Progesterone Amplifies Estrogen-stimulated Growth Hormone Secretion in Older Women

Inclusion Criteria: * women ages 50 to 80 * postmenopausal as defined by: any combination of the following * Hormonally postmenopausal for 1 year * Lh greater than 15 IU/L, FSH greater than 30 IU/L * Total hysterectomy with oophorectomy greater than one year * Hysterectomy with ovaries preserved with hormone levels: Lh \> 15 IU/L, FSH \> 30 IU/L * Following laboratory results with normal range, unless PI approves out of range values. * BMI 18 to 35 Exclusion Criteria: * structural hypothalamo-pituitary-gonadal disease * endocrinopathy (diseases involving the following organs pituitary, thyroid, adrenals, ovaries, testes and pancreas), other than primary thyroid failure receiving replacement * recent (within 2 weeks) estrogen, progestin, anabolic steroid or glucocorticoid use * clinically significant ECG abnormality as determined by study team physicians * obstructive uropathy * history of a stroke * history of MI or angina * acute or chronic systemic disease * recent transmeridian travel (traversing more than 3 time zones within 7 days of admission) * current night shift work * concurrent use of neuropsychiatric medications * alcohol or drug abuse, current and within 2 years * history of depression, psychosis, or mania * weight gain or loss (2 kg or more in 3 weeks) * BMI \> 35 kg/m2 * anemia, hemoglobin less than 12.5 g/dl * abnormal hepatorenal function, creatinine outside normal range, ALT greater than two times normal range * biochemical and chemistry lab results out of physician acceptable range * history of deep-vein thrombophlebitis * history of Congestive Heart Failure, cardiac arrhythmias, and medications used to treat cardiac arrhythmias * known allergy to estradiol valerate, castor oil or sesame oil * history of smoking within the last 2 years * untreated gall bladder disease * lack of voluntary, written informed consent * history of carcinoma excluding localized basal cell or squamous cell, including women with known, suspected or history of breast cancer * not clinically postmenopausal * women with allergies to nuts will not be enrolled in the study.