What is the relationship between melanin and the pineal gland? People who are only casually knowledgeable about melanin tend to confuse melanin with melatonin. There actually is a relationship between melanin and melatonin; the pineal gland. This article is an effort to clarify the differences between melanin and melatonin.
Melatonin is a hormone found in animals and humans. It is secreted in the pineal gland of the brain and other peripheral organs including the retina and gastrointestinal tract. The pineal gland is a pea-sized endocrine organ shaped like a pine cone in the middle of the brain. It regulates the circadian rhythms by varying the production of melatonin at different times of day. Circadian rhythms are biological processes that occur within a 24 hour timeframe or timed to the earth’s daily rotation through the phases of day to night and back again. Circadian rhythms have been occurring in living organisms including animals, plants and many tiny microbes for millions of years. The word circadian is from the LATIN words circa and diem. Circa means “around’ and diem means “day.” That indicates the rhythms rise and fall on a daily schedule.
The rate at which melatonin production occurs is controlled by a bundle of 20,000 nerves in the hypothalamus of the brain just above the optical nerves called the suprachiasmatic nucleus, or SCN. Melatonin is secreted by cells in the pineal gland known as pinealocytes. Melatonin secretion is inhibited by light entering the retina and stimulated by darkness.
Melanin on the other hand is produced in numerous areas of the body. In human skin and the choroid coat of the eye, melanocytes produce melanin. Melanin is also present in the locus coeruleus and substantia nigra.
The pineal gland was found to be calcified beginning in the second decade of life. Calcified pineal glands are found in American melanin-challenged people at approximately twice the rate as much the melanin-rich. This finding is more pronounced after age 40. American melanin-rich have “slightly higher” calcification, apparently due to genetic mixing.