RESUMO
BACKGROUND: Parkinson's disease (PD) is a chronic neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the nigrostriatal pathway. Even with scientific and technological advances, the therapeutic approaches used for the treatment of PD have shown to be largely ineffective in controlling the progression of symptoms in the long term. There is a growing demand for the development of novel therapeutic strategies for PD treatment. Different herbs and supplements have been considered as adjuvant to treat the symptoms of Parkinsonism. The carrot is one of the most consumed vegetable species worldwide, and its root is known for its content of anthocyanins, which possess antioxidant and antiinflammatory properties. This study evaluated the neuroprotective effect of purple carrot extract (CAR) in rats on the reserpine (RES)-induced progressive parkinsonism model. METHODS: Male rats (6-month-old) received orally the CAR (400 mg/kg) or vehicle and subcutaneously RES (0.01 mg/kg) or vehicle for 28 days (Preventive Phase). From the 29th day, rats received CAR or vehicle daily and RES (0.1 mg/kg) or vehicle every other day (for 23 days, Protective phase). Behavioral tests were conducted throughout the treatment. Upon completion, the animals' brain were processed for tyrosine hydroxylase (TH) immunohistochemical assessment. RESULTS: Our results showed that the chronic treatment of CAR protected against motor disabilities, reducing the time of catalepsy behavior and decreasing the frequency of oral movements, possibly by preserving TH levels in the Ventral Tegmental Area (VTA) and SNpc. CONCLUSION: CAR extract is effective to attenuate motor symptoms in rats associated with increased TH+ levels in the Ventral Tegmental Area (VTA) and SNpc, indicating the potential nutraceutical benefits of CAR extract in a progressive parkinsonism model induced by RES.
Assuntos
Daucus carota , Fármacos Neuroprotetores , Extratos Vegetais , Reserpina , Tirosina 3-Mono-Oxigenase , Animais , Reserpina/toxicidade , Masculino , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Ratos , Daucus carota/química , Tirosina 3-Mono-Oxigenase/metabolismo , Ratos Wistar , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismo , Substância Negra/patologia , Modelos Animais de Doenças , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Corpo Estriado/patologiaRESUMO
OBJECTIVE AND METHODS: We investigated the locomotor, emotional, physiological, and neurobiological effects induced by low-dose reserpine repeated treatment (0.1 mg/kg; 14 injections) in males from the Lewis (LEW), Spontaneously Hypertensive Rats (SHR), and SHR.LEW-(D4Rat76-D4Mgh11) (SLA16) isogenic rat strains, which have different genetic backgrounds on chromosome 4. Behavioral responses in the catalepsy, open-field, and oral movements' tests were coupled with blood pressure, body weight, and striatal tyrosine hydroxylase (TH) level assessments to establish neurobiological comparisons between reserpine-induced impairments and genetic backgrounds RESULTS: Results revealed the SHR strain was more sensitive in the catalepsy test and exhibited higher TH immunoreactivity in the dorsal striatum. The SLA16 strain presented more oral movements, suggesting increased susceptibility to develop oral dyskinesia. CONCLUSIONS: Our results showed the efficacy of repeated treatment with a low dose of reserpine and demonstrated, for the first time, the genetic influence of a specific region of chromosome 4 on the expression of these effects.
Assuntos
Transtornos Parkinsonianos , Reserpina , Masculino , Ratos , Animais , Reserpina/toxicidade , Catalepsia , Comportamento Animal , Ratos Endogâmicos Lew , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/genética , Transtornos Parkinsonianos/metabolismo , Ratos Endogâmicos SHRRESUMO
Epilepsy is a chronic neurological disorder characterized by an abnormal, spontaneous, and synchronized neuronal hyperactivity. Therapeutic approaches for controlling epileptic seizures are associated with pharmacoresistance and side effects burden. Previous studies reported that different natural products may have neuroprotector effects. Sakuranetin (SAK) is a flavanone with antiparasitic, anti-inflammatory, antimutagenic, antiallergic, and antioxidant activity. In the present work, the effect of SAK on seizures in a model of status epilepticus induced by bicuculline (BIC) in mice was evaluated. Male Swiss mice received an intracerebroventricular injection (i.c.v.) of SAK (1, 10, or 20 mg/kg-SAK1, SAK10, or SAK20). Firstly, animals were evaluated in the open field (OF; 20 min), afterwards in the elevated plus maze (EPM) test (5 min). Next, 30 min prior the administration of BIC (1 mg/kg), mice received an injection of SAK (1 or 10 mg/kg, i.c.v.) and were observed in the OF (20 min) for seizures assessment. After behavioral procedures, immunohistochemical analysis of c-Fos was performed. Our main results showed that the lowest doses of SAK (1 and 10 mg/kg) increased the total distance traveled in the OF, moreover protected against seizures and death on the BIC-induced seizures model. Furthermore, SAK treatment reduced neuronal activity on the dentate gyrus of the BIC-treated animals. Taken together, our results suggest an anticonvulsant effect of SAK, which could be used for the development of anticonvulsants based on natural products from herbal source.
Assuntos
Anticonvulsivantes , Produtos Biológicos , Animais , Anticonvulsivantes/farmacologia , Bicuculina/efeitos adversos , Produtos Biológicos/uso terapêutico , Flavonoides , Masculino , Camundongos , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológicoRESUMO
Epilepsy is a chronic neuropathology characterized by an abnormal hyperactivity of neurons that generate recurrent, spontaneous, paradoxical and synchronized nerve impulses, leading or not to seizures. This neurological disorder affects around 70 million individuals worldwide. Pharmacoresistance is observed in about 30% of the patients and long-term use of antiepileptics may induce serious side effects. Thus, there is an interest in the study of the therapeutic potential of bioactive substances isolated from natural products in the treatment of epilepsy. Arthropod venoms contain neurotoxins that have high affinity for molecular structures in the neural tissue such as receptors, transporters and ion channels both in glial and neuronal membranes. This study evaluated the potential neuroprotective effect of melittin (MEL), an active compound of bee venom, in the bicuculline-induced seizure model (BIC) in rats. Male Wistar rats (3 months, 250-300 g) were submitted to surgery for the implantation of a unilateral cannula in the lateral ventricle. After the recovery period, rats received a microinjection of saline solution or MEL (0.1 mg per animal). Firstly, rats were evaluated in the open field (20 min) and in the elevated plus maze (5 min) tests after received microinjection of saline or MEL. After, 30 min later animals received BIC (100 mg/ml) or saline, and their behaviors were analyzed for 20 min in the open field according to a seizure scale. At the end, rats were euthanized, brains collected and processed to glial fibrillary acidic protein (GFAP) immunohistochemistry evaluation. No changes were observed in MEL-treated rats in the open field and elevated plus maze. However, 90% of MEL-treated animals were protected against seizures induced by BIC. There was an increase in the latency for the onset of seizures, accompanied by a reduction of GFAP-immunoreactivity cells in the dentate gyrus and CA1. Thus, our study suggests that MEL has an anticonvulsant potential, and further studies are needed to elucidate the mechanisms involved in this action.
Assuntos
Anticonvulsivantes/uso terapêutico , Astrócitos/efeitos dos fármacos , Venenos de Abelha/uso terapêutico , Hipocampo/efeitos dos fármacos , Meliteno/uso terapêutico , Convulsões/prevenção & controle , Animais , Anticonvulsivantes/farmacologia , Venenos de Abelha/farmacologia , Comportamento Animal/efeitos dos fármacos , Bicuculina , Masculino , Meliteno/farmacologia , Ratos , Ratos Wistar , Convulsões/induzido quimicamenteRESUMO
Current pharmacological approaches to treat Parkinson's disease have low long-term efficacy and important adverse side effects. The development of new pharmacological therapies has focused on novel plant-derived phytochemicals. The alcoholic monoterpene myrtenol has been isolated from several plant species, and has anxiolytic, analgesic, anti-inflammatory and antioxidant actions. Our study evaluated the neuroprotective potential of myrtenol complexed with ß-cyclodextrin (MYR) on a progressive parkinsonism model induced by reserpine (RES) in mice. The complexation with cyclodextrins enhances the pharmacological action of monoterpenes. Male Swiss mice were treated daily with MYR (5 mg/kg, p.o.) and with RES (0.1 mg/kg, s.c.) every other day during 28 days. Behavioural evaluations were conducted across treatment. At the end of the treatment, immunohistochemistry for tyrosine hydroxylase (TH) and oxidative stress parameters were evaluated. Chronic MYR-treatment protected against olfactory sensibility loss, restored short-term memory and decreased RES-induced motor impairments. Moreover, this treatment prevented dopaminergic depletion and reduced the oxidative status index in the dorsal striatum. Therefore, MYR ameliorated motor and non-motor impairments in the progressive animal model of parkinsonism, possibly by an antioxidant action. Additional research is needed to investigate the mechanisms involved in this neuroprotective effect.
Assuntos
ReserpinaRESUMO
The exposure to selective serotonin reuptake inhibitors (SSRIs) during development results in behavioural impairment in adulthood in humans and animal models. Indeed, serotonergic overexpression in early life leads to structural and functional changes in brain circuits that control cognition and emotion. However, the effects of developmental exposure to these substances on the behaviour of adolescent rats are conflicting and remain poorly characterised. We performed a behavioural screening to investigate the effects of postnatal exposure to fluoxetine on memory and behaviours related to anxiety, anhedonia, and depression, as well we evaluate the parvalbumin expression in hippocampus of juvenile (~PND45) female and male rats. Fluoxetine (daily 20 mg/kg s.c. injections from PND7-PND21)- or vehicle-treated adolescent rats went through several behavioural tasks (from PND 38 to PND52) and were subject to transcardial perfusion and brain removal for immunohistochemical analysis (PND53). We found that postnatal exposure to fluoxetine increased anxiety- and depression-like behaviours in the open field and sucrose preference and forced swimming tests, respectively. In addition, this treatment induced working memory and short-term (but not long-term) recognition memory impairments, and reduced parvalbumin-positive interneurons in the hippocampus. In addition, the results revealed developmental sex-dependent effects of fluoxetine postnatal treatment on adolescent rats' behaviour. These outcomes indicate that affective disorders and mnemonic alterations caused by SSRIs perinatal exposure can be present at adolescence.
Assuntos
Cognição/efeitos dos fármacos , Emoções/efeitos dos fármacos , Fluoxetina/farmacologia , Hipocampo/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Parvalbuminas/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Feminino , Hipocampo/metabolismo , Masculino , Memória/efeitos dos fármacos , Neurônios/metabolismo , Ratos , Ratos Wistar , NataçãoRESUMO
A growing body of evidence demonstrates that estrogen and corticosterone (CORT) impact on cognition and emotion. On the one hand, ovarian hormones may have beneficial effects on several neurophysiological processes, including memory. On the other hand, chronic exposure to stressful conditions has negative effects on brain structures related to learning and memory. In the present study, we used the plus-maze discriminative avoidance task (PMDAT) to evaluate the influence of endogenous variations of sex hormones and exposure to different types of prolonged stressors on learning, memory, anxiety-like behavior and locomotion. Female Wistar rats were submitted to seven consecutive days of restraint stress (4â¯h/day), overcrowding (18â¯h/day) or social isolation (18â¯h/day) and tested in different phases of the estrous cycle. The main results showed that: (1) neither stress conditions nor estrous cycle modified PMDAT acquisition; (2) restraint stress and social isolation induced memory impairments; (3) this impairment was observed particularly in females in metestrus/diestrus; (4) stressed females in estrus displayed less risk assessment behavior, suggesting reduced anxiety-like behavior; (5) restraint stress and social isolation, but not overcrowding, elevated corticosterone levels. Taken together, our findings suggest that the phase of the estrous cycle is an important modulatory factor of the cognitive processing disrupted by stress in female rats. Negative effects were observed in metestrus/diestrus, indicating that the peak of sex hormones may protect females against stress-induced memory impairment.
Assuntos
Corticosterona/metabolismo , Estradiol/metabolismo , Ciclo Estral/fisiologia , Transtornos da Memória , Estresse Psicológico , Animais , Modelos Animais de Doenças , Feminino , Transtornos da Memória/etiologia , Transtornos da Memória/metabolismo , Transtornos da Memória/fisiopatologia , Ratos , Ratos Wistar , Estresse Psicológico/complicações , Estresse Psicológico/metabolismo , Estresse Psicológico/fisiopatologiaRESUMO
Alzheimer's disease (AD) is a neurodegenerative disorder that drastically compromises patients' and relatives' quality of life, besides being a significant economic burden to global public health. Its pathophysiology is not completely elucidated yet, hence, the current therapies are restricted to treating the symptoms. Over the years, several epidemiological studies have shown disproportionalities in AD when sex is considered, which has encouraged researchers to investigate the potentiality of sex as a risk factor. Studies in rodent models have been used to investigate mechanistic basis of sex differences in AD, as well as the development of possible new sex-specific therapeutic strategies. However, full knowledge on factors related to this sexual dimorphism remains to be unraveled. Some findings point to differences in genetic and developmental backgrounds either earlier in life or in the aging brain. Herein we summarize the multisystemic framework behind the sex differences in AD and discuss the possible mechanisms involved in these differences raised by the literature so far in an integrative perspective.
Assuntos
Doença de Alzheimer/fisiopatologia , Caracteres Sexuais , Doença de Alzheimer/genética , Doença de Alzheimer/terapia , Animais , Feminino , Humanos , MasculinoRESUMO
Episodic-like memory refers to integration of where and when a certain event (what) happened. The glutamatergic neurotransmission, particularly AMPA and NMDA receptors, in the dorsal hippocampus mediates episodic recall. Ketamine is a non-competitive NMDA antagonist with effect on cognitive performance and plasticity. The goal of this study was to evaluate the acute action of ketamine on behavioural and neurochemical aspects of episodic-like memory (WWWhen/ELM task) through immediate-early gene expression (IEG), c-Fos, in the dorsal hippocampus. Animals received saline 0.9% or ketamine at 8 mg/kg or 15 mg/kg (i.p.) immediately after the second sample. Our data indicate that untreated and saline rats integrate the three elements of episodic-like memory. Conversely, animals treated with ketamine showed impairment of ELM formation. In addition, the highest dose of ketamine increased c-Fos expression in dorsal CA1 subregion when compared to saline rats. Our results indicate that the antagonism of NMDA concurrently impair ELM formation of all three aspects of ELM and increase neuronal activation in dorsal CA1.
Assuntos
Antagonistas de Aminoácidos Excitatórios/efeitos adversos , Ketamina/efeitos adversos , Transtornos da Memória/induzido quimicamente , Memória Episódica , Psicotrópicos/efeitos adversos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Anestésicos Dissociativos/efeitos adversos , Animais , Região CA1 Hipocampal/efeitos dos fármacos , Região CA1 Hipocampal/metabolismo , Região CA1 Hipocampal/patologia , Relação Dose-Resposta a Droga , Masculino , Transtornos da Memória/metabolismo , Transtornos da Memória/patologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos Wistar , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
The high medical importance of Crotalus snakes is unquestionable, as this genus is the second in frequency of ophidian accidents in many countries, including Brazil. With a relative less complex composition compared to other genera venoms, as those from the Bothrops genus, the Crotalus genus venom from South America is composed basically by the neurotoxin crotoxin (a phospholipase A2), the thrombin-like gyroxin (a serinoprotease), a very potent aggregating protein convulxin, and a myotoxic polypeptide named crotamine. Interestingly not all Crotalus snakes express crotamine, which was first described in early 50s due to its ability to immobilize animal hind limbs, contributing therefore to the physical immobilization of preys and representing an important advantage for the envenoming efficacy, and consequently, for the feeding and survival of these snakes in nature. Representing about 10-25% of the dry weight of the crude venom of crotamine-positive rattlesnakes, the polypeptide crotamine is also suggested to be of importance for antivenom therapy, although the contribution of this toxin to the main symptoms of envenoming process remains far unknown until now. Herein, we concomitantly performed in vitro and in vivo assays to show for the first time the dose-dependent response of crotamine-triggered hind limbs paralysis syndrome, up to now believed to be observable only at high (sub-lethal) concentrations of crotamine. In addition, ex vivo assay performed with isolated skeletal muscles allowed us to suggest here that compounds active on voltage-sensitive sodium and/or potassium ion channels could both affect the positive inotropic effect elicited by crotamine in isolated diaphragm, besides also affecting the hind limbs paralysis syndrome imposed by crotamine in vivo. By identifying the potential molecular targets of this toxin, our data may contribute to open new roads for translational studies aiming to improve the snakebite envenoming treatment in human. Interestingly, we also demonstrate that the intraplantal or intraperitoneal (ip) injections of crotamine in mice do not promote pain. Therefore, this work may also suggest the profitable utility of non-toxic analogs of crotamine as a potential tool for targeting voltage-gated ion channels in skeletal muscles, aiming its potential use in the therapy of neuromuscular dysfunctions and envenoming therapy.