Participação da área septal medial na salivação e resposta dipsogênica induzida pela pilocarpina injetada perifericamente
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Data
2022-03-30
Autores
Marin, Gabrieli Schiavon
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O estudo de substâncias sialagogas tem interesse clínico pela utilidade que elas têm em pacientes com xerostomia. Dentre estas, destacam-se os agonistas colinérgicos, sendo a pilocarpina um dos mais importantes. Pilocarpina injetada perifericamente induz salivação e ingestão de água. A injeção intracerebroventricular (icv) de antagonistas muscarínicos mostrou que a salivação produzida pela pilocarpina injetada intraperitonealmente (ip) depende da ativação de receptores muscarínicos centrais M3, enquanto receptores M1 e M2 participariam da ingestão de água e resposta pressora, porém, as áreas cerebrais responsáveis por estas respostas ainda precisam ser estudadas. Testes combinando-se pilocarpina ip com injeção de antagonistas específicos de diferentes tipos de receptores muscarínicos na área septal medial (ASM) do cérebro de rato são importantes para se definir a participação da ASM nas respostas produzidas pela pilocarpina ip e também para se caracterizar os receptores muscarínicos específicos envolvidos nestas respostas. Assim, o objetivo do projeto foi investigar os efeitos da injeção de antagonistas específicos de receptores M1, M2, M3 e M4 na ASM na salivação e ingestão de água produzida pela pilocarpina injetada ip. Foram utilizados ratos Holtzman, com cânulas de aço inoxidável implantadas na ASM. Investigou-se os efeitos das injeções prévias na ASM de 4-DAMP (antagonista M1/M3) pirenzepina (antagonista muscarínico M1), metoctramina (antagonista muscarínico M2/M4) e tropicamide (antagonista muscarínico M4) sobre a salivação e ingestão de água induzidas pela injeção ip de pilocarpina (1 mg/kg de peso corporal). A salivação foi medida em ratos anestesiados com ketamina utilizando-se bolas de algodão previamente pesadas colocadas na cavidade oral durante 7 minutos. O volume da água ingerida foi medido durante 1 h após a injeção ip de pilocarpina.
The study of sialagogue substances is of clinical interest because of the usefulness they have in patients with xerostomia. Among these, cholinergic agonists stand out, with pilocarpine being one of the most important. Peripherally injected pilocarpine induces salivation and water ingestion. The intracerebroventricular (icv) injection of muscarinic antagonists showed that the salivation produced by pilocarpine injected intraperitoneally (ip) depends on the activation of central muscarinic M3 receptors, while M1 and M2 receptors would participate in water ingestion and pressor response, however, the responsible brain areas for these responses still need to be studied. Tests combining ip pilocarpine with injection of specific antagonists of different types of muscarinic receptors in the medial septal area (ASM) of the rat brain are important to define the participation of ASM in the responses produced by ip pilocarpine and also to characterize the receptors specific muscarinics involved in these responses. Thus, the aim of the project was to investigate the effects of injecting specific antagonists of M1, M2, M3 and M4 receptors in ASM on salivation and water ingestion produced by ip-injected pilocarpine. Holtzman rats were used, with stainless steel cannulas implanted in the ASM. We investigated the effects of previous ASM injections of 4-DAMP (M1/M3 antagonist), pirenzepine (M1 muscarinic antagonist), methoctramine (M2/M4 muscarinic antagonist) and tropicamide (M4 muscarinic antagonist) on induced salivation and water intake. by ip injection of pilocarpine (1 mg/kg body weight). Salivation was measured in ketamine-anesthetized rats using previously weighed cotton balls placed in the oral cavity for 7 minutes. The volume of water ingested was measured for 1 h after the ip injection of pilocarpine.
The study of sialagogue substances is of clinical interest because of the usefulness they have in patients with xerostomia. Among these, cholinergic agonists stand out, with pilocarpine being one of the most important. Peripherally injected pilocarpine induces salivation and water ingestion. The intracerebroventricular (icv) injection of muscarinic antagonists showed that the salivation produced by pilocarpine injected intraperitoneally (ip) depends on the activation of central muscarinic M3 receptors, while M1 and M2 receptors would participate in water ingestion and pressor response, however, the responsible brain areas for these responses still need to be studied. Tests combining ip pilocarpine with injection of specific antagonists of different types of muscarinic receptors in the medial septal area (ASM) of the rat brain are important to define the participation of ASM in the responses produced by ip pilocarpine and also to characterize the receptors specific muscarinics involved in these responses. Thus, the aim of the project was to investigate the effects of injecting specific antagonists of M1, M2, M3 and M4 receptors in ASM on salivation and water ingestion produced by ip-injected pilocarpine. Holtzman rats were used, with stainless steel cannulas implanted in the ASM. We investigated the effects of previous ASM injections of 4-DAMP (M1/M3 antagonist), pirenzepine (M1 muscarinic antagonist), methoctramine (M2/M4 muscarinic antagonist) and tropicamide (M4 muscarinic antagonist) on induced salivation and water intake. by ip injection of pilocarpine (1 mg/kg body weight). Salivation was measured in ketamine-anesthetized rats using previously weighed cotton balls placed in the oral cavity for 7 minutes. The volume of water ingested was measured for 1 h after the ip injection of pilocarpine.
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Palavras-chave
Saliva, Glândulas salivares, Receptores muscarínicos, Saliva, Salivary glands, Receptors, muscarinic