ABSTRACT
PURPOSE: We investigated what kinds of neurotransmitters are related with electroacupuncture (EA) analgesia in an arthritic pain model of rats. MATERIALS AND METHODS: One hundred rats were assigned to six groups: control, EA, opioid, adrenergic, serotonin and dopamine group. A standardized model of inflammatory arthritis was produced by injecting 2% carrageenan into the knee joint cavity. EA was applied to an acupoint for 30 min in all groups except fo the control group. In the opioid, adrenergic, serotonin and dopamine groups, each receptor antagonist was injected intraperitoneally to their respective group before initiating EA. RESULTS: In the opioid receptor antagonist group, adrenergic receptor antagonist group, serotonin receptor antagonist group, dopamine receptor antagonist group and the control group weight-bearing force decreased significantly from 30 min to 180 min after EA in comparison with the EA group. CONCLUSION: The analgesic effects of EA are related to opioid, adrenergic, serotonin and dopamine receptors in an arthritic pain model of rats.
Subject(s)
Animals , Male , Rats , Acupuncture Analgesia/methods , Adrenergic Antagonists/therapeutic use , Arthritis/chemically induced , Carrageenan/toxicity , Dopamine Antagonists/therapeutic use , Electroacupuncture/methods , Neurotransmitter Agents/metabolism , Pain/drug therapy , Rats, Sprague-Dawley , Receptors, Adrenergic/metabolism , Receptors, Dopamine/metabolism , Receptors, Opioid/antagonists & inhibitors , Receptors, Serotonin/metabolism , Serotonin Antagonists/therapeutic useABSTRACT
O autor faz uma revisão das propriedades farmacocinéticas e farmacodinâmicas da risperidona, um novo antipsicótico pertencente à classe dos "antagonistas da serotonina/dopamina". A risperidona é rapidamente absorvida, tem um início rápido de ação, a qual dura cerca de 24 h. Seu metabólico principal, a 9-hidroxirisperidona, tem um perfil de ação semelhante ao da droga-mãe. O mecanismo primário de ação da risperidona é um potente bloqueio de receptores 5-HT2, o qual é 10 vezes maior do que sobre D2. A potente ação sobre 5HT2 e pequena ação sobre D2 produzem aumento da atividade dopaminérgica a nível de córtices pré-frontal, o que melhoraria os sintomas negativos. Em doses um pouco maiores, a risperidona produz bloqueio nos receptores D2 do sistema mesolímbico, o que produziria melhora dos sintomas positivos. Nessa faixa de dose, a risperidona não produz efeito bloqueador importante sobre os receptores D2 localizados no gânglio basal e portanto causa poucos ou nenhum sintomas extrapiramidais. A ação antagônica sobre os receptores adrenérgicos Alfa1 (SNC) provoca sedação e sonolência, e a nível periférico hipotensão e taquicardia reflexa. A droga também atua sobre receptores histaminérgicos (H1) a nível de SNC, o que pode aumentar a sedação. A risperidona é praticamente desprovida de ação sobre os receptores colinérgicos e portanto não provoca sintomas anticolinérgicos
Subject(s)
Humans , Receptors, Dopamine/metabolism , Receptors, Serotonin , Risperidone , Serotonin AntagonistsABSTRACT
Fencamfamine (FCF) is a psychostimulant drug classified as an indirect dopamine agonist. In the present study we evaluated the daily variation in plasma FCF concentration and in striatal dopamine receptors. Adult male Wistar rats (250-300 g) maintained on a 12-h light/12-h dark cycle (lights on at 07:00 h) were used. Rats received FCF (10.0 mg/kg, ip) at 09:00, 15:00, 21:00 or 03:00 h and blood samples were collected 30 (N = 6) or 60 (N = 6) min after the injections. Plasma FCF was measured by gas chromatography using an electron capture detector. Two-way ANOVA showed significant differences in FCF concentration when blood samples were collected 30 min after the injection, and the highest value was obtained following injection at 21:00 h. Moreover, at 15:00, 21:00 and 03:00 h, plasma FCF levels were significantly lower 60 min after injection when compared to the 30-min interval. Two other groups of rats (N = 6) were decapitated at 09:00 or 21:00 h and the striata were dissected for the binding assays. The Bmax for [3H]-spiroperidol binding to striatal membranes was higher at 21:00 h, without changes in affinity constant (Kd). In conclusion, plasma FCF levels and dopamine receptors undergo daily variation, a phenomenon that should be considered to explain the circadian time-dependent effects of FCF
Subject(s)
Animals , Male , Rats , Circadian Rhythm , Norbornanes/blood , Receptors, Dopamine/metabolism , Homovanillic Acid/metabolism , Chromatography, Gas , Circadian Rhythm/drug effects , Corpus Striatum/drug effects , Corpus Striatum/metabolism , Injections, Intraperitoneal , Norbornanes/administration & dosage , Norbornanes/pharmacology , Rats, Wistar , Spiperone/metabolism , Time FactorsABSTRACT
We investigated the effect of hyperprolactinemia by long-term domperidone treatment (10.0 mg/kg, single daily dose, ip) on striatal dopamine (DA) receptor sensitivity in male Wistar rats weighing 250-300 g(N=8). Domperidone treatment for days continued to produce an increased in serum concentration of prolactin (PRL) form 17.3 ñ 2.2 to 33.1 ñ 7.3 and from 16.8 ñ 2.3 to 21.9 ñ 2.1, 2 and 72 h after domperidone withdrawal, respectively. Hyperprolactinemia induced by long-term domperidone treatment did not change binding sites (B max) and dissociation constant (Kd) of [3***H]-spiroperidol binding when compared to controls. These results show that byperprolactinemia induced by long-term domperidone treatment does not effect the sensitivity of striatal DA receptors presumably because the effect of neuroleptic drugs is due to their interaction with the receptors and not to the concomitant hyperprolactinemia
Subject(s)
Animals , Rats , Male , Corpus Striatum/metabolism , Domperidone , Hyperprolactinemia/metabolism , Receptors, Dopamine/metabolism , Binding Sites , Hyperprolactinemia/chemically induced , Prolactin/blood , Rats, WistarABSTRACT
Mannich bases and styryl derivatives of imidazolones were evaluated for their antiparkinsonian activity. Two compounds showed potent antiparkinsonian activity. These active compounds also showed binding with dopamine receptors in striatal membrane preparation of rat brain.
Subject(s)
Animals , Antiparkinson Agents , Female , Imidazoles/chemistry , Male , Molecular Structure , Rats , Receptors, Dopamine/metabolismABSTRACT
Dopamine (DA) receptor sensitivity was studied after long-term treatment with haloperidol (0.5 ad 3.0 mg/Kg, ip, single daily dose) or saline in hypophysectomized and infact rats. Haloperidol treatment for seven days produced a 25 to 125% increase in [3H]-spiroperidol binding to strial DA receptors in a dose-dependent fashion. The increase in binding sits (Bmax) was ximilar in both hypophysectomized and intact rats when compared to controls. The present results show that haloperidol treatment
Subject(s)
Rats , Animals , Male , Corpus Striatum/metabolism , Haloperidol/pharmacology , Hypophysectomy , Receptors, Dopamine/metabolismSubject(s)
Animals , Central Nervous System/metabolism , Humans , Mammals/metabolism , Receptors, Adrenergic/metabolism , Receptors, Cell Surface/metabolism , Receptors, Cholinergic/metabolism , Receptors, Dopamine/metabolism , Receptors, GABA-A/metabolism , Receptors, Histamine/metabolism , Receptors, Opioid/metabolism , Receptors, Purinergic/metabolism , Receptors, Serotonin/metabolismABSTRACT
Los estudios con tomografía por emisión de positores y los estudios postmortem indican que por lo menos un grupo de pacientes esquizofrénicos experimentan un aumento en la densidad de los receptores para la dopamina (tipo D2) a nivel central. Recientemente Bondy y Cols. (3) informaron que este incremento también podría observarse en los linfocitos de estos pacientes y que, además, pudiera ser un marcador de vulnerabilidad, es decir, una característica que se hereda junto con la propensión a padecer la enfermedad. Es evidente que, de ser esto cierto, constituiría un hallazgos trascedental en el estudio de tan devastaddora enfermedad. Sin embargo, la evidencia sobre los sitios de un unión dopaminérgicos en los linfocitos es muy controvertida ya que algunos autores (12) no han podido demostrar la unión específica de ligandos dopaminérgicos en estas células, por lo que en este trabajo estudiamos la unión de 3H-espiperona en linfocitos de pacientes esquizofrénicos y en voluntarios sanos
Subject(s)
Adolescent , Adult , Middle Aged , Humans , Schizophrenia, Paranoid/blood , Antipsychotic Agents/metabolism , Lymphocytes , Receptors, Dopamine/metabolism , Schizophrenia, Paranoid/genetics , Schizophrenia, Paranoid/drug therapySubject(s)
Animals , Antiparkinson Agents/metabolism , Corpus Striatum/metabolism , Female , Male , Mice , Piperazines/metabolism , Rats , Receptors, Dopamine/metabolismABSTRACT
Doze pacientes com doença de Parkinson (DP) foram submetidos a privaçäo de sono total. A média de idade dos pacientes era 61 anos e a duraçäo da doença era em média de 5,1 anos (1,5 a 12 anos). Quatro deles usavam apenas anticolinérgico, 4 usavam L-Dopa e 4 combinaçäo de drogas de ambos os grupos. Após privaçäo de sono total por uma única noite foi verificada melhora na rigidez, bradicinesia, alteraçöes de postura e marcha e incapacidade funcional com duraçäo de duas semanas, em comparaçäo com os escores quando da inclusäo no estudo. Näo foi observado efeito sobre o tremor. Em relaçäo aos sintomas depressivos foi verificada melhora com duraçäo de apenas uma semana. Estes resultados sugerem efeito benéfico da privaçäo de sono da DP. Com base em estudos experimentais julgamos que uma explicaçäo possível para estes resultados seja a modificaçäo de receptores dopaminérgicos
Subject(s)
Middle Aged , Humans , Parkinson Disease/therapy , Receptors, Dopamine/metabolism , Sleep DeprivationABSTRACT
O uso crônico de antidepressores tricíclicos aumenta a sensibilidade dos receptores alfa-1 e receptores triptaminérgicos pós-sinápticos, diminuindo a sensibilidade dos receptores ß. O mecanismo destas alteraçöes näo está totalmente elucidado. Além disso, a relaçäo entre os receptores alfa - 2 e dopaminérgicos nas doenças mentais tem sido estudados, sem resultados conclusivos até o momento. Os autores revisam os trabalhos mais recentes acerca do papel destes receptores nas perturbaçöes afetivas