Xavier Carlos Henrique, Ianzer Danielle, Lima Augusto Martins, Marins Fernanda Ribeiro, Pedrino Gustavo Rodrigues, Vaz Gisele, Menezes Gustavo Batista, Nalivaiko Eugene, Fontes Marco Antônio Peliky
Laboratório de Fisiologia e Terapêutica Cardiovascular, Departamento Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, GO, Brazil; Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
PLoS One. 2014 Nov 14;9(11):e112412. doi: 10.1371/journal.pone.0112412. eCollection 2014.
The dorsomedial hypothalamus (DMH) and lateral/dorsolateral periaqueductal gray (PAG) are anatomically and functionally connected. Both the DMH and PAG depend on glutamatergic inputs for activation. We recently reported that removal of GABA-ergic tone in the unilateral DMH produces: asymmetry, that is, a right- (R-) sided predominance in cardiac chronotropism, and lateralization, that is, a greater increase in ipsilateral renal sympathetic activity (RSNA). In the current study, we investigated whether excitatory amino acid (EAA) receptors in the DMH-PAG pathway contribute to the functional interhemispheric difference. In urethane (1.2 to 1.4 g/kg, i.p.) anesthetized rats, we observed that: (i) nanoinjections of N-methyl D-aspartate (NMDA 100 pmol/100 nl) into the unilateral DMH produced the same right-sided predominance in the control of cardiac chronotropy, (ii) nanoinjections of NMDA into the ipsilateral DMH or PAG evoked lateralized RSNA responses, and (iii) blockade of EAA receptors in the unilateral DMH attenuated the cardiovascular responses evoked by injection of NMDA into either the R- or left- (L-) PAG. In awake rats, nanoinjection of kynurenic acid (1 nmol/100 nL) into the L-DMH or R- or L-PAG attenuated the tachycardia evoked by air stress. However, the magnitude of stress-evoked tachycardia was smallest when the EAA receptors of the R-DMH were blocked. We conclude that EAA receptors contribute to the right-sided predominance in cardiac chronotropism. This interhemispheric difference that involves EAA receptors was observed in the DMH but not in the PAG.
背内侧下丘脑（DMH）与外侧/背外侧导水管周围灰质（PAG）在解剖学和功能上相互连接。DMH和PAG的激活均依赖于谷氨酸能输入。我们最近报道，单侧DMH中GABA能张力的去除会产生：不对称性，即心脏变时性中右侧（R侧）占优势；以及偏侧化，即同侧肾交感神经活动（RSNA）有更大增加。在本研究中，我们调查了DMH-PAG通路中的兴奋性氨基酸（EAA）受体是否导致了功能性半球间差异。在氨基甲酸乙酯（1.2至1.4 g/kg，腹腔注射）麻醉的大鼠中，我们观察到：（i）向单侧DMH微量注射N-甲基-D-天冬氨酸（NMDA，100 pmol/100 nl）在心脏变时性控制中产生相同的右侧优势；（ii）向同侧DMH或PAG微量注射NMDA诱发了偏侧化的RSNA反应；（iii）单侧DMH中EAA受体的阻断减弱了向R侧或左侧（L侧）PAG注射NMDA所诱发的心血管反应。在清醒大鼠中，向L-DMH或R侧或L侧PAG微量注射犬尿氨酸（1 nmol/100 nL）减弱了空气应激诱发的心动过速。然而，当R-DMH的EAA受体被阻断时，应激诱发的心动过速幅度最小。我们得出结论，EAA受体促成了心脏变时性中的右侧优势。这种涉及EAA受体的半球间差异在DMH中观察到，而在PAG中未观察到。
