Younglim Lee, Stephanie Fitz, Phillip L Johnson and Anantha Shekhar Repeated Stimulation of CRF Receptors in the BNST of Rats Selectively Induces Social but not Panic-Like Anxiety Younglim Lee, Stephanie Fitz, Phillip L Johnson and Anantha Shekhar

Background BNST identified as a key that relays and integrates limbic and autonomic info related to stress responses CRF given centrally induces anxiogenic behaviors in different models: EPM Social Interaction (SI) Open Field Conflict Test Acoustic Startle Conditioned Fear Response Both CRF1 & CRF2 receptors found in the BNST

Don't Do Drugs UCn1 = urocortin 1 – CRF agonist CRF receptor 1 & 2 agonist (suggested CRF1 receptor) Astressin – CRF antagonist – not receptor specific mmol (mili mole) is 1 x 10-3 moles µmol (micro mole) is 1 x 10-6 moles nmol (nana mole) is 1 x 10-9 moles pmol (pica mole) is 1 x 10-12 moles fmol (fempta mole) is 1 x 10-15 moles

Previous Studies Found Repeated priming injections into BLA w/ CRF receptor agonist Ucn1 at subthreshold dose induces long lasting behavioral change in SI & EPM Ucn1 priming in BLA produced anxiety behaviors and physiological sensitivity to IV sodium lactate infusions as seen in panic & PTSD disorders

Sodium lactate given IV induces panic (Johnson et al. 2007)

Sodium lactate given IV induces panic (Johnson et al. 2007)

Hypothesis & Investigation That acute stimulation of CRF receptors in BNST will anxiety & repeated stimulation will elicit persistent anxiety-like behaviors Investigated Effects of different UCn1 doses in BNST to determine subthreshold dose Effects of repeated daily intra-BNST Ucn1 injections of found subthreshold dose (UCn1 priming) Changes in lactate sensitivity following UCn1 priming of BNST

Animals Male Wistar Rats (275- 300g) Individually housed at 22C, food/water ad libitum 12h light/dark, lights on at 0700h

Surgical Procedures Implantation of telemetry probes Measuring Arterial pressure Heart rate Femoral arterial line connected to telemetric probe BNST cannulation Only unilaterally

Behavior Tests Social Interaction (SI) EPM Anxiety test Wooden box, place exp rat in with novel rat and video tape behavior Grooming, sniffing, playful behavior EPM

Exp. 1 -Injecting UCn1 in BNST (not adjacent area) will induce anxiety in rats measured in SI Results Fig a. suggest dose dependent reduction of SI following CRF receptor activation

Experiment 2 Repeated injections of UCn1 into BNST will lead to long-lasting anxiety

Exp. 2 Results UCn1 of 6-fmol dose (subthreshold)

Exp. 2 Results cont. No difference in EPM!

Experiment 3 Pretreatment w/ CRF antagonist will block development of Ucn1 priming in BNST Rats injected locally w/ Astressin- a nonselective CRF antagonist prior to daily UCn1 dose (6-fmol) Astressin- intransitive verb- (a \ˈstres\ inn) Used colloquially in times of great stress Example: I’m astressin OUT!!!

Exp. 3 results Astressin completely blocked UCn1 priming in the BNST

Experiment 4 UCn1 priming of BNST will not increase sensitivity to a subsequent challenge w/ sodium lactate

Exp. 4 Timeline

Exp. 4 Results

Exp. 4 Results cont. No change in SI or physiological responses w/ lactate infusion

Discussion UCn1 injected into BNST anxiety behavior Suggests CRF system in BNST regulates certain anxiety behaviors Decreases SI but no effect on EPM (only uni not bicannulated!) BLA primed rats had anxiogenic effects in SI & EPM UCn1 primed rats did not have panic-like cardiovascular responses to lactate infusion BNST critical in acquisition/expression social anxiety w/0 the physiological sensitivity to lactate (Clinical Implications)

Discussion cont. Authors note difference in SI for different strains of rats Wistar: 15-35s Sprague-Dawley: 40-70s Long-Evans: ??? SI recorded in “light cycle” 9am-1pm Acknowledge behavior test in dark cycle may increase SI

Discussion cont. Drug seeking behavior modulated w/ CRF in BNST circuitry Activation of CRF system for stress reinstatement of drug-seeking behavior CRF receptor antagonism blocks this stress effect BNST key to mediation inject CRF drug-seeking Inject CRF antagonist block drug-seeking behavior Pathophysiology similar to many mental disorders

Discussion cont. If social anxiety develops from CRF modulation in BNST & If CRF stimulation w/in BNST modulates drug- seeking behavior Then use UCn1 priming in BNST to search for vulnerability w/ substance abuse & psychiatric disorders

CRF1 & CRF2 Receptors UCn1 & astressin high affinities for both CRF receptors UCn1 in SI mediated CRF1 not CRF2 (Maybe? Prelim results) Anxiogenic effects of CRF in BNST from CRF1 receptors Drug-seeking from both CRF1 & CRF2

Take Home Repeated UCn1 priming into BNST = anxiety in SI but not EPM Primed rats failed lactate challenge = no HR or pressure increases! Priming may model social anxiety disorder!!! Repeated activation of BNST CRFR!!!

The End