None of the authors report conflicts of interest related to the submitted manuscript.
Klein Award Winner
ELEVATED tph2 mRNA EXPRESSION IN A RAT MODEL OF CHRONIC ANXIETY
Article first published online: 17 APR 2012
© 2012 Wiley Periodicals, Inc.
Depression and Anxiety
Volume 29, Issue 4, pages 307–319, April 2012
How to Cite
Donner, N. C., Johnson, P. L., Fitz, S. D., Kellen, K. E., Shekhar, A. and Lowry, C. A. (2012), ELEVATED tph2 mRNA EXPRESSION IN A RAT MODEL OF CHRONIC ANXIETY. Depress. Anxiety, 29: 307–319. doi: 10.1002/da.21925
- Issue published online: 17 APR 2012
- Article first published online: 17 APR 2012
- University of Colorado Boulder and Anantha Shekhar at the Indiana University School of Medicine. Grant Number: NIH R01MH065702–08
- anxiety/anxiety disorders;
- biological markers;
- mood disorders;
- panic attacks/agoraphobia;
Allelic variations in TPH2, the gene encoding tryptophan hydroxylase 2, the rate-limiting enzyme for brain serotonin (5-HT) biosynthesis, may be genetic predictors of panic disorder and panic responses to panicogenic challenges in healthy volunteers. To test the hypothesis that tph2 mRNA is altered in chronic anxiety states, we measured tph2 expression in an established rat model of panic disorder.
We implanted 16 adult, male rats with bilateral guide cannulae and then primed them with daily injections of the corticotropin-releasing factor (CRF) receptor agonist, urocortin 1 (UCN1, 6 fmoles/100 nl per side, n = 8) or vehicle (n = 8) into the basolateral amygdaloid complex (BL) for 5 consecutive days. Anxiety-like behavior was assessed, 24 hr prior to and 48 hr following priming, in the social interaction (SI) test. A third group (n = 7) served as undisturbed home cage controls. All rats were killed 3 days after the last intra-BL injection to analyze tph2 and slc6a4 (gene encoding the serotonin transporter, SERT) mRNAexpression in the dorsal raphe nucleus (DR), the main source of serotonergic projections to anxiety-related brain regions, using in situ hybridization histochemistry.
UCN1 priming increased anxiety-related behavior in the SI test compared to vehicle-injected controls and elevated tph2, but not slc6a4, mRNA expression in DR subregions, including the ventrolateral DR/ventrolateral periaqueductal gray (DRVL/VLPAG), a subregion previously implicated in control of panic-related physiologic responses. Tph2 mRNA expression in the DRVL/VLPAG was correlated with increased anxiety-related behavior.
Our data support the hypothesis that chronic anxiety states are associated with dysregulated tph2 expression.