The purpose of this trial was to determine if injections of leptin would improve vascular function in normal-weight, healthy volunteers.

The researchers plan to enroll a total of 15 non-obese (BMI < 27 kg/m2) otherwise healthy adults into a randomized, double-blinded, cross-over study of the impact of recombinant methionyl human leptin 0.2 mg/kg SC, hereafter called rL, (Amgen Inc, Thousand Oaks, Calif) versus placebo SC (sorbitol and sodium acetate, pH 4.0 of same volume) in 15 non-obese adults. Subjects will have baseline vascular studies performed by brachial artery ultrasonography-flow-mediated dilatation and nitroglycerin mediated dilatation and blood drawn for measures of leptin levels. They will then receive rL SC or placebo SC (randomized order). They will then have vascular studies performed and blood levels drawn every 2 hours for 6 hours total. After completion of day 1, patients will return 1-4 weeks later and repeat the protocol crossed-over to the alternate intervention (rL or placebo).

Inclusion Criteria:

• Healthy male or female ages 18-50.
• BMI < 27 kg/m2 for lean group

Exclusion Criteria:

• Any CVD risk factor (diabetes or fasting glucose > 126 mg/dL
• Hypertension or measured BP > 140/90 mmHg
• Current tobacco smoking within last month
• LDL>160 mg/dL, HDL<35 mg/dL)
• Renal insufficiency (creatinine > 1.4 mg/dL)
• Thyroid abnormalities (abnormal TSH)
• Established CVD (any atherosclerosis, or history of peripheral arterial disease, previous stroke, myocardial infarction, angina, heart failure, aortic aneurysms)
• Usage of medications which impact endothelial function within last month (folate, fish oil, Vitamin C or E, L-arginine, blood pressure or lipid-lowering medications, diabetes medications)