Department of Pharmacology School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
J Neurosci Res. 2012 Nov;90(11):2193-200. doi: 10.1002/jnr.23094. Epub 2012 Jun 20.
The periaqueductal gray area (PAG) is a mesencephalic area involved in cardiovascular modulation. Glutamate (L-Glu) is an abundant excitatory amino acid in the central nervous system (CNS) and is present in the rat PAG. Moreover, data in the literature indicate its involvement in central blood pressure control. Here we report on the cardiovascular effects caused by microinjection of L-Glu into the dorsomedial PAG (dmPAG) of rats and the glutamatergic receptors as well as the peripheral mechanism involved in their mediation. The microinjection of L-Glu into the dmPAG of unanesthetized rats evoked dose-related pressor and bradycardiac responses. The cardiovascular response was significantly reduced by pretreatment of the dmPAG with a glutamatergic M-methyl-D-aspartate (NMDA) receptor antagonist (LY235959) and was not affected by pretreatment with a non-NMDA receptor antagonist (NBQX), suggesting a mediation of that response by the activation of NMDA receptors. Furthermore, the pressor response was blocked by pretreatment with the ganglion blocker pentolinium (5 mg/kg, intravenously), suggesting an involvement of the sympathetic nervous system in this response. Our results indicate that the microinjection of L-Glu into the dmPAG causes sympathetic-mediated pressor responses in unanesthetized rats, which are mediated by glutamatergic NMDA receptors in the dmPAG.
导水管周围灰质（PAG）是参与心血管调节的中脑区域。谷氨酸（L-Glu）是中枢神经系统（CNS）中丰富的兴奋性氨基酸，存在于大鼠的 PAG 中。此外，文献中的数据表明它参与了中枢血压控制。在这里，我们报告了将 L-Glu 微注射到大鼠背内侧 PAG（dmPAG）中引起的心血管效应，以及涉及介导这些效应的谷氨酸能受体和外周机制。将 L-Glu 微注射到未麻醉大鼠的 dmPAG 中会引起剂量相关的升压和心动过缓反应。dmPAG 预先用谷氨酸能 N-甲基-D-天冬氨酸（NMDA）受体拮抗剂（LY235959）预处理可显著减少心血管反应，而用非 NMDA 受体拮抗剂（NBQX）预处理则不会影响该反应，表明该反应由 NMDA 受体的激活介导。此外，预先用神经节阻滞剂戊烷脒（5mg/kg，静脉内）预处理可阻断升压反应，表明交感神经系统参与了该反应。我们的结果表明，将 L-Glu 微注射到 dmPAG 中会导致未麻醉大鼠的交感神经介导的升压反应，该反应由 dmPAG 中的谷氨酸能 NMDA 受体介导。
