The role of 5-HT1A receptors in the behavioral responses associated with innate fear.
Fear is a response induced by threatening stimuli and represents an important adaptive system. The serotonin (5-HT) system has been shown to be involved in the modulation of fear responses and anxiety disorders. In preclinical studies, it has been demonstrated that R (+)-8-hydroxy-dipropylaminotetralin (8-OHDPAT), a 5-HT1A agonist, has anxiolytic properties. However, 8-OHDPATs potential role in unconditioned fear has yet to be elucidated. The current study was designed to investigate the effects of 8-OHDPAT on behavioral and HPA axis function in response to an innate fear-inducing stimulus. Pretreatment with 8-OHDPAT resulted in a significant decrease in freezing grooming, and climbing and caused a significant increase in approach after exposure to an extract from fox feces, 2,5-dihyrdo-2,4,5-trimethylthiazoline (TMT), an unconditioned fear-inducing stimulus. Furthermore, 8-OHDPAT pretreatment also resulted in a significant decrease in blood corticosterone levels, a marker of HPA activation. Taken together, these results suggest an additional anxyolitic-like effect of 8-OHDPAT in innate fear paradigms.
University of Massachusetts Medical School, Department of Psychiatry, Center for Comparative NeuroImaging, 55 Lake Avenue North, Worcester, MA 01655, USA.
Jessica
J
Shields
Jean A
JA
King
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005239:Fear / Q000187:drug effects; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013844:Thiazoles / Q000008:administration & dosage
C411827:2,5-dihydro-2,4,5-trimethylthiazoline; D017366:Serotonin Receptor Agonists; D013844:Thiazoles; D044282:Receptor, Serotonin, 5-HT1A; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D003345:Corticosterone