Contribution of excitatory amino acid receptors in the dorsomedial hypothalamus and periaqueductal gray to the asymmetry and lateralization in the cardiovascular responses to stress in rats

Xavier, Carlos Henrique; Vaz, Gisele Cristiane; Lima, André Maia; Ianzer, Danielle; Nalivaiko, Eugene; Fontes, M.A.P.

doi:10.1016/j.autneu.2011.05.058

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“…In the present study, we compared the cardiovascular responses evoked by activation and blockade of EAA receptors in the right and left sides of the DMH and PAG. A portion of our results have been presented in abstract form [30] .…”

Section: Introductionmentioning

confidence: 99%

Excitatory Amino Acid Receptors Mediate Asymmetry and Lateralization in the Descending Cardiovascular Pathways from the Dorsomedial Hypothalamus

et al. 2014

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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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Section: Introductionmentioning

confidence: 99%