de Abreu A R, Abreu A R, Santos L T, de Souza A A, da Silva L G, Chianca D A, de Menezes R C
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil.
Department of Basic Health Sciences, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil.
Neuroscience. 2015 Jan 22;284:737-750. doi: 10.1016/j.neuroscience.2014.10.055. Epub 2014 Nov 4.
There is ample evidence that both lateral/dorsolateral periaqueductal gray (l/dlPAG) and basolateral amygdala (BLA) are essential for the regulation of the autonomic responses evoked during innate reactions to threatening stimuli. However, it is not well established to what extent the BLA regulates the upstream functional connection from the l/dlPAG. Here we evaluated the role of the BLA and its glutamatergic receptors in the cardiovascular responses induced by l/dlPAG stimulation in rats. We examined the influence of acute inhibition of the BLA, unilaterally, by injecting muscimol on the cardiovascular responses evoked by the injection of N-methyl D-aspartate (NMDA) into the l/dlPAG. We also evaluated the role of BLA ionotropic glutamate receptors in these responses by injecting antagonists of NMDA and AMPA/kainate receptor subtypes into the BLA. Our results show that the microinjection of NMDA in the BLA increased the mean arterial pressure (MAP) and heart rate (HR). Injection of NMDA into the l/dlPAG caused similar increases in these variables, which was prevented by the prior injection of muscimol, a GABAA agonist, into the BLA. Moreover, injection of glutamatergic antagonists (2-amino-5-phosphonopentanoate (AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)) into the BLA reduced the increase in MAP and HR induced by l/dlPAG activation. Finally, the inhibition of the central amygdala neurons failed to reduce the cardiovascular changes induced by l/dlPAG activation. These results indicate that physiological responses elicited by l/dlPAG activation require the neuronal activity in the BLA. This ascending excitatory pathway from the l/dlPAG to the BLA might ensure the expression of the autonomic component of the defense reaction.
有充分证据表明，外侧/背外侧导水管周围灰质（l/dlPAG）和基底外侧杏仁核（BLA）对于调节在对威胁性刺激的先天反应中诱发的自主反应至关重要。然而，BLA在多大程度上调节来自l/dlPAG的上游功能连接尚不清楚。在此，我们评估了BLA及其谷氨酸能受体在大鼠l/dlPAG刺激诱导的心血管反应中的作用。我们通过向BLA单侧注射蝇蕈醇来急性抑制BLA，研究其对向l/dlPAG注射N-甲基-D-天冬氨酸（NMDA）所诱发的心血管反应的影响。我们还通过向BLA注射NMDA和AMPA/海人藻酸受体亚型的拮抗剂，评估了BLA离子型谷氨酸受体在这些反应中的作用。我们的结果表明，向BLA微量注射NMDA可增加平均动脉压（MAP）和心率（HR）。向l/dlPAG注射NMDA也会使这些变量出现类似增加，而预先向BLA注射GABAA激动剂蝇蕈醇可防止这种情况。此外，向BLA注射谷氨酸能拮抗剂（2-氨基-5-磷酸戊酸（AP5）和6-氰基-7-硝基喹喔啉-2,3-二酮（CNQX））可减少l/dlPAG激活所诱导的MAP和HR增加。最后，抑制中央杏仁核神经元未能减少l/dlPAG激活所诱导的心血管变化。这些结果表明，l/dlPAG激活引发的生理反应需要BLA中的神经元活动。这条从l/dlPAG到BLA的上行兴奋性通路可能确保防御反应自主成分的表达。
