Cardiovascular responses to activation of metabotropic glutamate receptors in the nTS of the rat

Eddy Viard, Hreday N. Sapru

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Although several agonists and antagonists for different subtypes of metabotropic glutamate receptors (mGLURs) have become available in recent years, detailed information regarding their selectivity is not complete in the in vivo animal models. The purpose of the present investigation was to study the cardiovascular effects of microinjections of some of these mGLUR agonists and antagonists into the nucleus tractus solitarius (nTS). Microinjections (100 nl) of EC50 concentrations of 3,5-DHPG (0.005 mM; mGLUR1 agonist), APDC (17.3 mM; mGLUR2/3 agonist), PPG (11.7 mM; mGLUR8 agonist) and L-AP4 (1 mM; mGLUR4 agonist) into the nucleus tractus solitarius of urethane-anesthetized male Wistar rats elicited depressor and bradycardic responses which may be mediated by pre- and/or postsynaptic mechanisms. The blocking effect of mGLUR antagonists used here was not specific for any one type of glutamate receptors (GLURs). For example, AIDA (50 mM; mGLUR1 antagonist) blocked the effects of EC50 concentrations of 3,5-DHPG, and PPG. LY341495 (135 mM; mGLUR2/3 antagonist) blocked all of the mGLURs and ionotropic GLURs. EGLU, APICA and MCCG (250 mM each; mGLUR2/3 antagonists) blocked the effects of APDC, NMDA and AMPA. CPPG (80 mM) and MSOP (125 mM), mGLUR4 antagonists, blocked the effects of 3,5-DHPG, PPG and L-AP4. D-AP7 (NMDA receptor antagonist) and NBQX (a non-NMDA receptor antagonist) did not alter the responses of any of the mGLUR agonists. The data presented may be useful in assessing the role of metabotropic and ionotropic GLURs in mediating different cardiovascular reflexes.

Original languageEnglish (US)
Pages (from-to)308-321
Number of pages14
JournalBrain research
Issue number2
StatePublished - Oct 18 2002

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


  • Blood pressure
  • Bradycardia
  • Depressor responses
  • Glutamate
  • Heart rate

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