Ozaki Y, Lynch H J
Endocrinology. 1976 Aug;99(2):641-4. doi: 10.1210/endo-99-2-641.
Melatonin was shown to occur in rat plasma and urine after pinealectomy by bioassay, radioimmunoassay, and thin-layer chromatography. Total daily excretion of melatonin in pinealectomized rats was about 20% of control. Light-dark rhythms of plasma melatonin levels and urinary excretion rates disappeared after pinealectomy.