Corticotropin-releasing factor in the dorsal raphe elicits temporally distinct serotonergic responses in the limbic system in relation to fear behavior.
The neurotransmitters serotonin and corticotrophin-releasing factor are thought to play an important role in fear and anxiety behaviors. This study aimed to determine the relationship between corticotrophin-releasing factor-evoked changes in serotonin levels within discrete regions of the limbic system and the expression of fear behavior in rats. The effects of corticotrophin-releasing factor administration to the serotonin cell body regions of the dorsal raphe nucleus on fear behavior, behavioral activity, and extracellular serotonin levels were assessed in freely moving rats with microdialysis probes implanted into the central nucleus of the amygdala and the medial prefrontal cortex. Infusion of corticotrophin-releasing factor (0.5 microg) into the dorsal raphe rapidly induced freezing behavior, which was positively correlated with an immediate increase in serotonin release in the central nucleus of the amygdala. In contrast, cessation of freezing behavior correlated with a delayed and prolonged increase in serotonin release within the medial prefrontal cortex. Our findings suggest that corticotrophin-releasing factor-induced freezing behavior is associated with regionally and temporally distinct serotonergic responses in the limbic system that may reflect differing roles for these regions in the expression of fear/anxiety behavior.
Forster
G L
GL
Division of Basic Biomedical Sciences, Neuroscience Group, Sanford School of Medicine at the University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA. Electronic address: gforster@usd.edu.
Feng
N
N
Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
Watt
M J
MJ
Division of Basic Biomedical Sciences, Neuroscience Group, Sanford School of Medicine at the University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA; Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
Korzan
W J
WJ
Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA; Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA.
Mouw
N J
NJ
Division of Basic Biomedical Sciences, Neuroscience Group, Sanford School of Medicine at the University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA; Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
Summers
C H
CH
Division of Basic Biomedical Sciences, Neuroscience Group, Sanford School of Medicine at the University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA; Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
Renner
K J
KJ
Division of Basic Biomedical Sciences, Neuroscience Group, Sanford School of Medicine at the University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA; Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage*; D005239:Fear / Q000502:physiology*; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects; D008032:Limbic System / Q000378:metabolism*; D008297:Male; D017551:Microdialysis / Q000379:methods; D011903:Raphe Nuclei / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D003346:Corticotropin-Releasing Hormone