The role of 5-HT1A receptors in the behavioral responses associated with innate fear
Department of Psychiatry
Medical Subject Headings
8-Hydroxy-2-(di-n-propylamino)tetralin; Analysis of Variance; Animals; Behavior, Animal; Conditioning (Psychology); Corticosterone; Dose-Response Relationship, Drug; *Fear; Freezing Reaction, Cataleptic; Male; Motor Activity; Rats; Rats, Sprague-Dawley; Receptor, Serotonin, 5-HT1A; Serotonin Agonists; Thiazoles
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.
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Citation: Behav Neurosci. 2008 Jun;122(3):611-7. Link to article on publisher's site