Pathophysiological investigations, anxiolytic effects and interaction of a semisynthetic riparin with benzodiazepine receptors.

We have reported Riparin A as a promising antiparasitic molecule ​​against Leishmania amazonensis promastigotes. This work evaluated the acute oral toxicity of Riparin A and its anxiolytic effects using in vivo models and computational tools. Mice were submitted to acute oral toxicity tests (Guideline OECD 423). Later, anxiety assays with Riparin A (50, 100 and 200 mg/kg: elevated plus maze, light/dark box and marble burying) were performed. Theoretical calculations analyzed interaction of Riparin A with gamma-amino butyric acid (GABA) receptors. Only Riparin A at 2000 mg/kg alter body weight, food and water consumption and urine production after 7 and/or 14 days treatment and increased serum triglycerides. There was increase in the time spent in the open arms (TSOA) and number of transitions between compartments (NTC) and decrease in number of hidden balls (NHB) in Riparin A-treated animals at 200 mg/kg (P < 0.05), whose approximate ED50 was 283.1 (156.5-397.1) mg/kg. The functional amide of Riparin A interacted with the GABAA receptor mainly at subunits α2 and ß1 and presented strong interaction with the Asp68 residue, which is part of the pharmacophore group. Riparin A was toxically safe and pharmacologically active for anxiolytic purposes, revealed NOAEL of 200 mg/kg and probably interacts with Asp68 residues of benzodiazepine receptors by hydrogen bonds.

Counteracting effects on free radicals and histological alterations induced by a fraction with casearins.

Casearia sylvestris Swartz is a medicinal plant widely distributed in Brazil. It has anti-inflammatory, antiulcer and antitumor activities and is popularly used to treat snakebites, wounds, diarrhea, flu and chest colds. Its leaves are rich in oxygenated tricyclic cis-clerodane diterpenes, particulary casearins. Herein, we evaluated the antioxidant activities of a fraction with casearins (FC) isolated from C. sylvestris and histological changes on the central nervous system and livers of Mus musculus mice. Firstly, in vitro studies (0.9, 1.8, 3.6, 5.4 and 7.2 µg/mL) revealed EC50 values of 3.7, 6.4 and 0.16 µg/mL for nitrite, hydroxyl radical and TBARS levels, respectively. Secondly, FC (2.5, 5, 10 and 25 mg/kg/day) was intraperitoneally administered to Swiss mice for 7 consecutive days. Nitrite levels in the hippocampus (26.2, 27.3, 30.2 and 26.6 µM) and striatum (26.3, 25.4, 34.3 and 27.5 µM) increased in all treated animals (P < 0.05). Lower doses dropped reduced glutathione, catalase and TBARS levels in the hippocampus and striatum. With the exception of this reduction in TBARS formation, FC displayed only in vitro antioxidant activity. Animals exhibited histological alterations suggestive of neurotoxicity and hepatotoxicity, indicating the need for precaution regarding the consumption of medicinal formulations based on Casearia sylvestris.

The effect of natural and organophilic palygorskite on skin wound healing in rats

In view of growing interest in natural treatments, clays would appear to be a good alternative for speeding up the healing process during the treatment of wounds. Of the various clays, palygorskite, a clay from the Brazilian State of Piauí, composed of silicon and aluminum, has shown itself to be pharmaceutically useful as a healing agent. The aim of this article is to evaluate the effect on the healing of wounds of Piauí palygorskite, both in its natural state and when organophilic, by way of comparative analysis of macroscopic and histological tests on skin wounds in adult male and female two-month-old Wistar rats. To this end, a circular trichotomy of the dorsal cornus of the rats was carried out to confirm the effects of treatments involving 0.9% saline solution, collagenase, natural palygorskite, organophilic palygorskite with cetyltrimethylammonium chloride, and organophilic palygorskite with alkyldimethylbenzylammonium chloride. The testing of all the clays involved microbiological evaluation using the depth of plaque and surface striation methods, along with post-treatment macroscopic analysis of skin wounds by way of organoleptics, pachymetry and histological analysis. Microbiological evaluation revealed the need for sterilization of the clay prior to incorporation in the pharmaceutical form. Macroscopic analysis suggests that healing of the wounded area occurred, and histological analysis showed the beneficial effect of the topical use of clay material. Our data suggest that palygorskite may be more powerful than other healing agents, although, on completing treatment, all the animals studied showed the same degree of tissue repair.

Devido ao crescente interesse da população pelos tratamentos naturais, as argilas representam uma boa alternativa para a aceleração da cicatrização durante o tratamento de feridas. Dentre as argilas, a paligorsquita, uma argila piauiense, devido à sua composição com silício e alumínio, demonstra certa aplicabilidade farmacêutica como agente cicatrizante. O objetivo deste artigo é avaliar a ação cicatrizante da paligorsquita piauiense em sua forma natural e organofilizadas por meio da análise comparativa da macroscopia e dos exames histológicos em feridas cutâneas de ratos machos e fêmeas Wistar adultos com 2 meses de idade. Para tanto, foram realizadas tricotomia circular no corno dorsal dos ratos para verificar os efeitos dos tratamentos realizados com solução salina 0,9%, colagenase, paligorsquita natural, paligorsquita organofilizada por cloreto de cetiltrimetilamônio e paligorsquita organofilizada por cloreto de alquildimetilbenzilamônio. Para todas as argilas testadas foi feita a avaliação microbiológica pelo método de plaqueamento em profundidade e do método de estrias em superfície, bem como foi realizada após tratamento, a análise macroscópica das feridas cutâneas por meio organoléptico, medição em paquímetro e análise histológica. Por meio da avaliação microbiológica foi detectada a necessidade de esterilização da argila para posterior incorporação na forma farmacêutica. A análise macroscópica sugere que houve cicatrização da área lesionada, bem como a análise histológica demonstrou efeito benéfico após o uso tópico do material argiloso. Nossos dados sugerem que a paligorsquita pode exercer um maior efeito cicatrizante em relação aos demais tratamentos, embora após o término deste tratamento, todos os animais analisados apresentaram a mesma reparação tecidual.

Evaluation of possible antioxidant and anticonvulsant effects of the ethyl acetate fraction from Platonia insignis Mart. (Bacuri) on epilepsy models.

The aim of present study was to examine the effects of the ethyl acetate fraction (EAF) from Platonia insignis on lipid peroxidation level, nitrite formation, and superoxide dismutase and catalase activities in rat striatum prior to pilocarpine-induced seizures as well as to explore its anticonvulsant activity in adult rats prior to pentylenetetrazole (PTZ)- and picrotoxin (PIC)-induced seizures. Wistar rats were treated with vehicle, atropine (25mg/kg), EAF (0.1, 1, and 10mg/kg), pilocarpine (400mg/kg, P400 group), PTZ (60 mg/kg, PTZ group), PIC (8 mg/kg, PIC group), atropine+P400, EAF+P400, EAF+PTZ, or EAF+PIC. Significant decreases in number of crossings and rearings were observed in the P400 group. The EAF 10+P400 group also had significant increases in these parameters. In addition, in rats treated with P400, there were significant increases in lipid peroxidation and nitrite levels; however, there were no alterations in SOD and catalase activities. In the EAF 10+P400 group, lipid peroxidation and nitrite levels significantly decreased and SOD and catalase activities significantly increased after pilocarpine-induced seizures. Additionally, effects of the EAF were evaluated in PTZ and PIC models. EAF did not increase the latency to development of convulsions induced with PTZ and PIC at the doses tested. Our findings strongly support the hypothesis that EAF does not have anticonvulsant activity in the different models of epilepsy studied. Our results indicate that in the in vivo model of pilocarpine-induced seizures, EAF has antioxidant activity, but not anticonvulsant properties at the doses tested.

Oxidative stress in rat striatum after pilocarpine-induced seizures is diminished by alpha-tocopherol.

Alpha-tocopherol has numerous nonenzymatic actions and is a powerful liposoluble antioxidant. The objective of the present study was to evaluate the neuroprotective effects of alpha-tocopherol in rats against oxidative stress caused by pilocarpine-induced seizures. Wistar rats were intraperitoneally treated with 0.9% saline (control group), alpha-tocopherol (200 mg/kg, alpha-tocopherol group), pilocarpine (400 mg/kg, pilocarpine group), or the combination of alpha-tocopherol (200 mg/kg) and pilocarpine (400 mg/kg, i.p.; alpha-tocopherol plus pilocarpine group). After the treatments, all groups were observed for 24 h. The superoxide dismutase (Mn-SOD) and catalase activities, lipid peroxidation and nitrite concentrations were measured using spectrophotometrically methods. To clarify the mechanism of alpha-tocopherol on oxidative stress in pilocarpine model, Western blot analysis of Mn-SOD and catalase in rat striatum were performed. In the pilocarpine group, rats showed a significant increase in lipid peroxidation and nitrite levels. However, there were no alterations on Mn-SOD activity. On the other hand, the catalase activity augmented in pilocarpine group. In the alpha-tocopherol and pilocarpine co-administered rats, antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content and increased the Mn-SOD and catalase activities in rat striatum after seizures. Pilocarpine, alpha-tocopherol plus pilocarpine and alpha-tocopherol groups did not affect of the Mn-SOD and catalase mRNA or protein levels. Our findings strongly support the hypothesis that oxidative stress occurs in striatum during pilocarpine-induced seizures, indicating that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, which implies that strong protective effect could be achieved using alpha-tocopherol.

Estudos comportamentais e das alterações histopatológicas em camundongos pré-tratados com Bellis perennis no modelo de convulsão induzido por pilocarpina / Behavioral studies and histopathological changes in mice pretreated with Bellis perennis in pilocarpine-induced seizures

The aim of this study was to investigate the potential neuroprotective and anticonvulsant effects of ethanolic extract from flowers (EEF) of B. perrenis in adult Swiss mice (2 months old) after seizures induced by pilocarpine. The animals were divided into 8 groups. The first group was treated with vehicle (0.05 percent Tween 80 dissolved in 0.9 percent saline) and the second with pilocarpine (400 mg/kg, P400 group). The third, fourth and fifth group were pretreated with EEF (50, 100 or 150 mg/kg) and 30 min later received P400 (EEF 50, EEF 100 or EEF 150 plus P400 groups), respectively. In turn, the remaining groups were treated with EEF alone (50, 100 or 150 mg/kg EEF 50, EEF 100 or EEF 150 groups), respectively. After treatment, the groups were observed for 24 h and then euthanized and their brains removed for histopathological analysis. All P400 group animals showed seizures that progressed to status epilepticus. Pre-treatment with EEF produced a significant reduction in those indices. P400 and EEF 50 plus P400 groups showed 87.5 percent and 37.5 percent of animals with brain damage in the hippocampus, respectively. In P400 group, the damage rate in striatum was 75 percent. In turn, this region has seen a reduction of 46.99 percent neuronal damage of those of EEF 50 plus P400 group. According to our results we suggest that the EEF may modulate epileptogenesis and promote anticonvulsant and neuroprotective mechanisms in model of seizures induced by pilocarpine.

O objetivo desse estudo foi investigar o potencial efeito neuroprotetor e anticonvulsivante do extrato etanólico das flores de B. perrenis (EEF) em camundongos Swiss adultos (2 meses) após convulsão induzida por pilocarpina. Os animais foram divididos em 8 grupos. O primeiro grupo foi tratado com veículo (Tween 80 0,05 por cento dissolvido em salina 0,9 por cento) e o segundo com pilocarpina (400 mg/kg, grupo P400). Já o terceiro, quarto e quinto grupo foram tratados com EEF (50, 100 ou 150 mg/kg), e 30 min depois receberam P400 (grupos EEF 50, EEF 100 ou EEF 150 plus P400), respectivamente. Por sua vez, os demais grupos foram tratados somente com EEF (50, 100 ou 150 mg/kg; grupos EEF 50, EEF 100 ou EEF 150), respectivamente. Após os tratamentos, os grupos foram observados durante 24 h e em seguida eutanasiados e seus cérebros removidos para as análises histopatológicas. Todos os animais do grupo P400 apresentaram convulsões que progrediram para o estado de mal epiléptico. O pré-tratamento com EEF produziu uma redução significativa nesses índices. Os grupos P400 e EEF 50 plus P400 apresentaram 87,5 por cento e 37,5 por cento de animais com lesão cerebral no hipocampo, respectivamente. No corpo estriado dos animais do grupo P400 houve um comprometimento de 75 por cento. Por sua vez, nessa região foi vista uma redução de 46,99 por cento nesse comprometimento nos animais do grupo EEF 50 plus P400. De acordo com nossos resultados podemos sugerir que o EEF pode modular a epileptogênese e promover ação neuroprotetora e anticonvulsivante no modelo das convulsões induzidas por pilocarpina.

Avaliação do potencial neuroprotetor do óleo essencial de Citrus limon em hipocampo e corpo estriado de camundongos após convulsões induzidas pela pilocarpina / Evaluation of neuroprotective potential of Citrus limon essential oil in hippocampus and striatum of mice after pilocarpine-induced seizures

The seizures can produce neuronal damage in several brain structures. The aim of this study was to investigate the potential neuroprotective effect of essential oil of Citrus limon (EOCL) on the histopathological changes observed in the hippocampus and striatum of mice after seizures induced by pilocarpine. Adult Swiss mice were 2 months old. The animals were divided into four groups. The first group was treated with 0.05 percent Tween 80 (control group) and the second with pilocarpine (400 mg/kg group P400). The third and fourth group were treated with EOCL (150 mg/kg) and 30 min after received P400 (P400 +/- EOCL group) or 0.05 percent Tween 80, respectively. After treatment, all groups were observed for 24 h, then sacrificed and their brains removed for histopathological analysis. The group P400, presented with seizures that progressed to status epilepticus in 75 percent of animals. Pretreatment with OECL produced a 25 percent reduction in this index. Groups P400 and P400 + EOCL showed 83.33 percent and 25 percent of animals with brain damage in the hippocampus, respectively. In the striatum of group P400 was a compromise of 75 percent. In turn, in the striatal region of group EOCL P400 + was seen a decrease of 58.34 percent in this neuronal damage. The seizures induced by pilocarpine are installed by the cholinergic system and produce brain damage. According to our results we suggest that the EOCL may modulate epileptogenesis and promote neuroprotective effects during the seizures in the model investigated.

As convulsões podem produzir danos neuronais em diversas estruturas cerebrais. O objetivo desse estudo foi investigar o potencial efeito neuroprotetor do óleo essencial de Citrus limon (OECL) nas alterações histopatológicas observadas no hipocampo e corpo estriado de camundongos após convulsão induzida por pilocarpina. Foram utilizados camundongos Swiss adultos com 2 meses de idade. Os animais foram divididos em 4 grupos. O primeiro grupo foi tratado com Tween 80 0,05 por cento (grupo controle) e o segundo com pilocarpina (400 mg/kg, grupo P400). Já o terceiro e quarto grupo foram tratados com OECL (150 mg/kg), e 30 min depois receberam P400 (grupo OECL + P400) ou Tween 80 0,05 por cento 0.9 por cento (grupo OECL), respectivamente. Após os tratamentos, todos os grupos foram observados durante 24 h e em seguida sacrificados e seus cérebros removidos para as análises histopatológicas. O grupo P400, apresentou convulsões que progrediram para o estado epiléptico em 75 por cento dos animais. O pré-tratamento com OECL produziu uma redução de 25 por cento nesse índice. Os grupos P400 e OECL + P400 apresentaram 83,33 por cento e 25 por cento de animais com lesão cerebral no hipocampo, respectivamente. No corpo estriado dos animais do grupo P400 houve um comprometimento de 75 por cento. Por sua vez, na região estriatal dos animais do grupo OECL + P400 foi visto uma redução de 58,34 por cento nesse comprometimento. As convulsões induzidas pela pilocarpina são instaladas pelo sistema colinérgico e produzem dano cerebral. De acordo com nossos resultados podemos sugerir que o OECL pode modular a epileptogênese e promover ação neuroprotetora durante as convulsões no modelo investigado.

Lipoic acid inhibits caspase-dependent and -independent cell death pathways and is neuroprotective against hippocampal damage after pilocarpine-induced seizures.

Alpha-lipoic acid has some neuroprotective properties, but this action has not been investigated in models of epilepsy. The aim of the present study was to investigate the protective efficacy of α-lipoic acid (lipoic acid) against pilocarpine-induced cell death through the caspase-dependent or -independent mitochondrial apoptotic pathways. Wistar rats were injected intraperitoneally with 0.9% saline (control group), pilocarpine (400 mg/kg, pilocarpine group) alone, or α-lipoic acid (20 mg/kg) in association with pilocarpine (400 mg/kg) 30 min before administration of α-lipoic acid. After the treatments all groups were observed for 24 h. Cell death was reduced in lipoic acid-treated rats. Cytosolic translocation of cytochrome c and subsequent activation of caspase-3 were reduced by lipoic acid treatment. AIF nuclear translocation and subsequent large-scale DNA fragmentation were also decreased in lipoic acid-treated rats. Our study suggests that lipoic acid inhibits both caspase-dependent and -independent apoptotic pathways and may be neuroprotective against hippocampal damage during pilocarpine-induced seizures.

Neuronal damage and memory deficits after seizures are reversed by ascorbic acid?

The objective of the present study was to evaluate the neuroprotective effects of ascorbic acid (AA) in rats, against the neuronal damage and memory deficit caused by seizures. Wistar rats were treated with 0.9% saline (i.p., control group), ascorbic acid (500 mg/kg, i.p., AA group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of ascorbic acid (500 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before of administration of ascorbic acid (AA plus pilocarpine group). After the treatments all groups were observed for 24 h. Pilocarpine group presented seizures which progressed to status epilepticus in 75% of the animals. Pretreatment with AA led to a reduction of 50% of this rate. Results showed that pretreatment with AA did not alter reference memory when compared to a control group. In the working memory task, we observed a significant day's effect with important differences between control, pilocarpine and AA plus pilocarpine groups. Pilocarpine and AA plus pilocarpine groups had 81 and 16% of animals with brain injury, respectively. In the hippocampus of pilocarpine animals, it was detected an injury of 60%. As for the animals tested with AA plus pilocarpine, the hippocampal region of the group had a reduction of 43% in hippocampal lesion. Our findings suggest that seizures caused cognitive dysfunction and neuronal damage that might be related, at least in part, to the neurological problems presented by epileptic patients. AA can reverse cognitive dysfunction observed in rats with seizures as well as decrease neuronal injury in rat hippocampus.

Neuronal damage and memory deficits after seizures are reversed by ascorbic acid? / O dano neuronal e o déficit de memória após convulsões são revertidos pelo ácido ascórbico?

The objective of the present study was to evaluate the neuroprotective effects of ascorbic acid (AA) in rats, against the neuronal damage and memory deficit caused by seizures. Wistar rats were treated with 0.9 percent saline (i.p., control group), ascorbic acid (500 mg/kg, i.p., AA group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of ascorbic acid (500 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before of administration of ascorbic acid (AA plus pilocarpine group). After the treatments all groups were observed for 24 h. Pilocarpine group presented seizures which progressed to status epilepticus in 75 percent of the animals. Pretreatment with AA led to a reduction of 50 percent of this rate. Results showed that pretreatment with AA did not alter reference memory when compared to a control group. In the working memory task, we observed a significant day's effect with important differences between control, pilocarpine and AA plus pilocarpine groups. Pilocarpine and AA plus pilocarpine groups had 81 and 16 percent of animals with brain injury, respectively. In the hippocampus of pilocarpine animals, it was detected an injury of 60 percent. As for the animals tested with AA plus pilocarpine, the hippocampal region of the group had a reduction of 43 percent in hippocampal lesion. Our findings suggest that seizures caused cognitive dysfunction and neuronal damage that might be related, at least in part, to the neurological problems presented by epileptic patients. AA can reverse cognitive dysfunction observed in rats with seizures as well as decrease neuronal injury in rat hippocampus.

O objetivo do presente estudo foi avaliar o efeito neuroprotetor do ácido ascórbico (AA), contra o dano neuronal e o déficit de memória em ratos causados pelas convulsões. Ratos Wistar foram tratados com solução salina a 0,9 por cento (i.p., grupo controle), ácido ascórbico (500 mg/kg, i.p., grupo AA), pilocarpina (400 mg/kg, i.p., grupo pilocarpina), e a associação de ácido ascórbico (500 mg/kg, i.p.) com pilocarpina (400 mg/kg, i.p.), 30 min após a administração de ácido ascórbico (AA + pilocarpina grupo). Após os tratamentos todos os grupos foram observados durante 24 h. O grupo pilocarpina apresentou crises convulsivas que evoluíram para o estado de mal epiléptico em 75 por cento dos animais. O pré-tratamento com AA produz uma redução de 50 por cento nesta taxa. Os resultados mostraram que o pré-tratamento com AA não alterou a memória em relação ao controle. No teste de memória, observou-se um efeito significativo nos dias avaliados entre os grupos controle, pilocarpina e AA + pilocarpina. 81 e 16 por cento dos animais dos grupos AA + pilocarpina e pilocarpina apresentaram danos cerebrais, respectivamente. No hipocampo dos animais do grupo pilocarpina, que foi detectada uma lesão de hipocampal de 60 por cento. Quanto aos animais do grupo AA + pilocarpina, a região do hipocampo apresentou uma redução de 43 por cento na extensão da lesão no hippocampo. Nosso resultados sugerem que as convulsões produzem disfunção cognitiva e dano neuronal que podem estar relacionados, pelo menos em parte, aos problemas neurológicos apresentados pelos pacientes epilépticos. O ácido ascórbico pode reverter essa disfunção cognitiva observado em ratos convulsivos, bem como reduz o desenvolvimento da lesão neuronal no hipocampo de ratos.

Inhibitory action of antioxidants (ascorbic acid or alpha-tocopherol) on seizures and brain damage induced by pilocarpine in rats.

Temporal lobe epilepsy is the most common form of epilepsy in humans. Oxidative stress is a mechanism of cell death induced by seizures. Antioxidant compounds have neuroprotective effects due to their ability to inhibit free radical production. The objectives of this work were to comparatively study the inhibitory action of antioxidants (ascorbic acid or alpha-tocopherol) on behavioral changes and brain damage induced by high doses of pilocarpine, aiming to further clarify the mechanism of action of these antioxidant compounds. In order to determinate neuroprotective effects, we studied the effects of ascorbic acid (250 or 500 mg/kg, i.p.) and alpha-tocopherol (200 or 400 mg/kg, i.p.) on the behavior and brain lesions observed after seizures induced by pilocarpine (400 mg/kg, i.p., P400 model) in rats. Ascorbic acid or alpha-tocopherol injections prior to pilocarpine suppressed behavioral seizure episodes. These findings suggested that free radicals can be produced during brain damage induced by seizures. In the P400 model, ascorbic acid and alpha-tocopherol significantly decreased cerebral damage percentage. Antioxidant compounds can exert neuroprotective effects associated with inhibition of free radical production. These results highlighted the promising therapeutic potential of ascorbic acid and alpha-tocopherol in treatments for neurodegenerative diseases.

Alterations on monoamines concentration in rat hippocampus produced by lipoic acid.

The purposes of the present study were to verify monoamines (dopamine (DA), norepinephrine (NE), serotonin (5-HT)), and their metabolites (3,4-hydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA)) contents in rat hippocampus after lipoic acid (LA) administration. Wistar rats were treated with 0.9% saline (i.p., control group) and LA (10, 20 or 30 mg/kg, i.p., LA10, LA20 and LA30 groups, respectively). After the treatments all groups were observed for 24 h. The NE and DA levels were increased only in 20 mg/kg dose of LA in rat hippocampus. Serotonin content and in their metabolite 5-HIAA levels was decreased in same dose of LA. On the other hand, in DOPAC and HVA levels did not show any significant change. The alterations in hippocampal monoamines can be suggested as a possible of brain mechanism of action from this antioxidant. The outcome of the study may have therapeutic implications in the treatment of neurodegenerative diseases.

Inhibitory action of antioxidants (ascorbic acid or α-tocopherol) on seizures and brain damage induced by pilocarpine in rats / Ação inibitória de antioxidantes (ácido ascórbico e α-tocoferol) nas convulsões e dano cerebral em ratos induzidos pela pilocarpina

Temporal lobe epilepsy is the most common form of epilepsy in humans. Oxidative stress is a mechanism of cell death induced by seizures. Antioxidant compounds have neuroprotective effects due to their ability to inhibit free radical production. The objectives of this work were to comparatively study the inhibitory action of antioxidants (ascorbic acid or α-tocopherol) on behavioral changes and brain damage induced by high doses of pilocarpine, aiming to further clarify the mechanism of action of these antioxidant compounds. In order to determinate neuroprotective effects, we studied the effects of ascorbic acid (250 or 500 mg/kg, i.p.) and α-tocopherol (200 or 400 mg/kg, i.p.) on the behavior and brain lesions observed after seizures induced by pilocarpine (400 mg/kg, i.p., P400 model) in rats. Ascorbic acid or α-tocopherol injections prior to pilocarpine suppressed behavioral seizure episodes. These findings suggested that free radicals can be produced during brain damage induced by seizures. In the P400 model, ascorbic acid and α-tocopherol significantly decreased cerebral damage percentage. Antioxidant compounds can exert neuroprotective effects associated with inhibition of free radical production. These results highlighted the promising therapeutic potential of ascorbic acid and α-tocopherol in treatments for neurodegenerative diseases.

A epilepsia de lobo temporal é a mais comum forma de epilepsia em humanos. O estresse oxidativo é um dos mecanismos de morte celular induzida pelas crises convulsivas. Os compostos antioxidantes apresentam efeitos neuroprotetores devido à sua capacidade de inibir a produção de radicais livres. Os objetivos do presente trabalho foram estudar de forma comparativa a ação inibitória de antioxidantes (ácido ascórbico e α-tocoferol) sobre as alterações comportamentais e histopatológicas no hipocampo de ratos após convulsões induzidas pela pilocarpina. A fim de determinar os efeitos neuroprotetores destas drogas, o presente trabalho estudou os efeitos do ácido ascórbico (250 ou 500 mg/kg, i.p.) e do α-tocoferol (200 ou 400 mg/kg, i.p.) sobre o comportamento e as lesões cerebrais observados após convulsões induzidas pela pilocarpina (400 mg/kg, i.p., P400), em ratos. As injeções de ácido ascórbico ou α-tocoferol antes da administração de pilocarpina reduzem o número de animais que convulsionam. Estes achados sugerem que os radicais livres podem induzir o desenvolvimento de lesão cerebral durante as crises epilépticas. No modelo P400, o ácido ascórbico e o α-tocoferol, diminuem significativamente os danos cerebrais. Os compostos antioxidantes podem exercer efeitos neuroprotetores, e esses resultados podem estar associados à inibição da produção de radicais livres. Estes resultados sugerem um promissor potencial terapêutico tanto para o ácido ascórbico quanto para o α-tocoferol no tratamento de doenças neurodegenerativas.

Alterations on monoamines concentration in rat hippocampus produced by lipoic acid / Alterações na concentração de monoaminas no hipocampo de ratos produzidas pelo ácido lipóico

The purposes of the present study were to verify monoamines (dopamine (DA), norepinephrine (NE), serotonin (5-HT)), and their metabolites (3,4-hydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA)) contents in rat hippocampus after lipoic acid (LA) administration. Wistar rats were treated with 0.9 percent saline (i.p., control group) and LA (10, 20 or 30 mg/kg, i.p., LA10, LA20 and LA30 groups, respectively). After the treatments all groups were observed for 24 h. The NE and DA levels were increased only in 20 mg/kg dose of LA in rat hippocampus. Serotonin content and in their metabolite 5-HIAA levels was decreased in same dose of LA. On the other hand, in DOPAC and HVA levels did not show any significant change. The alterations in hippocampal monoamines can be suggested as a possible of brain mechanism of action from this antioxidant. The outcome of the study may have therapeutic implications in the treatment of neurodegenerative diseases.

O objetivo do presente estudo foi verificar a concentração das monoaminas (dopamina (DA), norepinefrina (NA), serotonina (5-HT)), e seus metabólitos (ácido 3,4-hidroxifenil (DOPAC), ácido homovanílico (HVA) e 5 ácido hydroxiindolacético (5-HIAA)) no hipocampo de ratos após administração do ácido lipóico (AL). Ratos Wistar foram tratados com solução salina 0,9 por cento (i.p., grupo controle) e AL (10, 20 ou 30 mg/kg, i.p., AL10, AL20 e AL30 grupos, respectivamente). Após os tratamentos todos os grupos foram observados durante 24 h. O conteúdo de DA no hipocampo de ratos foi aumentado apenas com AL na dose de 20 mg/kg dose. A concentração de serotonina e do seu metabólito 5-HIAA também foi diminuída com esta dose de AL. Por outro lado, os níveis de DOPAC e de HVA não mostrram nenhuma mudança significativa. As alterações na concentração das monoaminas hipocampais podem ser sugeridas como um possível mecanismo de ação cerebral deste antioxidante. O resultado do estudo pode ter implicações terapêuticas no tratamento de doenças neurodegenerativas.

Vitamin E ameliorates high dose trans-dehydrocrotonin-associated hepatic damage in mice.

trans-Dehydrocrotonin (t-DCTN), the diterpenoid from Croton cajucara Bentham, exhibits hypoglycemic and hypolipidemic activities, but in high doses is associated with a discrete hepatotoxicity. In the search for measures to mitigate this, pretreatment with the antioxidants N-acetylcysteine and vitamin E has been examined. Mice that received a high dose t-DCTN (100 mg/kg) manifested hepatic damage, as evidenced by significant elevations in serum ALT and AST, and hepatic GSH, and histological alterations, which could be obliterated by pretreatment with vitamin E, but not with N-acetylcysteine, possibly by creating an effective antioxidant balance.

Lipoic acid blocks seizures induced by pilocarpine via increases in delta-aminolevulinic dehydratase and Na+, K+-ATPase activity in rat brain.

In the present study we investigated the effects of lipoic acid (LA) on delta-aminolevulinic dehydratase (delta-ALA-D) and Na(+), K(+)-ATPase activities in rat brain after seizures induction by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), lipoic acid (10mg/kg, i.p., LA group), pilocarpine (400mg/kg, i.p., pilocarpine group), or the combination of LA (10mg/kg, i.p.) with pilocarpine (400mg/kg, i.p.), 30 min before administration of LA (LA plus pilocarpine group). After the treatments all groups were observed for 1h. The enzyme activities (delta-ALA-D and Na(+), K(+)-ATPase) were measured using spectrophotometric methods, and the results were compared with that obtained from saline and pilocarpine-treated animals. Neuroprotective effects of LA against seizures were evaluated based on those enzyme activities. The pilocarpine group showed a reduction in delta-ALA-D and Na(+), K(+)-ATPase activities after seizures. In turn, LA plus pilocarpine abolished the appearance of seizures and reversed the decreased in delta-ALA-D and Na(+), K(+)-ATPase activities produced by seizures, when compared to the pilocarpine seizing group. The results from the present study demonstrate that preadministration of LA abolished seizure episodes induced by pilocarpine in rat, probably by increasing delta-ALA-D and Na(+), K(+)-ATPase activities in rat brain during seizures.

Effects of ubiquinone on hydroperoxide concentration and antioxidant enzymatic activities in the rat hippocampus during pilocarpine-induced seizures.

Recent researches have shown that antioxidant compounds may have certain neuroprotective effect against the neurotoxicity of seizures at cellular level. Ubiquinone (UQ), an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. The objective of the present study was to evaluate the neuroprotective effects of UQ in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with either 0.9% saline (i.p., control group), UQ (5, 10 or 20 mg/kg, i.p., UQ5, UQ10 and UQ20 groups), pilocarpine (400 mg/kg, i.p., P400 group), or co-administration of pilocarpine with UQ group rats 30 min prior to UQ administration. After the treatments all groups were observed for 24 h. The antioxidant enzymatic activities as well as the hydroperoxide concentrations were measured using spectrophotometric methods and the results were analyzed. In pilocarpine group there was a significant increase in hydroperoxides concentration and glutathione peroxidase activity. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the hydroperoxide content and increased the superoxide dismutase, catalase and glutathione peroxidase activities in rat hippocampus during seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, which indicates that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences. Our result also suggests that ubiquinone can exert significant neuroprotective effects that might be useful in the treatment of neurodegenerative diseases.

Oxidative stress in rat hippocampus caused by pilocarpine-induced seizures is reversed by buspirone.

Temporal lobe epilepsy is the most common form of epilepsy in humans. Oxidative stress is a mechanism of cell death induced by seizures. Buspirone presents anxyolitic and antidepressant effects due to their ability to stimulate 5-HT(1A) receptor. We studied the buspirone effects on oxidative stress in rat hippocampus after seizures and status epilepticus (SE) induced by pilocarpine. In pilocarpine group there was a significant increase in lipid peroxidation and nitrite levels. However, no alteration was observed in superoxide dismutase and catalase activities. Buspirone pretreatment produces significantly reduction of the lipid peroxidation level (60%) and nitrite content (44%) as well as increased the superoxide dismutase (47%) and catalase (40%) activities in rat hippocampus after seizures, when compared with the pilocarpine group. The intraperitoneal injection of buspirone prior to pilocarpine suppressed the behavioral seizure occurrence. According to our results, the oxidative stress is present during seizures. Buspirone exerted anticonvulsant effects associated with the inhibition of the development of oxidative stress. These results suggest a therapeutic use potential of buspirone in epilepsy treatment.

Ações neuroprotetoras da vitamina C no corpo estriado de ratos após convulsões induzidas pela pilocarpina / Neuroprotective actions of vitamin C in rat striatum after pilocarpine-induced seizures

CONTEXTO: As convulsões podem produzir danos neuronais em diversas áreas e, especialmente, nas estruturas límbicas. OBJETIVOS: O objetivo do presente trabalho foi estudar os efeitos neuroprotetores da vitamina C nas alterações histopatológicas observadas no corpo estriado de ratos convulsivos. MATERIAL E MÉTODOS: Foram utilizados ratos Wistar adultos. Os animais foram divididos em quatro grupos. O primeiro grupo foi tratado com salina 0,9 por cento (grupo controle) e o segundo, com pilocarpina (400 mg/kg, grupo P400). Já o terceiro e o quarto grupo foram tratados com vitamina C (250 mg/kg), e, 30 minutos depois, receberam P400 (grupo VIT C + P400) ou solução salina 0,9 por cento (grupo VIT C), respectivamente. Após os tratamentos, todos os grupos foram observados por 24 horas e, em seguida, sacrificados e seus cérebros removidos para as análises histopatológicas. RESULTADOS: O grupo P400 apresentou convulsões que progrediram para o estado epiléptico em 75 por cento dos animais. O pré-tratamento com vitamina C produziu uma redução de 35 por cento nesse índice. Os grupos P400 e VIT C + P400 apresentaram 80 por cento e 20 por cento de animais com lesão cerebral, respectivamente. No corpo estriado dos animais do grupo P400, houve um comprometimento de 50 por cento. Por sua vez, na região estriatal dos animais do grupo VIT C + P400 foi vista uma redução de 40 por cento nesse comprometimento. DISCUSSÃO: As convulsões induzidas pela pilocarpina são instaladas pelo sistema colinérgico e propagadas pela produção de radicais livres e pelo sistema glutamatérgico, resultado no desenvolvimento de dano cerebral. As drogas antioxidantes podem apresentar um potencial terapêutico para pacientes epilépticos na proteção contra as lesões cerebrais por meio da remoção desses radicais livres formados. Acredita-se, assim, que a vitamina C pode influenciar a epileptogênese e promover ações neuroprotetoras durante as convulsões.

BACKGROUND: Seizures may produce neuronal damage in several areas and especially in limbic structures. OBJECTIVES: This study aimed to evaluate the neuroprotective effects of vitamin C in the histopathological changes observed in rat striatum after seizures. MATERIAL AND METHODS: Healthy Wistar rats were divided into four groups. The first group was treated with 0.9 percent saline (control group) and the second one with pilocarpine (400 mg/kg, P400 group). Third and fourth groups were treated with vitamin C (250 mg/kg), 30 minutes before receiving P400 (P400 + VIT C group) or 0.9 percent saline (VIT C group), respectively. After the treatments, all groups were observed for 24 hours, sacrificed and dissected out to remove their brains for histopathological analysis. RESULTS: The group P400 presented seizures that progressed to status epilepticus in 75 percent of the animals. Pretreatment with vitamin C produced a 35 percent reduction in this index. P400 and P400 + VIT C groups revealed 80 percent and 20 percent of animals with brain injury, respectively. In P400 group, lesion severity of the striatum was 50 percent. In turn, in striatal region of animals treated with P400 + VIT C group, we detected a reduction of 40 percent in the severity degree. DISCUSSION: Pilocarpine-induced seizures are installed by the cholinergic system and propagated by free radicals and by glutamatergic system, leading to brain damage. The antioxidant drugs may have therapeutic potential for epileptic patients to protect against brain injure through removing free radicals produced, suggesting that vitamin C may influence epileptogenesis and promote neuroprotective actions during seizures.

Gastroprotective activity of isopulegol on experimentally induced gastric lesions in mice: investigation of possible mechanisms of action.

The present study investigated whether isopulegol, a monoterpene present in essential oils of several aromatic plants, would be able to promote some gastroprotective effect and also verified the possible mechanisms involved in this action. For this study, ethanol- and indomethacin-induced gastric ulcer models in mice and histopathological assessment were used. The roles of NO, sulfhydryls (glutathione, GSH), ATP-sensitive K(+) channels (K(ATP) channels), and prostaglandins were also investigated. Isopulegol exhibited a dose-related gastroprotective effect against ethanol-induced lesions, while the pretreatment with glibenclamide and indomethacin [but not with N(G)-nitro-L-arginine methyl ester] were able to reverse this action. The pretreatment with isopulegol also restored GSH levels to normal levels and exhibited dose-related gastroprotective effect against indomethacin-induced ulcer. The results suggested that isopulegol presents significant gastroprotective effects in both ethanol- and indomethacin-induced ulcer models, which appear to be mediated, at least in part, by endogenous prostaglandins, K(ATP) channel opening, and antioxidant properties.