Abstract
Corticotropin-releasing factor (CRF) is the major physiological regulator of the hypothalamic-pituitary-adrenal (HPA) axis and serves to coordinate the mammalian endocrine, autonomic, and behavioral responses to stress. Considerable literature from clinical and preclinical data suggests that hypersecretion of hypothalamic and/or extrahypothalamic CRF systems is a major factor in the pathogenesis of affective and anxiety disorders. Based on this premise, a CRF1 receptor antagonist has been hypothesized to possess anxiolytic and/or antidepressant properties. In this study, an acute dose of the lipophilic CRF1 receptor antagonist 3-[6-(dimethylamino)-4-methyl-pyrid-3-yl]-2,5-dimethyl-N,N-dipropyl-pyrazolo[2,3-a]pyrimidin-7-amine (R121919), administered i.v. to rats with surgically implanted jugular cannula 60 min before a 5-min restraint stress, dose dependently attenuated peak plasma adrenocorticopin hormone (ACTH) and corticosterone concentrations by 91 and 75%, respectively. In a second study, acute administration of R121919 reduced measures of anxiety in a rodent defensive withdrawal paradigm. R121919 dose dependently decreased latency to exit the tube, and total time spent in the tube 60 min after a single subcutaneous administration. In addition, the ACTH and corticosterone response to novelty was decreased by 82 and 97%, respectively, at the 10-mg/kg dose of R121919. In another study, this dose was associated with approximately an 85% occupancy of the CRF1 receptor in the cortex measured 75-min postsubcutaneous injection. These data confirm that R121919 acts as a CRF1 receptor antagonist in vivo, attenuates HPA axis responsivity, and possesses anxiolytic properties.
Footnotes
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This study was supported by National Institute of Mental Health MH-42008 and the Conte Center for the Neurobiology of Mental Disorders.
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DOI: 10.1124/jpet.102.042788
- Abbreviations:
- CRF
- corticotropin-releasing factor
- HPA
- hypothalamic-pituitary-adrenal
- ACTH
- adrenocorticopin hormone
- CORT
- corticosterone
- ANOVA
- analysis of variance
- SNK
- Student-Newman-Keuls
- Received August 6, 2002.
- Accepted October 8, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
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