Cortisol -- the "stress hormone"

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"During World War Two rumors abounded that the Nazis were developing a miracle cure for stress so that their pilots could zoom around in their Messerschmitts with no regard to speed and altitude. The Germans were, supposedly, importing tons of bovine adrenal glands from Argentina and extracting some “mysterious humor” out of them. By then it was known to science that cows devoid of the glands died of even minimal stress, so the argument that the extract would make pilots stress-resistant seemed plausible. With hopes for outstanding military gains, the American government invested tons of money into the research on the mysterious humor, giving it the third priority after penicillin and antimalarials......" [excerpt from Growing Young]