title: NMDA receptors in the lateral hypothalamus have an inhibitory influence on the tachycardiac response to acute restraint stress in rats.
abstract: The aim of the present study was to investigate the role of the lateral hypothalamus (LH) and its local glutamatergic neurotransmission in the cardiovascular adjustments observed when rats are submitted to acute restraint stress. Bilateral microinjection of the nonspecific synaptic inhibitor CoCl2 (0.1 nmol in 100 nL) into the LH enhanced the heart rate (HR) increase evoked by restraint stress without affecting the blood pressure increase. Local microinjection of the selective N-methyl-d-aspartate (NMDA) glutamate receptor antagonist LY235959 (2 nmol in 100 nL) into the LH caused effects that were similar to those of CoCl2 . No changes were observed in the restraint-related cardiovascular response after a local microinjection of the selective non-NMDA glutamatergic receptor antagonist NBQX (2 nmol in 100 nL) into the LH. Intravenous administration of the muscarinic cholinergic receptor antagonist homatropine methyl bromide (0.2 mg/kg), a quaternary ammonium drug that does not cross the blood-brain barrier, abolished the changes in cardiovascular responses to restraint stress following LH treatment with LY235959. In summary, our findings show that the LH plays an inhibitory role on the HR increase evoked by restraint stress. Present results also indicate that local NMDA glutamate receptors, through facilitation of cardiac parasympathetic activity, mediate the LH inhibitory influence on the cardiac response to acute restraint stress.
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Milena V
authors.initials: MV
authors.lastname: Deolindo
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Reis
authors.forename: Carlos C
authors.initials: CC
authors.lastname: Crestani
authors.forename: Rodrigo F
authors.initials: RF
authors.lastname: Tavares
authors.forename: Leonardo B M
authors.initials: LB
authors.lastname: Resstel
authors.forename: Fernando M A
authors.initials: FM
authors.lastname: Corrêa
mesh_terms: D000818:Animals; D003035:Cobalt / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D007026:Hypothalamic Area, Lateral / Q000187:drug effects / Q000502:physiology*; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D051379:Mice; D009433:Neural Inhibition / Q000187:drug effects; D010276:Parasympatholytics / Q000494:pharmacology; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000187:drug effects; D014326:Tropanes / Q000494:pharmacology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D007546:Isoquinolines; D010276:Parasympatholytics; D016194:Receptors, N-Methyl-D-Aspartate; D014326:Tropanes; D003035:Cobalt; C056244:homatropine methylbromide; C088643:LY 235959; C018021:cobaltous chloride
keywords: NMDA receptors; autonomic activity; cardiovascular response; hypothalamus; stress