Melatonin: The Body’s Multitasker

Mention melatonin and many people think of the over-the-counter sleep aid. But it turns out the hormone made in the brain’s pineal gland does a lot more than support slumber.

New research confirms for the first time the multitude of roles that naturally occurring melatonin plays in the body, modulating everything from circadian rhythms to reproduction to “torpor,” an energy-conserving state similar to short-term hibernation that could be induced in humans during long space travel.

The study, conducted by a team of scientists from the University at Buffalo, RIKEN in Japan and other institutions, is the first to give definitive proof of what endogenous (naturally occurring) melatonin does. That’s because it was done on two genetically identical mice: one that produced melatonin and one that did not. Prior studies involved removal of the pineal gland, which blocked production of other molecules along with melatonin, making it unclear where the observed effects were coming from.

“Now we can test the effect of endogenous melatonin on reproduction, torpor, body weight and other physiological functions,” says Margarita L. Dubocovich, senior author on the paper and SUNY Distinguished Professor of Pharmacology and Toxicology in the Jacobs School of Medicine and Biomedical Sciences at UB.

“These results can be used to advance the understanding in how endogenous melatonin affects mice behavior and physiology,” she adds, “which could then provide insights into the role of endogenous melatonin in humans.” Dubocovich has pioneered research over the past several decades on the role of melatonin in mammals, driven by a “passion to discover new treatments for depression using drugs that target melatonin receptors.”

The researchers determined that melatonin does the following:

• Facilitates re-entrainment, the alignment of the body clock to the outside world.
• Decreases body weight.
• Decreases reproductive performance.
• Induces daily torpor (an energy-conserving function in animals).

They also settled the question of whether melatonin, which has been proposed as a possible anti-aging agent, has any life-extending effects. The study showed it does not.

However, there is still much more to explore. The findings pave the way for further investigations into the role of this multitasking hormone in the immune system, bone formation, inflammation and actions on peripheral tissues involved in metabolic function, such as the pancreas and liver.