The investigators are seeking healthy volunteers and volunteers with reproductive disorders for the study of the role of dynorphin in the reproductive system. Dynorphin is a naturally occurring opioid hormone that is blocked by naloxone.

We hypothesize that naloxone, by blocking dynorphin, will stimulate production of gonadotropin-releasing hormone (GnRH) and kisspeptin, two other naturally occurring reproductive hormones.

Inclusion Criteria:

• Ages 21-40 (healthy men and regularly cycling women) OR ages 18-75 (men and women with hypogonadotropic hypogonadism (HH))

• Normal blood pressure (systolic BP <140 mm Hg, diastolic BP <90 mm Hg)

• White blood cell, platelets, prolactin, and thyroid stimulating hormone (TSH)within 90%-110% of laboratory reference range

• Negative urine drug screen panel

• Hemoglobin:

  1. For healthy men and healthy regularly cycling women: normal
  2. For men and women with HH: No less than 0.5 gm/dL below the lower limit of the reference range for normal women

• Blood urea nitrogen (BUN), creatinine, liver function tests not elevated

• For healthy subjects: Normal reproductive function and history

• For healthy subjects: Body Mass Index (BMI) 18.5-30kg/m2

• For subjects with HH: All medical conditions stable and well controlled

Exclusion Criteria:

• History of medication reaction requiring emergency medical attention
• Illicit drug use
• Consumption of more than 10 alcoholic drinks per week
• Difficulty with blood draws
• Currently seeking fertility, breastfeeding, or pregnant
• For healthy subjects: history of chronic disease and prescription medication use (with the exception of seasonal allergy medication)
• For subjects with HH: prescription medications known to affect reproductive endocrine function except for those used to treat the subject's reproductive condition