EFFECT OF IRON AND ESTROGEN ON MELATONIN SECRETION BY THE CHICKEN PINEAL-GLAND

Estrogen effects on pineal secretion of melatonin are controversial. S ome feel that estrogen inhibits melatonin output in vitro but not in v ivo. Melatonin levels vary with the age in chickens where circulating estrogen levels also vary. Laying hens have minimal melatonin levels a nd maximal serum iron concentrations. Thus, we reasoned that iron rele ased by estrogen may inhibit melatonin secretion from the chick pineal gland. The present study shows that perifusion of estrogen-treated ch ick pineal glands with several concentrations of iron greatly inhibite d melatonin secretion.