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Abstract Objective: To assess whether depression and quality of life scores correlate with glycosylated hemoglobin A (HbA1c) levels in type 2 diabetes mellitus (T2DM) patients of predominant Mayan ethnicity, from a rural community in the state of Yucatán, Mexico. Materials and methods: Instruments: for depression, CES-D (cutoff ≥ 16); for quality of life, D-39; criterion for poor glycemic control, HbA1c ≥ 8%. Results: Depression was detected in 36.3% of 33 diabetic subjects (10 men, 23 women), and their HbA1c levels (mean ± SD) were higher (10.7 ± 2.5%) than for those without depression (8.6 ± 2.2%, p = 0.015; unpaired Student's t-test, two-tailed). Depression occurred in 33.3% of diabetics with HbA1c ≥8%, but only in 3.0% of those with HbA1c < 8% (p = 0.027, Fisher's exact test). HbA1c levels positively correlated with CES-D scores (r2 =0.135; p = 0.035; Pearson). D-39 "Anxiety-Worry" (AW) dimension scores were higher in diabetics with depression (43.3 ± 22.2) than in those without depression (17.7 ± 17.8; p = 0.005, Mann-Whitney U-test). A positive correlation was found between CES-D and AW scores (r2 = 0.304; p = 0.001; Pearson). Conclusions: Considering that depression and anxiety have been related to poor self-care for achieving a good glycemic control, we propose the concomitant use of CES-D and D-39, which are validated and easy-to-apply instruments, as screening tests to detect depression and anxiety in T2DM patients residing in rural communities. Therefore, if patients test positive on one or both instruments, they can be referred to a psychiatrist to confirm the diagnosis and provide appropriate therapy. This would help to promote adherence to diabetes control measures and improve their quality of life.
Resumen Objetivo: Evaluar si las puntuaciones de depresión y calidad de vida se correlacionan con los niveles de hemoglobina glucosilada (HbA1c) en pacientes con diabetes mellitus tipo 2 (DM2) de etnia maya predominante, de una comunidad rural en el estado de Yucatán, México. Materiales y Métodos: Instrumentos: para depresión, CES-D (punto de corte ≥ 16); para calidad de vida, D-39; criterio de mal control glucémico, HbA1c ≥ 8%. Resultados: Se detectó depresión en el 36.3% de 33 sujetos diabéticos (10 hombres, 23 mujeres), y sus niveles de HbA1c (media ± DE) fueron más altos (10.7 ± 2.5%) que para los que no tenían depresión (8.6 ± 2.2%, p = 0.015; prueba t de Student, no pareada). La depresión se presentó en el 33.3% de los diabéticos con HbA1c ≥ 8%, pero solo en el 3.0% de aquellos con HbA1c <8% (p = 0.027, prueba exacta de Fisher). Los niveles de HbA1c se correlacionaron positivamente con las puntuaciones CES-D (r2 = 0.135; p = 0.035; Pearson). Los puntajes de la dimensión "Ansiedad-Preocupación" (AW) del D-39 fueron más altos en diabéticos con depresión (43.3 ± 22.2) que en aquellos sin depresión (17.7 ± 17.8; p = 0.005, prueba U de Mann-Whitney). Se encontró una correlación positiva entre las puntuaciones CES-D y AW (r2 = 0.304; p = 0.001; Pearson). Conclusiones: Considerando que la depresión y la ansiedad han sido asociadas a autocuidados inadecuados para alcanzar un buen control glicémico, proponemos el uso concomitante de CES-D y D-39, que son instrumentos validados y de fácil aplicación, como pruebas de cribado para detectar depresión y ansiedad en pacientes con DM2 residentes en comunidades rurales. Por lo tanto, si los pacientes dan positivo en uno o ambos instrumentos, se les puede derivar a un psiquiatra para confirmar el diagnóstico y proporcionar la terapia adecuada. Esto ayudaría a promover el cumplimiento de las medidas de control de la diabetes y a mejorar su calidad de vida.
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Gut dysbiosis is considered a risk factor for Parkinson's disease (PD), and chronic treatment with probiotics could prevent it. Here we report the assessment of a probiotic mixture [Lacticaseibacillus rhamnosus GG (LGG), and Bifidobacterium animalis lactis BB-12 (BB-12)] administered to male rats 2 weeks before and 3 weeks after injecting 6-hydroxydopamine (6-OHDA) into the right striatum, a model that mimics the early stages of PD. Before and after lesion, animals were subjected to behavioral tests: narrow beam, cylinder test, and apomorphine (APO)-induced rotations. Dopaminergic (DA) denervation and microglia recruitment were assessed with tyrosine hydroxylase (TH+) and ionized calcium-binding protein-1 adapter (Iba1+) immunostaining, respectively. Post 6-OHDA injury, rats treated with sunflower oil (probiotics vehicle) developed significant decrease in crossing speed and increases in contralateral paw slips (narrow beam), forepaw use asymmetry (cylinder), and APO-induced rotations. In striatum, 6-OHDA eliminated ≈2/3 of TH+ area and caused significant increase of Iba1+ microglia population. Retrograde axonal degeneration suppressed ≈2/5 of TH+ neurons in the substantia nigra pars compacta (SNpc). In hemiparkinsonian rats, probiotics treatment significantly improved the crossing speed, and also reduced paw slips (postlesion days 14 and 21), the loss of TH+ neurons in SNpc, and the loss of TH+ area and of Iba1+ microglia count in striatum, without affecting the proportion of microglia morphological phenotypes. Probiotics treatment did not attenuate forepaw use asymmetry nor APO-induced rotations. These results indicate that the mixture of probiotics LGG and BB-12 protects nigrostriatal DA neurons against 6-OHDA-induced damage, supporting their potential as preventive treatment of PD.
Assuntos
Bifidobacterium animalis , Lacticaseibacillus rhamnosus , Transtornos Motores , Doença de Parkinson , Probióticos , Ratos , Masculino , Animais , Oxidopamina , Bifidobacterium animalis/metabolismo , Doença de Parkinson/patologia , Microglia/metabolismo , Lacticaseibacillus , Substância Negra/metabolismo , Transtornos Motores/patologia , Corpo Estriado/metabolismo , Neurônios Dopaminérgicos/metabolismo , Dopamina , Apomorfina/farmacologia , Tirosina 3-Mono-Oxigenase/metabolismo , Probióticos/farmacologiaRESUMO
Blueberries (BB) are rich in antioxidant polyphenols, and their intake could prevent Parkinson's disease (PD). Here we assessed whether rats chronically fed dried raw BB develop resistance to dopaminergic denervation and motor disorders caused by unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA), a dopaminergic neurotoxin acting mainly by inducing oxidative stress. Male rats were fed either with LabDiet® alone or supplemented with 3% lyophilized raw BB for 2 weeks before and 3 weeks after injecting 6-OHDA (day 0) or vehicle (mock lesion) into the right striatum. The cylinder test was performed on days -14, -7, -1, +7, +14, and +21; the percentage of ipsilateral forepaw (IF) use asymmetry was determined by counting the wall contacts made with either forepaw or with both. Apomorphine (0.25 mg/kg, s.c.)-induced rotation was performed on days -1, +7, +14, and +21. Full contralateral rotations were counted in 3-min periods, every 15 min, up to 90 min. Striatal slices were immunostained for tyrosine hydroxylase (TH) and the ionized calcium-binding protein-1 adapter (Iba1) [immunoreactive area or microglia count in right striatum expressed as % of the left striatum]. Antioxidants in BB methanolic extracts neutralized the free radical 2,2-diphenyl-1-picrylhydrazyl in a concentration-dependent manner. Anthocyanins have been reported as the most abundant polyphenols in BB. Using the pH differential method, the total anthocyanin content (malvidin-3-glucoside equivalents) in raw BB averaged 21.04 mg/g dry weight. The range of anthocyanin intake by rats throughout the study varied from 37.7 to 72.2 mg/kg body weight. The time and food type factors, as well as their interaction were significant according to two-way RM-ANOVA in both the apomorphine-induced rotations and the cylinder test. Compared with LabDiet® alone, chronic supplementation with 3% dried raw BB decreased apomorphine-induced rotations on days +14 and +21 (p < 0.001) and produced a 46% reduction in total rotations post-surgery (p < 0.05), but only caused a partial, non-significant, decrease of IF asymmetry. BB supplementation reduced TH loss in the striatum (p < 0.05) but did not attenuate the increase of Iba1+ microglia. The consumption of 3% dried raw blueberries attenuates dopaminergic denervation and partially reverses motor disorders in the 6-OHDA-induced PD model in rats. The phytochemicals of raw blueberries that contribute to the observed neuroprotective effect are yet to be identified.
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Apomorfina , Mirtilos Azuis (Planta) , Animais , Apomorfina/farmacologia , Corpo Estriado , Masculino , Oxidopamina , Ratos , Substância NegraRESUMO
In this study, 24 breast milk samples, obtained from rural Maya women, from municipalities of Yucatan, Mexico, were analyzed for organochlorine pesticide (OCP) residues by gas chromatography. Recent studies have shown that Maya communities have a poor perception about the proper usage and handling of OCP. The karstic soil in this area has a high vulnerability to groundwater pollution by the use of OCP in agriculture and livestock activities. The impact of the ecosystem on human health is much more critical due to the prevailing poverty and a very low educational level of these communities. About 30% of the Maya population consumes water directly from contaminated wells and sinkholes, resulting in a chronic exposure to OCP. The samples served to identify and quantify high levels of OCP residues (18.43 mg/kg of heptachlor epoxide and 1.92 mg/kg of endrin in the metropolitan zone; 2.10 mg/kg of dieldrin, 0.117 mg/kg of endosulfan II, 0.103 mg/kg of heptachlor, 0.178 mg/kg of endrin, and 0.127 mg/kg of endrin aldehyde in the main agricultural zone and on the west coast). The detected levels of OCP residues are a major concern and represent a potential risk to women and children in the region. This could be associated with the high rates of cervical uterine and breast cancer mortality in Yucatan. Thus, regulations on the usage of OCP and their enforcement are necessary, and it is important to establish a yearly monitoring program for OCP residues in breast milk and groundwater, as well as to implement health promotion programs for women in particular and the general population in general.
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Poluentes Ambientais/metabolismo , Exposição Materna/estatística & dados numéricos , Leite Humano/metabolismo , Agricultura , Criança , Cromatografia Gasosa , Dieldrin/análise , Dieldrin/metabolismo , Endossulfano/análise , Endossulfano/metabolismo , Monitoramento Ambiental , Poluentes Ambientais/análise , Feminino , Água Subterrânea/química , Heptacloro/análise , Humanos , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/metabolismo , México/etnologia , Leite Humano/química , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/metabolismo , Praguicidas/análise , Praguicidas/metabolismo , Grupos Populacionais , SoloRESUMO
Extrapyramidal syndromes (EPS) caused by antipsychotic therapy are currently treated with anticholinergics that lack selectivity for the five muscarinic receptor subtypes. Since these receptors are heterogeneously expressed among the different classes of striatal neurons and their afferents, it can be expected that their simultaneous blockade will cause distinct, sometimes opposed, effects within the striatal circuitry. In order to test the hypothesis that the differential blockade of the muscarinic receptor subtypes would influence their potency and efficacy to prevent EPS, here we tested four anticholinergics with varying order of affinities for the muscarinic receptor subtypes, and compared their dose-response curves to inhibit haloperidol-induced catalepsy in male rats. Drugs were applied into the lateral ventricle 15 min before haloperidol (2 mg/kg, s.c.). Catalepsy was measured in the bar test at 15 min intervals during 5 h. The preferential M1/M4 antagonist pirenzepine (3, 10, 30, 100, and 300 nmol) caused a dose-dependent inhibition of catalepsy intensity: ED50 = 5.6 nmol [95% CI, 3.9-8.1], and latency: ED50 = 5.6 nmol [95% CI, 3.7-8.6]. Pirenzepine had the steepest dose-response curve, producing maximal inhibition (84 ± 5%) at the dose of 10 nmol, while its effect tended to reverse at higher doses (62 ± 11%). The purported M1/M3 antagonist 4-DAMP (30, 100, and 300 nmol) also caused a dose-dependent inhibition of catalepsy intensity: ED50 = 29.5 nmol [95% CI, 7.0 to 123.0], and latency: ED50 = 28.5 nmol [95% CI, 2.2 to 362.0]. However, the curve for 4-DAMP had a less pronounced slope, reaching its maximal effect (63 ± 14%) at the dose of 300 nmol. The M2/M4 antagonist AF-DX 116 (10, 30, and 300 nmol) only caused a partial inhibition of catalepsy (30 ± 11%) at the dose of 30 nmol, but this changed to a non-significant increment (15 ± 10%) at the dose of 100 nmol. The alleged M4 antagonist tropicamide (30, 100, 300, and 600 nmol) produced a partial inhibition of catalepsy (36 ± 12%) at the dose of 300 nmol, but lacked effect at higher or lower doses. Concurrent treatment with pirenzepine (10 nmol) and tropicamide (300 nmol) produced an effect similar to that of tropicamide alone. The greater potency and efficacy of pirenzepine for catalepsy inhibition could be due to its higher affinity for M1 receptors and, to a lesser extent, for M4 receptors. It is suggested that selective M1 antagonists would be more effective than M2, M3 or M4 antagonists to prevent EPS caused by antipsychotic drugs.
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Antipsicóticos/toxicidade , Catalepsia/induzido quimicamente , Catalepsia/tratamento farmacológico , Antagonistas Colinérgicos/farmacologia , Haloperidol/toxicidade , Receptores Muscarínicos/metabolismo , Análise de Variância , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Interações Medicamentosas , Masculino , Pirenzepina/uso terapêutico , Ligação Proteica/efeitos dos fármacos , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Fatores de TempoRESUMO
In order to assess whether caffeine and theophylline have the same potency and efficacy to reverse the impairment of motor function caused by acute or chronic interruption of striatal dopamine transmission, a comparison of their dose-response relationship was made in the acute model of haloperidol-induced catalepsy, and the chronic model of unilateral lesion of the dopamine nigrostriatal pathway with 6-hydroxydopamine. At equimolar doses, both drugs reduced catalepsy intensity and increased its onset latency in a dose-dependent fashion, showing comparable potencies and attaining the maximal effect at similar doses. Catalepsy intensity: caffeine ED50 = 24.1 µmol/kg [95% CI, 18.4-31.5]; theophylline ED50 = 22.0 µmol/kg [95% CI, 17.0-28.4]. Catalepsy latency: caffeine ED50 = 27.0 µmol/kg [95% CI, 21.1-34.6]; theophylline ED50 = 28.8 µmol/kg [95% CI, 22.5-36.7]. In one group of hemiparkinsonian rats (n = 5), caffeine caused a dose-dependent recovery of the contralateral forepaw stepping: ED50 = 2.4 µmol/kg/day [95% CI, 1.9-3.1]), reaching its maximum at the dose of 5.15 µmol/kg/day. When the treatment of these same rats was switched to 5.15 µmol/kg/day of theophylline, the stepping recovery was only 51 ± 12% of that induced by caffeine. Assessing the dose-response relationship of theophylline in another group of hemiparkinsonian rats (n = 7) revealed that it caused stepping recovery in an all-or-none fashion. Thus, the three lower doses had no effect, but at the dose of 5.15 µmol/kg/day theophylline suddenly increased the stepping to 56 ± 5% of the maximal effect observed when the treatment of these same rats was switched to an equimolar dose of caffeine. Increasing the dose of theophylline up to 15.45 µmol/kg/day caused no further stepping improvement since it was only 41 ± 6% of the maximal effect produced by caffeine at the dose of 5.15 µmol/kg/day. Given that theophylline showed less potency and efficacy than caffeine to reverse the motor impairment caused by chronic, but not acute, interruption of striatal dopaminergic transmission in rats, it is suggested that caffeine would provide more benefits than theophylline to improve the motor function in patients with Parkinson's disease.
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Cafeína/farmacologia , Corpo Estriado/efeitos dos fármacos , Neurônios Dopaminérgicos/efeitos dos fármacos , Destreza Motora/efeitos dos fármacos , Teofilina/farmacologia , Animais , Catalepsia/induzido quimicamente , Relação Dose-Resposta a Droga , Haloperidol/efeitos adversos , Haloperidol/antagonistas & inibidores , Masculino , Oxidopamina/efeitos adversos , Oxidopamina/antagonistas & inibidores , Transtornos Parkinsonianos/induzido quimicamente , RatosRESUMO
We describe the design and evaluation of an electronic system for the automatic recording of motor activity in rats. The device continually locates the position of a rat inside a transparent acrylic cube (50 cm/side) with infrared sensors arranged on its walls so as to correspond to the x-, y-, and z-axes. The system is governed by two microcontrollers. The raw data are saved in a text file within a secure digital memory card, and offline analyses are performed with a library of programs that automatically compute several parameters based on the sequence of coordinates and the time of occurrence of each movement. Four analyses can be made at specified time intervals: traveled distance (cm), movement speed (cm/s), time spent in vertical exploration (s), and thigmotaxis (%). In addition, three analyses are made for the total duration of the experiment: time spent at each x-y coordinate pair (min), time spent on vertical exploration at each x-y coordinate pair (s), and frequency distribution of vertical exploration episodes of distinct durations. User profiles of frequently analyzed parameters may be created and saved for future experimental analyses, thus obtaining a full set of analyses for a group of rats in a short time. The performance of the developed system was assessed by recording the spontaneous motor activity of six rats, while their behaviors were simultaneously videotaped for manual analysis by two trained observers. A high and significant correlation was found between the values measured by the electronic system and by the observers.
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Atividade Motora , Neurociências/instrumentação , Software , Animais , Apresentação de Dados , Desenho de Equipamento , Abrigo para Animais , Raios Infravermelhos , Masculino , Ratos , Ratos Wistar , Design de Software , Gravação de VideoteipeRESUMO
Anatomical and functional studies have shown that the NADPH-diaphorase-positive cholinergic neurons of the pedunculopontine nucleus (PPN) send projections to several areas in the brain. The purpose of this work was to investigate whether bilateral lesions with quinolinic acid, a neurotoxin with greater selectivity for NADPH-diaphorase-positive neurons, aimed at the compact portion of the PPN would affect the performance of adaptive behaviors, such as sleep, locomotion, and spontaneous alternation. Lesioned animals were divided in a low lesion group (LL, <50% neuron loss) and a high lesion group (HL, ≥50% neuron loss). The LL animals did not show any significant changes in sleep patterns, as compared to controls. In contrast, the HL group showed a significant increase in the number of REM sleep periods, and a reduction of REM sleep average duration, but did not differ in the total time spent in REM sleep. HL animals also showed an increase in the number of SWS periods, though wakefulness parameters did not show significant alterations. The duration and number of both REM and SWS sleep episodes were significantly correlated with the number of NADPH-diaphorase-positive neurons in the PPN. The short-term habituation pattern of locomotion, the vertical exploratory activity, as well as the thigmotaxis (an index of emotionality), displayed by LL and HL rats in a novel environment were similar to those of control animals. Likewise, there were no significant differences in spontaneous alternation among the groups. Our results indicate that quinolinic acid lesions of NADPH-diaphorase-positive cholinergic neurons localized in the posterior region of the PPN disrupt normal sleep structure, while motor activity and spontaneous alternation remain unaffected.
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Emoções/fisiologia , Comportamento Exploratório/fisiologia , Locomoção/fisiologia , Memória de Curto Prazo/fisiologia , Núcleo Tegmental Pedunculopontino/fisiologia , Ácido Quinolínico/toxicidade , Fases do Sono/fisiologia , Animais , Neurônios Colinérgicos/metabolismo , Neurônios Colinérgicos/fisiologia , Emoções/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Masculino , Memória de Curto Prazo/efeitos dos fármacos , NADPH Desidrogenase/metabolismo , Núcleo Tegmental Pedunculopontino/efeitos dos fármacos , Ratos , Ratos Wistar , Fases do Sono/efeitos dos fármacosRESUMO
Chronic caffeine consumption has been inversely associated with the risk of developing Parkinson's disease. Here we assessed whether chronic caffeine treatment increases the resistance of male Wistar rats to haloperidol (1mg/kg, s.c.)-induced catalepsy, measured in the bar test at 15 min intervals during 3h. Caffeine (5mg/kg/day) was delivered for 6 months via drinking water. Control rats received only tap water. Treatments began when animals were 3-4 months old. In order to unveil long-lasting catalepsy refractoriness not attributable to the presence of caffeine in the brains of rats, they were evaluated from day 18 to day 27 after caffeine withdrawal, a time that is far in excess for the full excretion of a caffeine dose in this species. The average cataleptic immobility measured in caffeine-treated rats (n=23) was 1148+/-140 s, a value 34+/-8% lower than that recorded in control animals (n=20), whose mean immobility was 1736+/-137 s (P=0.0026, t-test). The percentage of catalepsy reduction measured in caffeine-treated rats evaluated on days 18-20 after caffeine discontinuation (-32+/-13%, n=12, P<0.05) was comparable to the catalepsy decrease recorded in those animals tested on days 21-27 (-36+/-10%, n=11, P<0.02), a finding compatible with the notion that the effect was indeed mediated by enduring changes of brain functioning and not by the physical presence of caffeine or its metabolites. Caffeine-treated rats also had higher catalepsy latency scores compared with control rats (P<0.01, U-test). The present findings show that chronic consumption of caffeine produces perdurable resistance to catalepsy induced by dopamine receptor blockade, possibly through enhancement of dopamine transmission, giving further support to the epidemiological results indicating that prolonged caffeine consumption affords neuroprotection against Parkinson's disease.
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Cafeína/farmacologia , Catalepsia/prevenção & controle , Estimulantes do Sistema Nervoso Central/farmacologia , Haloperidol , Fármacos Neuroprotetores/farmacologia , Animais , Cafeína/administração & dosagem , Cafeína/uso terapêutico , Catalepsia/induzido quimicamente , Catalepsia/fisiopatologia , Estimulantes do Sistema Nervoso Central/uso terapêutico , Suscetibilidade a Doenças , Antagonistas dos Receptores de Dopamina D2 , Masculino , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/uso terapêutico , Ratos , Ratos Wistar , Fatores de TempoRESUMO
This article describes the design and preliminary evaluation of a small-sized and low energy consumption wearable wireless telemetry system for the recording of extracellular neuronal activity, with the possibility of selecting one of four channels. The system comprises four radio frequency (RF) transceivers, three microcontrollers, and a digital amplifier and filter. This constitutes an innovative distributed processing approach. Gain, cutoff frequencies, and channel selection are remotely adjusted. Digital data transmission is used for both the bioelectrical signals and the control commands. This feature offers superior immunity to external RF interference. Real-time viewing of the acquired data allows the researcher to select only relevant data for storage. Simultaneous recordings of neuronal activity from the striatum of a freely moving rat, both with the wireless device and with a wired data acquisition system, are shown.
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Potenciais de Ação/fisiologia , Eletrofisiologia/instrumentação , Telemetria/instrumentação , Animais , Eletrodos Implantados , Espaço Extracelular/fisiologia , Masculino , Microeletrodos , Ratos , Ratos Wistar , SoftwareRESUMO
The effects of chronic oral treatment with low doses of caffeine (1-3 mg/kg) and trihexyphenidyl (0.1-0.2 mg/kg) were tested on hemiparkinsonian rats, which received the following treatments in a counterbalanced order: vehicle, caffeine, trihexyphenidyl, and caffeine plus trihexyphenidyl. Three preclinical models were used: the stepping test, the cylinder test, and the staircase test. Compared to pre-lesion values, the forepaw contralateral to the dopamine-denervated side showed impaired stepping, fewer wall contacts in the cylinder test, and fewer pellets retrieved in the staircase test. In the stepping test both doses of caffeine produced a complete recovery of motor function (100%), whereas the effect of trihexyphenidyl was less intense (77-80%). In this same test the maximal effect of drugs did not develop tolerance during 2-3 weeks, and was completely reversible after drug cessation. In the cylinder test only the wall contacts performed simultaneously with both forepaws were significantly increased by caffeine (3 mg/kg) and trihexyphenidyl (0.2 mg/kg), and this effect was also reversible. In the staircase test none of the treatments improved food pellet retrieval with the contralateral forepaw. Altogether, these results show that chronic treatment with caffeine, at doses similar to daily human consumption, produces a sustained improvement in the use of the contralateral forelimb in unilaterally 6-hydroxydopamine denervated rats, without the development of tolerance. Although the combined administration of caffeine plus trihexyphenidyl showed no synergism in these models, the results suggest that low doses of caffeine (1-3 mg/kg/day) could be of therapeutic value for the reversal of motor symptoms in parkinsonian patients.
Assuntos
Antiparkinsonianos/uso terapêutico , Cafeína/uso terapêutico , Estimulantes do Sistema Nervoso Central/uso terapêutico , Doença de Parkinson Secundária/tratamento farmacológico , Doença de Parkinson Secundária/fisiopatologia , Triexifenidil/uso terapêutico , Animais , Antiparkinsonianos/administração & dosagem , Encéfalo/patologia , Cafeína/administração & dosagem , Estimulantes do Sistema Nervoso Central/administração & dosagem , Relação Dose-Resposta a Droga , Comportamento Exploratório/fisiologia , Membro Anterior/fisiologia , Lateralidade Funcional/fisiologia , Força da Mão/fisiologia , Hidroxidopaminas , Imuno-Histoquímica , Locomoção/fisiologia , Masculino , Doença de Parkinson Secundária/induzido quimicamente , Equilíbrio Postural/fisiologia , Ratos , Ratos Wistar , Percepção Espacial/fisiologia , Técnicas Estereotáxicas , Triexifenidil/administração & dosagemRESUMO
The possible synergism between caffeine and muscarinic antagonists to inhibit haloperidol-induced catalepsy was investigated with the bar test in rats. Pretreatment with low doses of caffeine (1-3 mg/kg), a non-selective adenosine antagonist, dose dependently reduced the intensity and increased the onset latency of catalepsy induced by haloperidol (0.5-2 mg/kg). Similar effects were produced by the muscarinic antagonists atropine (4.1 mg/kg), and trihexyphenidyl (THP, 0.01-3 mg/kg). THP inhibited catalepsy intensity with an ED(50) of 0.38 mg/kg, and increased its onset latency with an ED(50) of 0.52 mg/kg. The anticataleptic effect of anticholinergics was potentiated when a low dose of caffeine (1 mg/kg) was applied simultaneously. In the presence of caffeine, THP inhibited catalepsy intensity with an ED(50) of 0.19 mg/kg, and prolonged the latency with an ED(50) of 0.30 mg/kg. The synergism was more evident when THP was administered at subthreshold doses that were unable to modify haloperidol-induced catalepsy when applied alone, but produced a clear inhibition of catalepsy when injected with caffeine. To assess whether repeated administration of caffeine could induce tolerance to the synergism with THP, a group of rats was pretreated with three daily doses of caffeine (1 mg/kg) for seven days, and the catalepsy test was performed on the eighth day. In these animals, caffeine was still able to enhance the anticataleptic actions of THP, suggesting that repeated administration of 1 mg/kg caffeine does not induce tolerance to the synergism with anticholinergics. These results indicate that low doses of caffeine enhance the anticataleptic actions of muscarinic antagonists, and leave open the possibility of using caffeine as adjunctive therapy to reduce the doses and the adverse effects of anticholinergics in Parkinson's disease.