five healthy men 25-38 years old were subjected to simultaneous composite intravenous stimulation tests of insulin hypoglycemia ( 0.1 u/kg ) , thyrotropin-releasing hormone ( trh , 100 mug ) , and luteinizing hormone-releasing hormone ( lhrh , 50 mug ) at weekly intervals to study the circadian responsiveness of the hypothalamic-adenohypophyseal axis at 0600 , 1200 , 1800 , and 0000 hours .
C0023610
lhrh
C0020663
hypothalamic