intracerebroventricular streptozotocin (icv-STZ) administration-induced sporadic dementia of Alzheimers type (SDAT) in rats. Moreover, we evaluated whether the levels of nitrite/nitrate (NOx), Na(+),K(+)-ATPase, Ca(2+)-ATPase and acethylcholinesterase (AChE) activities in the cerebral cortex (CC) and hippocampus (HC) are altered in this experimental SDAT. MAIN METHODS Male Wistar rats were divided in 4 different groups: control (CTRL), anthocyanin (ANT), streptozotocin (STZ) and streptozotocin+anthocyanin (STZ+ANT). After seven days of treatment with ANT (200mg/kg; oral), the rats were icv-STZ injected (3mg/kg), and four days later the behavior parameters were performed and the animals submitted to euthanasia. KEY FINDINGS A memory deficit was found in the STZ group, but ANT treatment showed that it prevents this impairment of memory (P<0.05). Our results showed a higher anxiety in the icv-STZ group, but treatment with ANT showed a per se effect and prevented the anxiogenic behavior induced by STZ. Our results reveal that the ANT treatment (100μM) tested displaces the specific binding of [(3)H] flunitrazepam to the benzodiazepinic site of GABAA receptors. AChE, Ca(+)-ATPase activities and NOx levels were found to be increased in HC and CC in the STZ group, which was attenuated by ANT (P<0.05). STZ decreased Na(+),K(+)-ATPase activity and ANT was able to prevent these effects (P<0.05). SIGNIFICANCE In conclusion, these findings demonstrated that ANT is able to regulate ion pump activity and cholinergic neurotransmission, as well as being able to enhance memory and act as an anxiolytic compound in animals with SDAT.

Aluminum-induced oxidative stress in cucumber.

Aluminum (Al) is one of the most abundant elements of the planet and exposure to this metal can cause oxidative stress and lead to various signs of toxicity in plants. Plants are essential organisms for the environment as well as food for humans and animals. The toxic effect of aluminum is the major cause of decreased crop productivity. Thus, the objective of the present study was to analyze the effects of aluminum on the activity of antioxidant enzymes such as catalase (CAT - E.C. 1.11.1.6), superoxide dismutase (SOD - E.C.1.15.1.1) and ascorbate peroxidase (APX - E.C. 1.11.1.11), and on lipid peroxidation, electrolyte leakage percentage (ELP) and chlorophyll and protein oxidation levels in Cucumis sativus L. (cv. Aodai). Seedlings were grown at different concentrations of aluminum ranging from 1 to 2000 microM for 10 days. The increase in ELP and H(2)O(2) production observed in the seedlings may be related to the decreased efficiency of the antioxidant system at higher aluminum concentrations. The antioxidant system was unable to overcome toxicity resulting in negative effects such as lipid peroxidation, protein oxidation and a decrease in the growth of Cucumis seedlings. Aluminum toxicity triggered alterations in the antioxidant and physiological status of growing cucumber seedlings.

Experimental infection with Rangelia vitalii in dogs: Acute phase, parasitemia, biological cycle, clinical-pathological aspects and treatment

Recently we conducted the molecular characterization of Rangelia vitalii, a protozoan with high pathogenicity for young dogs in southern Brazil. To date, the descriptions of the disease have been restricted to natural infection cases. Therefore, this study aimed to evaluate the parasitemia, biological cycles and clinical-pathological findings in dogs experimentally infected with R. vitalii in the acute phase of disease, and also aimed to test a therapeutic protocol based on the diminazene aceturate. For this study, we used 12 young dogs (females), separated into two groups. Group A was composed of healthy dogs, not-infected (n=5), and Group B consisted of animals infected with R. vitalii (n=7). After infection, the animals were monitored by blood smear examinations, which showed intra-erythrocytic forms of the parasite 5 days post-infection (PI). Parasitemia increased progressively in these animals and had the highest peak of circulating parasites between 9 and 11 days PI. Subsequently, the parasitemia reduced and the protozoan was seen inside the leukocytes in days 17, 19 and 21 PI. The most prominent clinical signs observed at the 20 day PI of experiment were lethargy, fever and anorexia. We observed a decrease of hematocrit of infected animals compared with not-infected dogs, featuring a moderate anemia. Pathological evaluation of one dog in Group B at day 21 PI revealed splenomegaly, hepatomegaly, lymphadenopathy, and hemorrhages at necropsy. Histological examination showed only follicular hyperplasia in the spleen and lymph nodes, and the etiologic agent in the vascular endothelium. At 21 days PI, it was performed the treatment of dogs in Group B (n=6) with a single dose of diminazene aceturate, which showed a curative efficacy of 100% in cleaning R. vitalii from blood of infected dogs.

The activity and expression of NTPDase is altered in lymphocytes of multiple sclerosis patients

BACKGROUND Multiple sclerosis (MS) is a demyelinating neurological disease, which is presumed to be a consequence of infiltrating lymphocytes that are autoreactive to myelin proteins. ATP and adenosine contribute to fine-tuning immune responses and NTPDase (CD39) and adenosine deaminase (ADA) are important enzymes in the control of the extracellular levels of these molecules at the site of inflammation. We evaluated the activity and expression of NTPDase and adenosine deaminase (ADA) activity in lymphocytes from patients with the relapsing-remitting form of MS (RRMS). METHODS This study involved 22 patients with RRMS and 22 healthy subjects as a control group. The lymphocytes were isolated from blood and separated on Ficoll density gradients and after isolation the NTPDase and ADA activities were determined. RESULTS The NTPDase activity and expression were increased in lymphocytes from RRMS patients when compared with the control group (p<0.05). In addition, a decrease in ADA activity was observed in lymphocytes from these patients when compared to the control group (p<0.05). CONCLUSIONS The regulation of ATP and adenosine levels by NTPDase and ADA activities may be important to preserve cellular integrity and to modulate the immune response in MS.

Acetylcholinesterase activity and lipid peroxidation in the brain and spinal cord of rats infected with Trypanosoma evansi

Neurological and locomotor clinical signs are described in animals infected with Trypanosoma evansi. These disturbances may be related to changes in the amount of acetylcholine (neurotransmitter) in the synaptic cleft. Therefore, changes in acetylcholinesterase (AChE) activity and lipid peroxidation in brain and spinal cord of T. evansi-infected rats were investigated. Each rat was intraperitoneally infected with 10(6) trypomastigotes kept in fresh (group A; n=13) and cryopreserved blood (group B; n=13). Thirteen served as uninfected (not-infected; group C). In days 4 and 30 post-infection (PI) the rats were anesthetized and subsequently decapitated to obtain the brain and the spinal cord (between vertebrae L1 and S2). The brain was removed and dissected (cerebellum, cerebral cortex, striatum and hippocampus) to measure the activity of AChE and lipid peroxidation, determined by TBARS levels. To verify if T. evansi was present in the central nervous system (CNS), brain structures of three rats of each group were processed by PCR T. evansi-specific. AChE activity was significantly increased in all brain structures and decrease in spinal cord in infected rats in 4 PI (P<0.05). The levels of TBARS were decreased in the brain structures, differently from spinal cord, which showed increased lipid peroxidation in 4 PI. The AChE activity in striatum, cerebral cortex, hippocampus and spinal cord reduced concomitantly with the increase of the enzyme in cerebellum of the infected rats (P<0.05), and the TBARS levels increased in cerebellum, striatum and spinal cord of infected rats compared to non-infected animals in 30 PI. The PCR was positive for T. evansi in all structures of the brain, confirming the presence of the parasite in the CNS. Based on the results, we conclude that the changes in AChE activity and lipid peroxidation in the CNS are induced by infection with T. evansi, suggesting that the parasite interferes with the cholinergic neurotransmission in this experimental condition.

Cytokines in rats experimentally infected with Trypanosoma evansi

The aim of this study was to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1) and interleukin 6 (IL-6) in the serum of rats experimentally infected with Trypanosoma evansi and to correlate these levels with hematological parameters. Initially, 48 rats (group T) were intraperitoneally inoculated with cryopreserved blood containing 1×10(6) trypomastigotes per animal. Twenty-eight animals (group C) were used as negative controls and received 0.2 mL of saline by the same route. The experimental groups were formed according to the time after infection and the degree of parasitemia as follows: four control subgroups (C3, C5, C10 and C20) with seven non-inoculated animals each and four test subgroups (T3, T5, T10 and T20) with 10 animals each inoculated with T. evansi. The blood samples were collected by cardiac puncture at days 3 (C3, T3), 5 (C5, T5), 10 (C10, T10) and 20 (C20, T20) post-infection (PI) to perform the complete blood count and the determination of IFN-γ, TNF-α, IL-1 and IL-6 levels using an ELISA quantitative sandwich. Infected rats showed normocytic normochromic anemia during the experimental period. T. evansi infection in rats caused a serum increase (P<0.01) of IFN-γ, TNF-α, IL-1 and IL-6 levels at days 3, 5, 10 and 20 PI compared to the controls. The multiple linear regressions showed a reduction of 24% in the hematocrit as a consequence of the increased IFN-γ, TNF-α and IL-1. Therefore, we conclude that the infection caused by T. evansi causes an increase in the pro-inflammatory cytokines. These results suggest a synergism among IL-1, TNF-α and IFN-γ contributing to the development of anemia. This increase is associated with the regulation of immune responses against the parasite.