Resstel L B M, Corrêa F M A
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Eur J Neurosci. 2005 May;21(9):2513-20. doi: 10.1111/j.1460-9568.2005.04078.x.
The ventral medial prefrontal cortex (vMPFC) is involved in central cardiovascular control. In the present study, we studied the cardiovascular effects of injections of L-glutamate into the vMPFC of unanaesthetized rats and the mechanisms of these effects. Male Wistar rats were used and L-glutamate was microinjected in the vMPFC in a final volume of 200 nL. Microinjections of L-glutamate (9, 27, 81, 150 or 300 nmol) caused long-lasting, dose-related pressor and tachycardic responses in unanaesthetized rats. No differences were observed among cardiovascular responses when L-glutamate was injected into the three sub-areas that comprise the vMPFC, namely the prelimbic, the infralimbic and the dorsal peduncular cortices. No responses were observed when the dose of 81 nmol of L-glutamate was microinjected into surrounding structures such as the cingulate cortex area 1, the corpus callosum and the tenia tecta, indicating a predominant action on the vMPFC. The cardiovascular response to L-glutamate into the vMPFC was blocked by intravenous pretreatment with the ganglion blocker pentolinium (10 mg/kg, i.v.) or the beta1-adrenoceptor antagonist atenolol (1.5 mg/kg, i.v.), supporting the involvement of the cardiac sympathetic nervous system in the response to L-glutamate. Pretreatment with the muscarinic antagonist homatropine methyl bromide (1 mg/kg, i.v.) reduced the latency to the onset of the pressor and tachycardic responses to L-glutamate injected into the vMPFC without significant effects on response duration or maximum effect. We conclude that stimulation of the vMPFC with L-glutamate caused pressor and tachycardic responses in unanaesthetized rats, responses which were dependent on cardiac sympathetic nerve activation and were potentiated by blockade of peripheral muscarinic receptors.
腹内侧前额叶皮质（vMPFC）参与中枢心血管控制。在本研究中，我们研究了向未麻醉大鼠的vMPFC注射L-谷氨酸的心血管效应及其作用机制。使用雄性Wistar大鼠，将L-谷氨酸以终体积200 nL微量注射到vMPFC中。向未麻醉大鼠微量注射L-谷氨酸（9、27、81、150或300 nmol）可引起持久的、剂量相关的升压和心动过速反应。当将L-谷氨酸注射到构成vMPFC的三个子区域，即前边缘区、边缘下区和背侧脚状核皮质时，心血管反应没有差异。当将81 nmol的L-谷氨酸微量注射到扣带回皮质1区、胼胝体和 tenia tecta等周围结构时，未观察到反应，这表明对vMPFC有主要作用。静脉注射神经节阻滞剂喷托铵（10 mg/kg，静脉注射）或β1肾上腺素能受体拮抗剂阿替洛尔（1.5 mg/kg，静脉注射）预处理可阻断向vMPFC注射L-谷氨酸引起的心血管反应，这支持心脏交感神经系统参与对L-谷氨酸的反应。用毒蕈碱拮抗剂甲基溴化后马托品（1 mg/kg，静脉注射）预处理可缩短向vMPFC注射L-谷氨酸引起的升压和心动过速反应的起始潜伏期，而对反应持续时间或最大效应无显著影响。我们得出结论，用L-谷氨酸刺激vMPFC会在未麻醉大鼠中引起升压和心动过速反应，这些反应依赖于心脏交感神经激活，并通过阻断外周毒蕈碱受体而增强。
