Análises farmacogenômica e funcional do efeito do biperideno nas interações das vias colinérgicas e dopaminérgicas nos transtornos por uso de etanol e cocaína
Date
2022-04-20
Authors
Palombo, Paola [UNIFESP]
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Santos, Paulo Caleb Junior de Lima [UNIFESP]
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Tese de doutorado
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Abstract
Os transtornos por uso de cocaína e de etanol são grandes problemas de saúde pública no Brasil e no mundo. Os fármacos utilizados para o tratamento destes transtornos são escassos e ineficazes para evitar a recaída ao uso destas drogas. Os sistemas dopaminérgico e colinérgico estão envolvidos nos mecanismos relacionados aos transtornos por uso de substâncias (TUS). Assim, fármacos que atuem no equilíbrio entre esses sistemas de neurotransmissão, podem ser promissores para o tratamento dos TUS. Estudos sugerem que o biperideno, um antagonista muscarínico M1pode ser uma nova ferramenta farmacológica para esse tratamento. Dessa forma, o objetivo do presente estudo foi avaliar a participação dos sistemas dopaminérgico e muscarínico, assim como os efeitos do tratamento com o biperideno sobre comportamentos relacionados ao transtorno por uso de cocaína e etanol, em roedores. Para isso, investigamos o efeito do biperideno sobre: a) a autoadministração intravenosa de cocaína; b) nas concentrações de dopamina e de seus metabólitos em ratos submetidos ao teste de reexposição ao contexto associado a autoadministração de cocaína; c) na preferência condicionada por lugar (PCL) induzida por etanol em camundongos; d) no número de células Fos positivas, da borda e centro do núcleo acumbens em camundongos submetidos ao teste de expressão da PCL, induzida por etanol; e) nas concentrações teciduais de dopamina e de seus metabólitos em camundongos submetidos ao teste da PCL induzida pelo etanol; f) no consumo de etanol no paradigma de livre escolha de etanol ou água; g) no teste de reconhecimento de objetos de camundongos e h) na função motora de camundongos. Por fim, avaliamos, a expressão dos genes que codificam os receptores dopaminérgicos D1 (DrD1) e D2 (DrD2), muscarínicos M1 (mAChR M1) e M4 (mAChR M4), e da enzima Catecol O-Metiltransferase (COMT) em ratos submetidos a um protocolo de exposição prolongada ao etanol (câmara de vapor) ou à cocaína (acesso estendido a autoadministração de cocaína por 6 horas). Em resumo, nossos resultados demonstraram que a administração de biperideno, na dose de 10 mg/Kg, atenuou a motivação e a reexposição ao contexto associado a autoadministração de cocaína; porém não afetou o consumo em binge dessa substância. Em relação ao etanol, observamos que esse fármaco, nas doses de 1, 5 e 10 mg/kg, atenuou a expressão da PCL de etanol. Esse efeito foi acompanhado pelo aumento no número de células positivas para a proteína Fos e na taxa de utilização de dopamina no núcleo acumbens. Evidenciamos, também, que a administração de biperideno promoveu prejuízo nos testes de reconhecimento de objetos, uma e vinte e quatro horas após o treino, porém não causou déficit motor e nem alteração na quantidade consumida de etanol no protocolo de livre escolha. Por fim, o protocolo de acesso estendido da autoadministração de cocaína, promoveu aumento na expressão dos genes do receptor D1 e M1, enquanto o protocolo de acesso restrito promoveu aumento apenas na expressão do gene D1. Já o protocolo de exposição à câmara de vapor, promoveu aumento apenas na expressão do gene do receptor M1. Dessa forma, nossos resultados sugerem que o biperideno possui potencial terapêutico para o tratamento do transtorno por uso de cocaína e etanol e pode estar relacionado a diminuição na expressão gênica do receptor muscarínico M1.
Cocaine and ethanol use disorders are major public health problems in Brazil and worldwide. The drugs used for the treatment of these disorders are scarce and ineffective to prevent relapse to the use of these drugs. The dopaminergic and cholinergic systems are involved in the mechanisms related to substance use disorders (SUD). Thus, drugs that act on the balance between these neurotransmission systems may be promising for the treatment of SUD. Studies suggest that biperiden, an M1 muscarinic antagonist, may be a new pharmacological tool for this treatment. Thus, the aim of the present study was to evaluate the participation of the dopaminergic and muscarinic systems, as well as the effects of treatment with biperiden on behaviors related to cocaine and ethanol use disorder in rodents. For this, we investigated the effect of biperiden on: a) intravenous cocaine self-administration; b) on the concentrations of dopamine and its metabolites in rats submitted to the context-induced cocaine reinstatement test; c) ethanol-induced conditioned place preference (PCL) in mice; d) on the number of Fos positive cells, at the core and shell of the nucleus accumbens in mice submitted to the PCL expression test, induced by ethanol; e) tissue concentrations of dopamine and its metabolites in mice submitted to the ethanol-induced PCL test; f) ethanol consumption in the paradigm of free choice of ethanol or water; g) in the object recognition test of mice and h) in the motor function of mice. Finally, we evaluated the expression of genes encoding the dopaminergic receptors D1 (DrD1) and D2 (DrD2), muscarinic M1 (mAChR M1) and M4 (mAChR M4), and the enzyme Catechol O-Methyltransferase (COMT) in rats submitted to a protocol of prolonged exposure to ethanol (vapor chamber) or cocaine (extended access to cocaine self-administration for 6 hours). In summary, our results demonstrated that the administration of biperiden, at a dose of 10 mg/kg, attenuated context-induced motivation and reinstatement of cocaine seeking; however, it did not affect binge consumption of this substance. Regarding ethanol, we observed that this drug, at doses of 1, 5 and 10 mg/kg, attenuated the expression of ethanol PCL. This effect was accompanied by an increase in the number of Fos-positive cells and in the rate of dopamine utilization in the nucleus accumbens. We also showed that the administration of biperiden promoted impairment in object recognition tests, one and twenty-four hours after training, but did not cause motor deficit or change in the amount of ethanol consumed in the free choice protocol. Finally, the extended access protocol of cocaine self-administration promoted an increase in the expression of D1 and M1 receptor genes, while the restricted access protocol promoted an increase only in the expression of the D1 gene. The protocol of exposure to the vapor chamber promoted an increase only in the expression of the M1 receptor gene. Thus, our results suggest that biperiden has therapeutic potential for the treatment of cocaine and ethanol use disorder and may be related to a decrease in the gene expression of the M1 muscarinic receptor.
Cocaine and ethanol use disorders are major public health problems in Brazil and worldwide. The drugs used for the treatment of these disorders are scarce and ineffective to prevent relapse to the use of these drugs. The dopaminergic and cholinergic systems are involved in the mechanisms related to substance use disorders (SUD). Thus, drugs that act on the balance between these neurotransmission systems may be promising for the treatment of SUD. Studies suggest that biperiden, an M1 muscarinic antagonist, may be a new pharmacological tool for this treatment. Thus, the aim of the present study was to evaluate the participation of the dopaminergic and muscarinic systems, as well as the effects of treatment with biperiden on behaviors related to cocaine and ethanol use disorder in rodents. For this, we investigated the effect of biperiden on: a) intravenous cocaine self-administration; b) on the concentrations of dopamine and its metabolites in rats submitted to the context-induced cocaine reinstatement test; c) ethanol-induced conditioned place preference (PCL) in mice; d) on the number of Fos positive cells, at the core and shell of the nucleus accumbens in mice submitted to the PCL expression test, induced by ethanol; e) tissue concentrations of dopamine and its metabolites in mice submitted to the ethanol-induced PCL test; f) ethanol consumption in the paradigm of free choice of ethanol or water; g) in the object recognition test of mice and h) in the motor function of mice. Finally, we evaluated the expression of genes encoding the dopaminergic receptors D1 (DrD1) and D2 (DrD2), muscarinic M1 (mAChR M1) and M4 (mAChR M4), and the enzyme Catechol O-Methyltransferase (COMT) in rats submitted to a protocol of prolonged exposure to ethanol (vapor chamber) or cocaine (extended access to cocaine self-administration for 6 hours). In summary, our results demonstrated that the administration of biperiden, at a dose of 10 mg/kg, attenuated context-induced motivation and reinstatement of cocaine seeking; however, it did not affect binge consumption of this substance. Regarding ethanol, we observed that this drug, at doses of 1, 5 and 10 mg/kg, attenuated the expression of ethanol PCL. This effect was accompanied by an increase in the number of Fos-positive cells and in the rate of dopamine utilization in the nucleus accumbens. We also showed that the administration of biperiden promoted impairment in object recognition tests, one and twenty-four hours after training, but did not cause motor deficit or change in the amount of ethanol consumed in the free choice protocol. Finally, the extended access protocol of cocaine self-administration promoted an increase in the expression of D1 and M1 receptor genes, while the restricted access protocol promoted an increase only in the expression of the D1 gene. The protocol of exposure to the vapor chamber promoted an increase only in the expression of the M1 receptor gene. Thus, our results suggest that biperiden has therapeutic potential for the treatment of cocaine and ethanol use disorder and may be related to a decrease in the gene expression of the M1 muscarinic receptor.