Excitatory amino acid receptors mediate asymmetry and lateralization in the descending cardiovascular pathways from the dorsomedial hypothalamus
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2014-11
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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.
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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. Excitatory amino acid receptors mediate asymmetry and lateralization in the descending cardiovascular pathways from the dorsomedial hypothalamus. PLoS One, San Francisco, v. 9, e112412, Nov. 2014.