Anxiolytic effect of a CRH receptor antagonist in the dorsal periaqueductal gray.
Corticotropin-releasing hormone (CRH) is anxiogenic when microinjected into the dorsal periaqueductal gray (DPAG). Microinjection of alpha-helical-CRH9-41 (0.5 microgram), a CRH receptor antagonist, however, failed to change anxiety levels. The objective of this study was to verify if this compound has any effect in the anxiogenic behavior of rats submitted to 4 hr of restraint stress 24 hr before the test in an elevated plus maze. Results showed that stressed rats had a decreased exploration of open arms without changing the number of enclosed arm entries. The stress effect was reversed by intra-DPAG injection of alpha-helical-CRH9-41 (0.5 microgram). These results suggest that the anxiogenic behavior of rats previously stressed by forced immobilization might involve facilitation of CRH-mediated neurotransmission in the DPAG.
Martins
A P
AP
Department of Pharmacology, FMRP, SP, Brazil.
Marras
R A
RA
Guimarães
F S
FS
D000818:Animals; D001008:Anxiety Disorders / Q000378:metabolism*; D001522:Behavior, Animal / Q000187:drug effects; D002552:Cerebral Ventricles / Q000187:drug effects*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D005106:Exploratory Behavior / Q000187:drug effects; D007276:Injections, Intraventricular; D018782:Maze Learning / Q000187:drug effects; D008845:Microinjections; D009431:Neural Conduction / Q000187:drug effects; D010446:Peptide Fragments / Q000187:drug effects / Q000494:pharmacology*; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors*
D010446:Peptide Fragments; D018019:Receptors, Corticotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; C045089:corticotropin releasing hormone (9-41)