Participation of the medial septal area in the pressor response produced by intravenous injection of pilocarpine

• Grant number: 21/13854-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2022
• End date: December 31, 2022
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: José Vanderlei Menani
• Grantee: Lineker Vieira Pio
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The study of sialagogue substances is of clinical interest because of their use in patients with xerostomia. Among them cholinergic agonists are particularly important and in this pharmacological class pilocarpine is one of the most important. Pilocarpine injected peripherally induces salivation, water intake and pressor response. 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 participates in water intake and pressor responses, however, it is not clear yet which are the brain areas involved in these responses. The injection of 4-DAMP (M1/M3 antagonist) into the medial septal area (MSA) reduced salivation induced by pilocarpine ip, whereas the injection of metoctramine (M2/M4 antagonist) into the MSA reduced pilocarpine induced water intake. The importance of the MSA and which type of muscarinic receptor subtype in the MSA is involved in the pressor response to intravenous (iv) pilocarpine was not investigated yet. Thus, the objective of the present project is to investigate the effects of the injection of specific M1, M2/M4, M1/M3 and M4 receptor antagonists into the MSA in the pressor response produced by pilocarpine injected iv. It will be used male Holtzman rats with stainless steel cannulas implanted in the MSA and arterial and venous cannulas implanted for recording arterial pressure and iv injection, respectively. It will be tested the effects of previous injections of pirenzepine (M1 muscarinic antagonist), metoctramine (M2/M4 muscarinic antagonist), 4-DAMP (M1/M3 muscarinic antagonista) and tropicamide (M4 muscarinic antagonist) into the MSA in the pressor response produced by iv injection of pilocarpine (0.5 mg/kg of body weight). Arterial pressure and heart rate will be recorded in conscious freely moving rats, connecting the arterial cannula to a pressure transducer coupled to a computer recording system. (AU)