Role of 5-HT1A receptors in the lower brainstem on the cardiovascular response to dorsomedial hypothalamus activation

Jouji Horiuchi*, Lachlan M. McDowall, Roger A L Dampney

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

The dorsomedial hypothalamus (DMH) is an essential brain region for the integration of the physiological response to psychological stressors. The cardiovascular components of the response include increases in blood pressure, heart rate and the activity of sympathetic nerves to the kidney, skin, brown adipose tissue, and heart. Neurons in the rostral ventrolateral medulla (RVLM) and in the region of the medullary raphe are important components of the descending pathways that mediate the cardiovascular response to the DMH activation. Activation of 5-hydroxytryptamine 1A (5-HT1A) receptors in the brain leads to a suppression of the cardiac and sympathetic vasomotor components of the DMH-evoked response and of the response to acute psychological stress. In this study we showed that intracisternal injection of a low dose (1 μg/kg) of the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), significantly reduced the increases in heart rate and renal sympathetic nerve activity evoked by disinhibition of the DMH, but had no effect on these responses when injected intravenously. Subsequent intracisternal administration of the 5-HT1A receptor antagonist WAY-100635 restored the DMH-evoked cardiovascular responses to levels observed before 8-OH-DPAT administration. Bilateral microinjections of 8-OH-DPAT (200pmol on each side) into the RVLM, however, did not significantly affect the cardiovascular response to disinhibition of the DMH. These observations demonstrate that activation of 5-HT1A receptors within the lower brainstem, but not in the RVLM, can powerfully suppress the cardiovascular response evoked from the DMH.

Original languageEnglish
Pages (from-to)71-76
Number of pages6
JournalAutonomic Neuroscience: Basic and Clinical
Volume142
Issue number1-2
DOIs
Publication statusPublished - 3 Nov 2008
Externally publishedYes

Keywords

  • Rostral ventrolateral medulla
  • Serotonin
  • Stress
  • Sympathetic activity

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