Involvement of ventral hippocampus glutamatergic and nitrergic neurotransmission on cardiovascular system modulation in rats

• Grant number: 10/04086-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2010
• End date: June 30, 2011
• Field of knowledge: Biological Sciences - Pharmacology - Autonomic Pharmacology
• Principal Investigator: Leonardo Resstel Barbosa Moraes
• Grantee: Cibele Santini de Oliveira
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The hippocampus is a brain structure which is part of the limbic system involved in emotional processes, learning and memory. In rats electrical stimulation of this area evoke defensive reactions, visceral and autonomic changes such as decrease or increase of heart rate and blood pressure, depending on the anesthetic used and the sub-region stimulated.Glutamate is one of the main neurotransmitters of the central nervous system. The administration of glutamate in the dorsal or ventral hippocampus evokes decrease in heart rate, blood pressure and respiratory rate. Furthermore, the hippocampus is able to modulate cardiovascular and behavioral responses during aversive situations. Under stress there is an increased release of glutamate in the hippocampus, suggesting that this area has glutamatergic system activated during defensive reaction.It has been reported that activation of NMDA receptors by administration of glutamate in regions of the central nervous system of rats increases blood pressure and heart rate via activation of nitric oxide synthase (NOS). In the hippocampus, the activation of NMDA receptors also is involved with increase of NO levels.The known about the involvement of the glutamatergic and nitrergic systems into the ventral hippocampus on the control of cardiovascular activity is poor. Therefore, this project's hypothesis is that glutamatergic and nitrergic systems into the ventral hippocampus are involved with cardiovascular system modulation in rats. The objective of this study is to assess the cardiovascular responses caused by the administration of different doses of glutamate in the ventral hippocampus of anesthetized rats, the type of glutamatergic receptor involved in these responses and the interaction between glutamatergic and nitrergic systems present in this area.