Stress and the Nervous System

Inclusion Criteria: Subjects must be currently healthy, BMI 18-32 kg/m2, and not be on any medications. This study will recruit men and women. Due to concerns about estrogen's effects on hormone levels and possible contributions of menstrual symptoms on pain sensing thresholds, we will schedule the inpatient studies to avoid the early follicular phase in normally cycling women. Subjects must have normal laboratory values for: 1. Complete blood count 2. Serum creatinine, sodium, potassium, glucose, liver enzymes 3. Urinalysis 4. Urine pregnancy test (if female) 5. Normal ECG Exclusion Criteria: We will exclude individuals with: * Systolic blood pressure \> 140 or \< 90 mm Hg * Diastolic blood pressure \> 90 mm Hg * Creatinine clearance ≤ 60 mL/min, as calculated by MDRD formula * Known DM, CHF, CAD, PVD, CVA, MI, asthma * Known or history of Cushing's disease or adrenal insufficiency * Known neurologic disease * Known psychiatric disease * Steroid use (oral or inhaled, local or systemic injections, within the past 6 months) * Significant concomitant medical illnesses * Current excessive alcohol (\>10oz ethanol/week) * Current use of recreational drugs * Current smokers * Current pregnancy * Chronic use of non-steroidal anti-inflammatory or narcotic medications * Evidence of ischemia or heart block on screening electrocardiogram (greater than type I-second degree heart block, left bundle branch block, or ST-T wave changes in 2 or more contiguous leads) * Subjects taking any prescription medications (other than oral birth control pills) or herbal medications will be excluded.