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Microinjection of a cannabinoid receptor antagonist into the NTS increases baroreflex duration in dogs. Am J Physiol Heart Circ Physiol 2003 May;284(5):H1570-6

Date

01/11/2003

Pubmed ID

12521935

DOI

10.1152/ajpheart.00772.2002

Scopus ID

2-s2.0-0037405166 (requires institutional sign-in at Scopus site)   31 Citations

Abstract

Baroreceptor afferent fibers synapse in the nucleus tractus solitarius (NTS) of the medulla. Neuronal cannabinoid (CB)(1) receptors are expressed in the NTS and central administration of CB(1) receptor agonists affect blood pressure (BP) and heart rate. In addition, there is evidence that endocannabinoids are produced in the brain stem. This study examined whether changes in CB(1) receptor activity in the NTS modulated the baroreceptor reflex, contributing to changes seen in BP and heart rate. Baroreflexes were evoked in anesthetized dogs by pressure ramp stimulations of the isolated carotid sinus before and after microinjection of CB(1) receptor agonist WIN-55212-2 (1.25-1.50 pmol) or antagonist SR-141716 (2.5-3.0 pmol) into cardiovascular regions of the NTS. Microinjection of the SR-141716 did not affect baseline BP or baroreflex sensitivity. However, SR-141716 significantly prolonged the time needed to return to the baseline level of BP after the pressure ramp. Microinjection of WIN-55212-2 had no effect on the baroreflex. These data suggest that endocannabinoids can modulate the excitability of NTS neurons involved in the baroreceptor reflex, leading to modulation of baroreflex regulation.

Author List

Rademacher DJ, Patel S, Hopp FA, Dean C, Hillard CJ, Seagard JL

Author

Cecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Analgesics
Animals
Baroreflex
Benzoxazines
Blood Pressure
Cannabinoid Receptor Modulators
Dogs
Microinjections
Morpholines
Naphthalenes
Piperidines
Pyrazoles
Receptors, Cannabinoid
Receptors, Drug
Solitary Nucleus
Sympathetic Nervous System