RESUMEN
Anxiety is a mental disorder with a growing worldwide incidence due to the SARS-CoV-2 virus pandemic. Pharmacological therapy includes drugs such as benzodiazepines (BDZs) or azapirones like buspirone (BUSP) or analogs, which unfortunately produce severe adverse effects or no immediate response, respectively. Medicinal plants or their bioactive metabolites are a shared global alternative to treat anxiety. Palmitone is one active compound isolated from Annona species due to its tranquilizing activity. However, its influence on neural activity and possible mechanism of action are unknown. In this study, an electroencephalographic (EEG) spectral power analysis was used to corroborate its depressant activity in comparison with the anxiolytic-like effects of reference drugs such as diazepam (DZP, 1 mg/kg) and BUSP (4 mg/kg) or 8-OH-DPAT (1 mg/kg), alone or in the presence of the GABAA (picrotoxin, PTX, 1 mg/kg) or serotonin 5-HT1A receptor antagonists (WAY100634, WAY, 1 mg/kg). The anxiolytic-like activity was assayed using the behavioral response of mice employing open-field, hole-board, and plus-maze tests. EEG activity was registered in both the frontal and parietal cortex, performing a 10 min baseline and 30 min recording after the treatments. As a result, anxiety-like behavior was significantly decreased in mice administered with palmitone, DZP, BUSP, or 8-OH-DPAT. The effect of palmitone was equivalent to that produced by 5-HT1A receptor agonists but 50% less effective than DZP. The presence of PTX and WAY prevented the anxiolytic-like response of DZP and 8-OH-DPAT, respectively. Whereas only the antagonist of the 5-HT1A receptor (WAY) inhibited the palmitone effects. Palmitone and BUSP exhibited similar changes in the relative power bands after the spectral power analysis. This response was different to the changes induced by DZP. In conclusion, brain electrical activity was associated with the anxiolytic-like effects of palmitone implying a serotoninergic rather than a GABAergic mechanism of action.
Asunto(s)
Ansiolíticos , COVID-19 , Ratones , Animales , Ansiolíticos/farmacología , Ansiolíticos/uso terapéutico , Buspirona/farmacología , Diazepam/farmacología , Receptor de Serotonina 5-HT1A , 8-Hidroxi-2-(di-n-propilamino)tetralin/farmacología , SARS-CoV-2 , Agonistas de Receptores de Serotonina/farmacología , ElectroencefalografíaRESUMEN
Responding appropriately to stress is essential for survival, yet in pathological states, these responses can develop into debilitating conditions such as post-traumatic stress disorder and generalized anxiety. While genetic models have provided insight into the neurochemical and neuroanatomical pathways that underlie stress, little is known about how evolutionary processes and naturally occurring variation contribute to the diverse responses to stressful stimuli observed in the animal kingdom. The Mexican cavefish is a powerful system to address how altered genetic and neuronal systems can give rise to altered behaviors. When introduced into a novel tank, surface fish and cavefish display a stereotypic stress response, characterized by reduced exploratory behavior and increased immobility, akin to "freezing". The stress response in cave and surface forms is reduced by pharmacological treatment with the anxiolytic drug, buspirone, fortifying the notion that behavior in the assay represents a conserved stress state. We find that cave populations display reduced behavioral measures of stress compared to surface conspecifics, including increased time in the top half of the tank and fewer periods of immobility. Further, reduced stress responses are observed in multiple independently derived cavefish populations, suggesting convergence on loss of behavioral stress responses in the novel tank assay. These findings provide evidence of a naturally occurring species with two drastically different forms in which a shift in predator-rich ecology to one with few predators corresponds to a reduction in stress behavior.
Asunto(s)
Ansiolíticos/farmacología , Conducta Animal/efectos de los fármacos , Buspirona/farmacología , Characiformes , Estrés Psicológico/fisiopatología , AnimalesRESUMEN
Fetal Alcohol Spectrum Disorders (FASD) is a syndrome characterized by neurological and behavioral impairments. A recently discovered hallmark of FASD is impaired social behavior. Avoidance of social interaction typical of FASD may be the result of increased anxiety. Previously, the zebrafish was successfully used to model embryonic alcohol induced social abnormalities. Here, we analyzed both anxiety and social responses using a zebrafish FASD model, in adult fish. We exposed zebrafish embryos to low concentrations of ethanol (0.1%; 0.25%; 0.5% and 1% v/v) for 2h at, 24h post-fertilization, to mimic the most prevalent milder FASD cases, and investigated the ensuing alterations in adult, 4-month-old, zebrafish. We studied social interaction in the social preference task and anxiety in the novel tank task. We observed an ethanol dose dependent reduction of time spend in the conspecific zone compared to control, corroborating prior findings. We also found significant changes in the novel tank (e.g. increased bottom dwell time, increased distance to top) suggesting elevated anxiety to control, but we also found, using an anxiolytic drug buspirone, that reduction of anxiety is associated with reduced shoaling. Our results confirm that embryonic alcohol exposure disrupts social behavior, and also show that its effects on anxiety related phenotypes may be genotype, alcohol administration method, experimental procedure and test-context dependent.
Asunto(s)
Ansiedad/etiología , Trastornos del Espectro Alcohólico Fetal/psicología , Conducta Social , Animales , Ansiolíticos/farmacología , Ansiedad/tratamiento farmacológico , Reacción de Prevención/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Buspirona/farmacología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Embrión no Mamífero/efectos de los fármacos , Etanol/toxicidad , Femenino , Masculino , Distribución Aleatoria , Pez CebraRESUMEN
The assessment of shoaling in adult zebrafish is technically difficult, but important, given their social nature. The present study aimed to characterize a new protocol using simple automated tracking software to evaluate general behavior and social interaction simultaneously. To this end, we used a single tank with a central transparent glass division and placed one zebrafish on each side for 5 min. This strategy allows fish to interact visually at the same time that individual automated evaluation of behavior can be easily performed. Our results showed that, when two fish are placed side-by-side, there is an increase in their height in the tank compared with isolated fish and they remain close to each other. The pharmacological treatments with benzodiazepines (bromazepam and clonazepam) and the serotonergic drugs buspirone, fluoxetine, and escitalopram did not affect locomotion at the concentrations tested, except for the highest concentration of buspirone. Nevertheless, benzodiazepines increased interfish distance (i.e. reduced shoaling behavior) and serotonergic drugs elevated height in the tank. These results support the use of the side-by-side exploratory test for behavioral studies with the zebrafish, including high-throughput behavioral screening for antidepressants and anxiolytics.
Asunto(s)
Conducta Exploratoria , Reconocimiento de Normas Patrones Automatizadas/métodos , Pruebas Psicológicas , Conducta Social , Programas Informáticos , Pez Cebra , Animales , Bromazepam/farmacología , Buspirona/farmacología , Citalopram/farmacología , Clonazepam/farmacología , Relación Dosis-Respuesta a Droga , Conducta Exploratoria/efectos de los fármacos , Miedo , Femenino , Fluoxetina/farmacología , Masculino , Psicotrópicos/farmacología , Estrés Psicológico , Visión Ocular , Pez Cebra/fisiologíaRESUMEN
Serotonin (5-HT) has been proposed as a possible encoder of reward. Nevertheless, the role of this neurotransmitter in reward-based tasks is not well understood. Given that the major serotonergic circuit in the rat brain comprises the dorsal raphe nuclei and the medial prefrontal cortex (mPFC), and because the latter structure is involved in the control of complex behaviors and expresses 1A (5-HT1A), 2A (5-HT2A), and 3 (5-HT3) receptors, the aim was to study the role of 5-HT and of these receptors in the acquisition and extinction of a reward-dependent operant conditioning task. Long Evans rats were trained in an operant conditioning task while receiving fluoxetine (serotonin reuptake inhibitor, 10mg/kg), tianeptine (serotonin reuptake enhancer, 10mg/kg), buspirone (5-HT1A partial agonist, 10mg/kg), risperidone (5-HT2A antagonist, 1mg/kg), ondansetron (5-HT3 antagonist, 2mg/kg) or vehicle. Then, animals that acquired the operant conditioning without any treatment were trained to extinct the task in the presence of the pharmacological agents. Fluoxetine impaired acquisition but improved extinction. Tianeptine administration induced the opposite effects. Buspirone induced a mild deficit in acquisition and had no effects during the extinction phase. Risperidone administration resulted in learning deficits during the acquisition phase, although it promoted improved extinction. Ondansetron treatment showed a deleterious effect in the acquisition phase and an overall improvement in the extinction phase. These data showed a differential role of 5-HT in the acquisition and extinction of an operant conditioning task, suggesting that it may have a dual function in reward encoding.
Asunto(s)
Receptor de Serotonina 5-HT1A/metabolismo , Receptor de Serotonina 5-HT2A/metabolismo , Receptores de Serotonina 5-HT3/metabolismo , Recompensa , Serotonina/metabolismo , Animales , Buspirona/farmacología , Fluoxetina/farmacología , Ratas Long-Evans , Agonistas del Receptor de Serotonina 5-HT1/farmacología , Inhibidores Selectivos de la Recaptación de Serotonina/farmacologíaRESUMEN
A major hindrance for the development of psychiatric drugs is the prediction of how treatments can alter complex behaviors in assays which have good throughput and physiological complexity. Here we report the development of a medium-throughput screen for drugs which alter anxiety-like behavior in adult zebrafish. The observed phenotypes were clustered according to shared behavioral effects. This barcoding procedure revealed conserved functions of anxiolytic, anxiogenic and psychomotor stimulating drugs and predicted effects of poorly characterized compounds on anxiety. Moreover, anxiolytic drugs all decreased, while anxiogenic drugs increased, serotonin turnover. These results underscore the power of behavioral profiling in adult zebrafish as an approach which combines throughput and physiological complexity in the pharmacological dissection of complex behaviors.
Asunto(s)
Ansiolíticos/farmacología , Ansiedad/tratamiento farmacológico , Animales , Buspirona/farmacología , Cafeína/farmacología , Diazepam/farmacología , Evaluación Preclínica de Medicamentos , Reacción Cataléptica de Congelación/efectos de los fármacos , Serotonina/metabolismo , Natación , Pez CebraRESUMEN
A buspirona é o primeiro fármaco da classe das azapironas e a única comercializada no Brasil. O objetivo do presente trabalho foi conduzir uma revisão de literatura sobre os aspectos farmacológicos da buspirona, bem como demonstrar seus efeitos anticonvulsivantes e neuroprotetores no modelo de convulsão induzido por pilocarpina. Para tanto, foi realizada uma revisão da literatura usando as palavras-chaves buspirone, action mechanism, pharmacokinetics, indications, adverse effects, nomenclature e structure, por intermédio do MEDLINE e LILACS, bem como foram inseridos os resultados experimentais encontrados em camundongos pré-tratados com buspirona no modelo de convulsão induzido por pilocarpina. A busca incluiu todos os artigos completos, resumos, estudos de caso, pré-clínicos e clínicos nos idiomas português e inglês compreendidos entre os anos de 1982 e 2010. Com base na revisão, pode se perceber que ainda existem muitas questões sem respostas sobre a farmacologia da buspirona. Somente a descrição do mecanismo de ação é insuficiente para explicar todos os efeitos produzidos pela buspirona. Além disso, em nossos estudos farmacológicos demonstramos que a buspirona apresenta efeitos anticonvulsivantes e neuroprotetores em camundongos no modelo de convulsão induzido por pilocarpina. Existem poucas informações na literatura sobre o mecanismo de ação que explicaria os efeitos adversos da buspirona, bem como suas propriedades anticonvulsivantes e neuroprotetoras. Dessa forma, são necessários mais estudos para fornecer as informações necessárias, bem como para esclarecer as suas propriedades farmacológicas, contribuindo com o conhecimento dos profissionais, a fim de prevenir os efeitos adversos durante o tratamento clínico com a buspirona.
Buspirone was the first drug in the class of azapirones and is the only one marketed in Brazil. The objective of this study was to conduct a literature review on the pharmacology of buspirone, as well as to demonstrate its neuroprotective and anticonvulsant effects in the model of seizures induced by pilocarpine. To this end, we employed the keywords buspirone, action mechanism, pharmacokinetics, indications, adverse effects, nomenclature and structure to perform a search of the literature, through MEDLINE and LILACS, and inserted the experimental results obtained in mice pretreated with buspirone in the model of seizures induced by pilocarpine. The search included all full articles, abstracts, case studies, pre-clinical and clinical studies in Portuguese and English, between the years 1982 and 2010. The review revealed that there are still many unanswered questions about the pharmacology of buspirone. A description of the mechanism of action alone is insufficient to explain all the effects produced by buspirone. Moreover, our pharmacological studies have shown that buspirone has anticonvulsant and neuroprotective effects in a mouse model of seizures induced by pilocarpine. There is little information in the literature about mechanisms that would explain either the adverse effects of buspirone or its anticonvulsant and neuroprotective properties. Thus, further studies are needed to provide the necessary information, as well as to clarify its pharmacological properties, in order to enable professionals to prevent adverse effects during clinical treatment with buspirone.
Asunto(s)
Buspirona/efectos adversos , Buspirona/farmacocinética , Buspirona/farmacologíaRESUMEN
Cocaine is used worldwide and considered a public health problem. Relapse from addiction is one of the difficulties faced by cocaine users, and in most cases according to the period of abstinence, users may present symptoms such as anxiety or depression. To evaluate the anxiety-like behavior induced by different periods, rats were treated for 7 days with cocaine 20 mg/kg, i.p., and 24 h, 7 and 21 days after drug withdrawal were submitted to the elevated plus maze (EPM) and the open field (OF) tests. In different protocol, propranolol (10 mg/kg, i.p.), ondansetron (4 mg/kg, i.p.) and buspirone (5 mg/kg, i.p.) were administered once after 24 h and 7 days of abstinence from cocaine to evaluate possible reversal or attenuation of the symptoms caused by cocaine withdrawal. EPM results showed a reduction in all parameters after 24 h and 7 days of the last exposure to cocaine, indicating anxiety-like behavior. In the OF test, 24 h and 7 days of abstinence showed increased locomotor activity, while in the withdrawal 21 days the animals not alter the locomotor activity. The administration of propranolol, ondansetron or buspirone after a 24 h abstinence period reduced the animals anxiety in the EPM, and in the OF all drugs were able to reduce locomotor activity. After abstinence 7 d, the drugs reduced locomotor activity in the OF, in the EMP propranolol and ondansetron reversed the anxiogenic effect induced by cocaine. These results suggest that the treatment of anxyogenic effects of abstinence from cocaine is dependent on the period of the withdrawal.
Asunto(s)
Ansiolíticos/uso terapéutico , Ansiedad/tratamiento farmacológico , Conducta Animal/efectos de los fármacos , Cocaína/efectos adversos , Síndrome de Abstinencia a Sustancias/tratamiento farmacológico , Animales , Ansiolíticos/farmacología , Ansiedad/inducido químicamente , Buspirona/farmacología , Buspirona/uso terapéutico , Masculino , Actividad Motora/efectos de los fármacos , Ondansetrón/farmacología , Ondansetrón/uso terapéutico , Propranolol/farmacología , Propranolol/uso terapéutico , Ratas , Ratas WistarRESUMEN
There is growing interest in zebrafish as a model organism in behavioral pharmacology research. Several anxiety behaviors have been characterized in zebrafish, but the effect of anxiolytic drugs on these parameters has been scarcely studied. The purpose of this work was to assess the predictive validity of acute treatment with anxiolytic drugs on behavioral parameters of anxiety. In the first task we simultaneously observed behavior of adult zebrafish on four parameters: height in the tank, locomotion, color, and shoal cohesion. The second task was the assessment of light/dark preference for 5 min. The benzodiazepines clonazepam, bromazepam, diazepam, and a moderate dose of ethanol significantly reduced shoal cohesion. Buspirone specifically increased zebrafish exploration of higher portions of the tank. In the light/dark task, all benzodiazepines, buspirone, and ethanol increased time spent in the light compartment. After treatment with anxiolytics, fish typically spent more than 60s and rarely less than 40s in the light compartment whereas controls (n=45) spent 33.3±14.4s and always less than 60s in the light compartment. Propranolol had no clear effects in these tasks. These results suggest that light/dark preference in zebrafish is a practical, low-cost, and sensitive screening task for anxiolytic drugs. Height in the tank and shoal cohesion seem to be useful behavioral parameters in discriminating different classes of these drugs.
Asunto(s)
Ansiolíticos/farmacología , Benzodiazepinas/farmacología , Buspirona/farmacología , Etanol/farmacología , Actividad Motora/efectos de los fármacos , Desempeño Psicomotor/efectos de los fármacos , Animales , Oscuridad , Femenino , Iluminación , Masculino , Actividad Motora/fisiología , Desempeño Psicomotor/fisiología , Pez CebraRESUMEN
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.
Asunto(s)
Buspirona/farmacología , Hipocampo/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Convulsiones/tratamiento farmacológico , Convulsiones/fisiopatología , Agonistas de Receptores de Serotonina/farmacología , Animales , Anticonvulsivantes/administración & dosificación , Anticonvulsivantes/farmacología , Buspirona/administración & dosificación , Catalasa/metabolismo , Hipocampo/fisiopatología , Peroxidación de Lípido/efectos de los fármacos , Masculino , Nitritos/metabolismo , Estrés Oxidativo/fisiología , Pilocarpina , Ratas , Ratas Wistar , Convulsiones/inducido químicamente , Agonistas de Receptores de Serotonina/administración & dosificación , Estado Epiléptico/inducido químicamente , Estado Epiléptico/tratamiento farmacológico , Estado Epiléptico/fisiopatología , Superóxido Dismutasa/metabolismo , Factores de TiempoRESUMEN
In the present study, we determined the incidence and effects of season and weather on clinical manifestations of endophyte-infected ryegrass toxicity, performed chemical detection and pharmacological bioassays on ryegrass extracts, and conducted trials on: (i) effects of domperidone or metochlopramide on ovarian inactivity induced by endophyte-infected ryegrass; (ii) efficacy of buspirone or dihydrochloro phenyl piperazine (m-CPP) for preventing suppressed milk production induced by endophyte-infected ryegrass; and (iii) efficacy of domperidone to induce ovulation during winter anestrus. Mares with toxicosis had prolonged gestation, embryonic losses, dystocia, poor mammary gland development, low milk production, prolonged uterine involution, and suppressed ovarian activity. Foals had respiratory failure, abnormalities of the skin, umbilicus, bone, and muscle, failure to thrive, blindness, testicular atrophy, and decreased serum total immunoglobulin concentrations. Endophyte-infected ryegrass and the incidence of toxicosis were correlated (r=0.861, P=0.03). Ergot alkaloids were not detected in extracts of endophyte-infected ryegrass by either thin-layer chromatography or spectrophotometry, but their presence was inferred in bioassays of extracts (dose-related increases in the contractile response of rat uterus). Mares given metoclopropamide (0.6 mg/kg/d), given orally every 8h for up to 7d) ovulated earlier (4-7d vs. 15-18d, P<0.001) than those given domperidone (1.1mg/kg/d) orally for up to 18d). Although both metoclopropamide and domperidone induced milk production, the latter did not induce ovarian cyclicity in healthy mares during seasonal anestrus. Based on these findings, we inferred that endophyte-infected ryegrass is associated with ergot alkaloid intoxication in horse.
Asunto(s)
Alimentación Animal/análisis , Alcaloides de Claviceps/aislamiento & purificación , Alcaloides de Claviceps/toxicidad , Enfermedades de los Caballos/inducido químicamente , Lolium , 2-Piridinilmetilsulfinilbencimidazoles , Animales , Bioensayo , Buspirona/farmacología , Femenino , Contaminación de Alimentos , Hongos/aislamiento & purificación , Hongos/metabolismo , Enfermedades de los Caballos/epidemiología , Caballos , Lactancia/efectos de los fármacos , Lansoprazol , Piperazinas/farmacología , Lluvia , Estaciones del Año , Factores de TiempoRESUMEN
It has been recently shown that the supersensitivity of distal segments of the rat tail artery to phenylephrine after chemical sympathectomy with reserpine results from the appearance of alpha(1D)-adrenoceptors. It is known that both alpha(1A)- and alpha(1D)-adrenoceptors are involved in the contractions of proximal portions of the rat tail artery. Therefore, this study investigated whether sympathectomy with reserpine would induce supersensitivity in proximal segments of the rat tail artery, a tissue in which alpha(1D)-adrenoceptors are already functional. Proximal segments of tail arteries from reserpinised rats were three- to sixfold more sensitive to phenylephrine and methoxamine than were arteries from control rats (n = 6-2; p < 0.05). The imidazolines N-[5-(4,5-Dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide hydrobromide (A-61603) and oxymetazoline, which activate selectively alpha(1A)-adrenoceptors, were equipotent in tail arteries from control and reserpinised rats (n = 4-2; p < 0.05), whereas buspirone, which activates selectively alpha(1D)-adrenoceptor, was approximately 4-fold more potent in tail arteries from reserpinised rats (n = 4-6; p < 0.05). Prazosin (nonselective) and 5-methylurapidil (alpha(1A)-selective), were competitive antagonists of contractions induced by phenylephrine and were equipotent in tail arteries from control and reserpinised rats (n = 4-6). The selective alpha(1D)-adrenoceptor antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione dihydrochloride (BMY-7378) presented similar complex antagonism in tail arteries from control and reserpinised rats, with Schild slopes much lower than 1.0 (p < 0.05, n = 4-6). Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) revealed that mRNA encoding alpha(1A)-and alpha(1B)-adrenoceptors are similarly distributed in tail arteries from control and reserpinised rats, whereas mRNA for alpha(1D)-adrenoceptors is twice more abundant in the tail artery from reserpinised rats. In conclusion, the supersensitivity induced by reserpine is related only to alpha(1D)-adrenoceptors, even in tissues where this receptor subtype is already present and functional. Only the use of subtype-selective alpha(1)-adrenoceptor agonists detected the increased alpha(1D)-adrenoceptor component after reserpinisation, as the antagonists behaved similarly in tail arteries from control and reserpinised rats.
Asunto(s)
Arterias/inervación , Músculo Liso Vascular/fisiología , Receptores Adrenérgicos alfa 1/biosíntesis , Cola (estructura animal)/irrigación sanguínea , Agonistas de Receptores Adrenérgicos alfa 1 , Antagonistas de Receptores Adrenérgicos alfa 1 , Animales , Arterias/efectos de los fármacos , Arterias/metabolismo , Buspirona/farmacología , Expresión Génica , Imidazoles/farmacología , Técnicas In Vitro , Masculino , Metoxamina/farmacología , Contracción Muscular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Oximetazolina/farmacología , Fenilefrina/farmacología , Piperazinas/farmacología , Prazosina/farmacología , ARN Mensajero/biosíntesis , Ratas , Ratas Wistar , Reserpina/farmacología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Simpatectomía , Tetrahidronaftalenos/farmacologíaRESUMEN
RATIONALE: Administration of 5-hydroxytryptamine (5-HT)1A and 5-HT2A receptor agonists into the dorsal periaqueductal gray (DPAG) inhibits escape, a defensive behavior associated with panic attacks. Long-term treatment with the antipanic compound imipramine enhances the DPAG 5-HT1A- and 5-HT2A-receptor-mediated inhibition of escape, implicating these receptors in the mode of action of panicolytic drugs. OBJECTIVES: In the present study, we investigated whether the inhibitory effect on escape elicited by the intra-DPAG injection of 5-HT1A and 5-HT2A receptor agonists is also enhanced after treatment with fluoxetine, another widely used antipanic drug. The effects of fluoxetine were compared to those of buspirone, an anxiolytic drug without major effect on panic disorder. METHODS: Male Wistar rats, subchronically (3-6 days) or chronically (21-24 days) treated with fluoxetine (10 mg/kg i.p.) or chronically treated with buspirone (0.3 mg/kg i.p.), were intra-DPAG injected with 5-HT (20 nmol), the 5-HT1A receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT; 8 nmol) or the preferential 5-HT2A receptor agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl) piperazine dihydrochloride (DOI; 16 nmol). The intensity of electrical current that applied to the DPAG-evoked escape behavior was measured before and after the microinjection of these agonists. RESULTS: The electrical current necessary to produce escape was increased after the microinjection of the three 5-HT receptor agonists in all groups of animals tested. However, this panicolytic-like effect was significantly higher in animals receiving long-term treatment with fluoxetine. CONCLUSIONS: The results suggest that facilitation of the 5-HT1A- and 5-HT2A-receptor-mediated inhibition of DPAG neuronal activity is implicated in the beneficial effect of antidepressants in panic disorder.
Asunto(s)
Ansiolíticos/farmacología , Buspirona/farmacología , Fluoxetina/farmacología , Sustancia Gris Periacueductal/fisiología , Receptor de Serotonina 5-HT1A/efectos de los fármacos , Receptor de Serotonina 5-HT2A/efectos de los fármacos , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , 8-Hidroxi-2-(di-n-propilamino)tetralin/metabolismo , Anfetaminas/administración & dosificación , Anfetaminas/farmacología , Animales , Ansiolíticos/administración & dosificación , Buspirona/administración & dosificación , Fluoxetina/administración & dosificación , Masculino , Microinyecciones , Ratas , Ratas Wistar , Serotonina/metabolismo , Agonistas de Receptores de Serotonina/metabolismo , Inhibidores Selectivos de la Recaptación de Serotonina/administración & dosificaciónRESUMEN
The dorsal periaqueductal gray matter (DPAG) has been implicated in the mediation of escape, a defensive behavior associated with panic disorder (PD). Chronic treatment with the anti-panic agent imipramine enhances the inhibitory effect on escape evoked by DPAG electrical stimulation of intra-DPAG administration of the 5-HT1A receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and the preferential 5-HT 2 A receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI). In the present study we further explore the hypothesis that sensitization of 5-HT1A and 5-HT 2 A receptors in the DPAG is involved in the anti-panic effect of imipramine. To this end, Wistar rats, subchronically or chronically treated with imipramine, were intra-DPAG injected with 8-OH-DPAT (0.4 or 3.2 nmoles) or DOI (16 nmoles), and tested in the elevated T-maze. In addition to its possible relevance to panic disorder, this test also measures inhibitory avoidance, a behavior that has been associated with generalized anxiety disorder (GAD). The effects of these 5-HT agonists in the DPAG were also investigated in animals chronically injected with buspirone, a drug clinically effective in treating GAD, but not PD. The results showed that intra-DPAG administration of the highest dose of 8-OH-DPAT and of DOI inhibited escape, and this panicolytic-like effect was significantly higher in animals previously treated chronically, but not subchronically, with imipramine. 8-OH-DPAT (0.4 nmole), although not affecting escape in animals systemically treated with saline, had a panicolytic-like effect in those receiving long-term treatment with imipramine. Microinjection of 8-OH-DPAT (3.2 nmoles), but not of DOI, impaired inhibitory avoidance, and this anxiolytic effect did not differ between animals treated with saline or imipramine. Chronic buspirone did not change the effect of 8-OH-DPAT and DOI on inhibitory avoidance and escape. Therefore, chronic imipramine seems to sensitize both 5-HT1A and 5-HT 2 A receptors in the DPAG, strengthening the view that these receptors are involved in the mode of action of anti-panic drugs.
Asunto(s)
Antidepresivos Tricíclicos/farmacología , Ansiedad/tratamiento farmacológico , Ansiedad/psicología , Imipramina/farmacología , Sustancia Gris Periacueductal/metabolismo , Receptor de Serotonina 5-HT1A/efectos de los fármacos , Receptor de Serotonina 5-HT2A/efectos de los fármacos , 8-Hidroxi-2-(di-n-propilamino)tetralin/farmacología , Anfetaminas/farmacología , Animales , Buspirona/farmacología , Masculino , Actividad Motora/efectos de los fármacos , Sustancia Gris Periacueductal/efectos de los fármacos , Ratas , Ratas Wistar , Agonistas de Receptores de Serotonina/farmacologíaRESUMEN
Serotonin 5-HT(1A) receptors were characterized in rat resting lymphocytes obtained by cardiac puncture with the use of the ligand [3H]8-hydroxy-2-(di-n-propylamino)tetralin. Selectivity of the specific binding was demonstrated by inhibition experiments with various serotonergic and nonserotonergic drugs. The rank order of potency for inhibition was WAY-100478>pindobind>NAN-190>buspirone>imipramine>serotonin. While pimozide, desipramine, nomifensine, haloperidol and sulpiride did not inhibit the binding. Kinetic parameters calculated from saturation experiments indicated one site of interaction, with an equilibrium dissociation constant of 2.50 nM and maximum binding capacity of 487.21 nmol/10(6) cells. Complete dissociation was obtained with serotonin as the displacement agent, and equilibrium dissociation constant calculated by association and dissociation experiments was 2.03 nM. Thus, serotonin 5-HT(1A) receptors are present in resting lymphocytes. The in vivo administration of the mitogens lipopolysacharide (0.1 mg/kg, 18 h) or concanavalin A (0.2 mg/kg, 18 h) increased the number of sites. The elevation produced by the latter was of higher magnitude than that of lipopolysacharide, and two sites of the binding were determined by isotopic dilution. Immobilization stress (1 h daily for 7 days) also resulted in a significant increase of binding capacity, but was smaller than that produced by the mitogens. The affinity of binding was not affect by the treatments. The results indicate that serotonin 5-HT(1A) receptors are modulated by unspecific and specific immune system activation, as well as by a potent stress condition, which might result in relevant functional modifications in the response of rat lymphocytes.
Asunto(s)
8-Hidroxi-2-(di-n-propilamino)tetralin/sangre , Concanavalina A/farmacología , Inmovilización/fisiología , Linfocitos/metabolismo , Agonistas de Receptores de Serotonina/sangre , 8-Hidroxi-2-(di-n-propilamino)tetralin/farmacología , Animales , Sitios de Unión/efectos de los fármacos , Sitios de Unión/fisiología , Unión Competitiva/efectos de los fármacos , Unión Competitiva/fisiología , Buspirona/metabolismo , Buspirona/farmacología , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Cinética , Lipopolisacáridos/metabolismo , Linfocitos/efectos de los fármacos , Linfocitos/fisiología , Masculino , Ensayo de Unión Radioligante , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina/sangre , Receptores de Serotonina 5-HT1 , Agonistas de Receptores de Serotonina/farmacología , Estrés Fisiológico/sangre , Estrés Fisiológico/inmunologíaRESUMEN
Buspirone (busp) a piperazinyl derivative with anxiolytic properties is a partial agonist on 5-HT1A with affinity for D2-like dopaminergic receptors (RD2). The objective of this study was to verify the effects of busp on RD2. Female Wistar rats 150-200 g were treated with busp (5 and 10 mg/kg, p.o.) 1 or 2 times daily for 7 days. Controls (C) received saline. The density of RD2 (fmol/mg protein) was determined through binding assays in striatum (ST) using [3H]-spiroperidol as radioligand. No alteration in Bmax or Kd values were seen after busp administration once a day. However, a RD2 upregulation of 55 % increase was observed after busp 2 times a day with no change in Kd values. The results showed that busp interact not only with serotonergic, but also with dopaminergic system.
Asunto(s)
Buspirona/farmacología , Cuerpo Estriado/efectos de los fármacos , Receptores de Dopamina D2/efectos de los fármacos , Serotoninérgicos/farmacología , Animales , Buspirona/administración & dosificación , Cuerpo Estriado/metabolismo , Femenino , Ratas , Ratas Wistar , Receptores de Dopamina D2/metabolismo , Serotoninérgicos/administración & dosificaciónRESUMEN
Previous studies have shown that rats withdrawn from long-term treatment with dopamine receptor blockers exhibit dopaminergic supersensitivity, which can be behaviorally evaluated by enhanced general activity observed in an open-field. Recently, it has been reported that co-treatment with the non-benzodiazepine anxiolytic buspirone attenuates the development of haloperidol-induced dopaminergic supersensitivity measured by open-field behavior of rats. The aims of the present study were: 1) to determine, as previously reported for rats, if mice withdrawn from long-term neuroleptic treatment would also develop dopaminergic supersensitivity using open-field behavior as an experimental paradigm, and 2) to examine if acute buspirone administration would attenuate the expression of this behavioral dopaminergic supersensitivity. Withdrawal from long-term haloperidol treatment (2.5 mg/kg, once daily, for 20 days) induced a significant (30%) increase in ambulation frequency (i.e., number of squares crossed in 5-min observation sessions) but did not modify rearing frequency or immobility duration in 3-month-old EPM-M1 male mice observed in the open-field apparatus. Acute intraperitoneal injection of buspirone (3.0 and 10 but not 1.0 mg/kg, 12-13 animals per group) 30 min before open-field exposure abolished the increase in locomotion frequency induced by haloperidol withdrawal. These data suggest that the open-field behavior of mice can be used to detect dopaminergic supersensitivity, whose expression is abolished by acute buspirone administration.
Asunto(s)
Ansiolíticos/farmacología , Buspirona/farmacología , Dopamina/farmacología , Hipersensibilidad a las Drogas/etiología , Locomoción/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Antagonistas de Dopamina/farmacología , Interacciones Farmacológicas , Discinesia Inducida por Medicamentos/metabolismo , Haloperidol/farmacología , Masculino , Ratones , Conducta Estereotipada/efectos de los fármacosRESUMEN
Previous reports indicate that the behavioural effects (including anxiolytic-like actions, hypothermia, "serotonergic syndrome," maternal behaviour and aggression and reduction in ambulation) of the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), are completely blocked in lactating rats. The present study compares the behavioural effects of buspirone (1.25, 2.5 and 5.0 mg/kg) and diazepam (0.5, 1.0, 2.0 and 4.0 mg/kg) between ovariectomized and mid-lactating rats. The study was carried out on Wistar female rats under inverted light/dark cycle conditions, by using the burying behaviour paradigm, the elevated plus maze and a general activity test. In both ovariectomized and lactating rats, diazepam produced a dose-dependent reduction in burying behaviour and an increase in the time spent in open arms, responses interpreted as anxiolytic. Buspirone at all doses (1.25, 2.5 and 5.0 mg/kg) produced clear motor impairments in lactating, but not in ovariectomized animals, indicating that the effects of this drug on the anxiety paradigms are unspecific. Diazepam, by contrast, at the highest dose (4.0 mg/kg) similarly inhibited ambulation in both conditions. In the elevated plus maze, control lactating subjects spent more time in the open arms compared with saline-treated ovariectomized subjects, suggesting an anxiolytic-like effect of lactation per se. The present results support the idea that some behavioural actions of drugs acting at the serotonergic system vary between ovariectomized and lactating rats.
Asunto(s)
Ansiolíticos/farmacología , Buspirona/farmacología , Diazepam/farmacología , Lactancia/fisiología , Actividad Motora/efectos de los fármacos , Ovariectomía , Animales , Relación Dosis-Respuesta a Droga , Femenino , Actividad Motora/fisiología , Ratas , Ratas WistarRESUMEN
In order to further validate the recently developed marmoset (Callithrix penicillata) predator confrontation model of fear and anxiety, we investigated the behavioral effects of buspirone with this method. The apparatus consisted of three parallel arms connected at each end to a perpendicular arm, forming a figure-eight continuous maze. A taxidermized wild oncilla cat (Felis tigrina) was positioned facing a corner of the parallel arms, alternating between the left or right side of the maze among animals tested. All subjects were first submitted to seven 30-min maze habituation trials (HTs) in the absence of the predator, and then to five randomly assigned treatment trials (TTs) in the presence of the predator: three buspirone sessions (0.1, 0.5 and 1.0 mg/kg), saline and sham injection controls. Twenty minutes after treatment administration, the animal was released into the maze and had free access to the apparatus for 30 min. All trials were taped for later behavioral analysis. Buspirone significantly decreased the frequency of scent marking, while increasing the time spent in proximity to the 'predator' stimulus, indicating an anxiolytic effect. Neither locomotor activity, exposure to a novel environment, stimulus location and habituation, nor gender influenced the effects of the drug treatments. These results further validate this method and demonstrate the potential usefulness of this ethologically based paradigm to test anxiety and fear-induced avoidance in nonhuman primates and its susceptibility to anxiolytic pharmacological manipulations.
Asunto(s)
Ansiolíticos/farmacología , Ansiedad/tratamiento farmacológico , Buspirona/farmacología , Conducta Exploratoria/efectos de los fármacos , Miedo/efectos de los fármacos , Animales , Ansiolíticos/uso terapéutico , Ansiedad/psicología , Buspirona/uso terapéutico , Callithrix , Conducta Exploratoria/fisiología , Miedo/fisiología , Miedo/psicología , Femenino , Masculino , Actividad Motora/efectos de los fármacos , Actividad Motora/fisiologíaRESUMEN
The action of diazepam (0.0, 1.0, and 2.0 mg/kg) and the serotonergic compounds buspirone (0.0, 2.5, and 5.0 mg/kg) and 8-OH-DPAT (0.0, 0.1, and 1.0 mg/kg) on maternal behavior and aggression were studied. An activity test was made after these treatments to control for unspecific actions due to motor impairment. Diazepam and buspirone dose-dependently inhibited the expression of maternal aggression and the active components of maternal behavior such as retrieving and nest building. 8-OH-DPAT did not affect these behaviors. 8-OH-DPAT (1.0 mg/kg) provoked the serotonergic syndrome and hypothermia; however, ovariectomized animals showed more signs of the syndrome and a decrease in body temperature after 8-OH-DPAT than lactating rats. Buspirone, but not the other anxiolytics, reduced motor activity. The role of drugs acting at the serotonergic, dopaminergic, and GABA-benzodiazepine systems in the control of maternal behavior and aggression is discussed.