1. CHEM E-120 Harvard University Extension School Spring 2011 Hypothalamus-Pituitary-Adrenal Neuroendocrine System HPA Axis 2/16/111CHEM E-120

2. 2 HPA Axis – Neuroendocrine System Hypothalamus Pituitary GlandAdrenal Gland (kidney) CRHACTH Cortisol Primary stress hormone CRF - corticotrophin releasing factor (CRH) ACTH - adrenocorticotropic hormone CRH1 and CRH2 GPCR receptors localized in pituitary, cortex, amyglada, LC, and hypothalamus Cortisol binds to glucocorticoid receptors (GR) and mineralocorticoid receptor (MR) Cortisol negative feedback action on the production of cortisol HPA axis is the major pathway by which stress is effected ACh + 5-HT + NE +/- GABA - Trends in Neuroscience 2008, 31, 464 Neurochem Res 2008, 33, 691 AVP – arginine vasopressin 2/16/11CHEM E-120

3. 3 CRF CRF - corticotrophin-releasing factor (corticotrophin-releasing hormone, CRH) 41 amino acid neuropeptide that initiates and regulates the HPA-axis response to stress CRF1 receptor has been implicated in anxiety and depression CRF antagonists are anxiolytic in animal models Hyperactivity of hypothalamic CRF neurons, overproduction of CRF Decreased levels of CRF 1 in frontal cortex of depressed patients Suggestion of CRF 1 desensitization Neural locations allow it to interact with multiple neurotransmitter systems PTSD - increased levels of CRF Mice overexpressing CRF have “high anxiety” phenotype CFR1 knockout mice display behavioral phenotypes of low anxiety Overexpression of CRF in mice increases anxiety behaviour Rats - administration of CRF produces anxiogenic state antagonized by DMP696 (CRF1 antagonist) CFR increases startle response in mice that is antagonized CNS & Neurological Disorders - Drug Targets 2007, 6, 163-182 Neurochem Res 2008, 33, 691 2/16/11CHEM E-120

4. Cortisol – Endocrine Hormone Major depression elevated serum levels of cortisol Functional and expression changes of glucocorticoid receptors (GR) Antidepressants increase GR expression, function, and feed-back inhibition Flattened diurnal rhythm (normal 16 μg/100 mL @ 8am, 4 μg/100 mL @4 pm) Biosynthetic pathway in the adrenal gland 2/16/114CHEM E-120

5. Comparison of the MR and GR Receptors Mineralocorticoid Receptor High affinity for cortisol Expression in hippocampus and amygdala Occupied when CORT is low and when CORT is high Agonist: Aldosterone Antagonist: RU26752 Glucocorticoid Receptor Low affinity for cortisol Expression in hippocampus, amygdala, hypothalamus, brain stem, cortex, pituitary Occupied when CORT is high Agonist: Dexamethasone Antagonist: RU38486 MR thought to mediate tonic control of cortisol cortisol K d < 10 -9 cortisol K d ~ 10 -8 Members of nuclear receptor superfamily – associated with heat-shock protein, when activated bind to specific DNA recognition sequences of target gene promoters, called hormone response elements 2/16/115CHEM E-120

6. Medication Development Based on HPA Axis Antidepressants may down regulate p-glycoprotein in the BBB increasing concentration of cortisol in CNS and re-equilibrate a faulty HP circuit. pGP actively transports cortisol out of the CNS. Inhibition of cortisol biosynthesis – aminoglutehimide (Cytadren), metyrapone, ketoconazole current inhibitors have high toxicity and have multitude side-effects GR antagonists – block action of excess cortisol, up-regulate GR expression (reinstall negative feedback loop) RU486 (Corcept) failed in Phase III trial, all are selective for GR versus MR but also bind to progesterone receptor (PR). CRH antagonists – block the CRF-mediated release of ACTH from the pituitary gland reducing the production of cortisol R121919 (Neurocrine/Janssen) showed positive antidepressant and anoxyltic effects in a 20 patient clinical trial ( Journal of Psychiatric Research 2000, 34, 171 ) but drug-induced reversible increases in liver enzymes were found. 2/16/116CHEM E-120

7. Journal of Psychiatric Research 2000, 34, 17 Effects of the high-affnity corticotropin-releasing hormone receptor 1 antagonist R121919 in major depression: the first 20 patients treated. “…suggesting that a complete blockade of the peripheral stress hormone system was unlikely… …basal corticotrophic activity is independent from CRH. 2/16/117CHEM E-120

8. Cortisol Levels on Awakening no statistical difference 2/16/118CHEM E-120

9. Night Cortisol Levels AUC calculation – significant differences vs control 2/16/119CHEM E-120

10. Bioorganic & Medicinal Chemistry Letters 2010, 1905 (BMS) 2/16/1110CHEM E-120

11. 11 CRF Antagonists - Pfizer CP-316311 CP-376395 CP-316311 Phase 2 depression JMC 2008, 51, 1377 CP-376395 JMC 2008, 51, 1385 pKa ∼ 3.6 solubility pH 2 = 3 μg/mL solubility pH 7 = 0.2 μg/mL pKa 6.9 solubility pH 2.4 = 5.4 mg/mL solubility pH 7 = 0.2 μg/mL greater bioavalibility 2/16/11CHEM E-120

12. CRF Antagonists - BMS 2/16/1112CHEM E-120

13. 2/16/1113CHEM E-120