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Melatonin inhibits bone resorption in space!

Last Updated: December 11, 2019

Results of the experiment on fish scales conducted on the Japanese Experiment Module (JEM) "Kibo"/ISS in 2010 were published in the July 19, 2019 issue of an international scientific journal, Journal of Pineal Research. This experiment was conducted using the Cell Biology Experiment Facility (CBEF) installed on the JEM.

Theme of experiment

"Regulation of bone metabolism in space: Analysis using cultured goldfish scale as a model of bone" (Principal Investigator: Nobuo Suzuki, professor at Institute of Nature and Environmental Technology, Kanazawa University)


The experiment on fish scales conducted on the JEM "Kibo"/ISS has revealed that melatonin*1 inhibits bone resorption provoked in space. It is expected that melatonin will be utilized for developing preventive and curative medicines against loss of bone mass of astronauts in space.

The samples (regenerating scales) used for the experiment were transported on a space shuttle "Atlantis" launched on May 15, 2010 as the STS-132 mission to the ISS. These samples were then cultured in the CBEF in the JEM "Kibo" for four days from May 17, 2010. After that they were chemically treated and stored in freezer/refrigerator, and the experiment was completed on May 20. In parallel to the experiment under microgravity, a control experiment was conducted in a 1g compartment creating artificial 1G environment in the CBEF. Moreover, other samples were subjected to another control experiment on the ground. Stored samples were transported on the same space shuttle "Atlantis" back to the Earth as part of the STS-132 mission.

Fig 1. Goldfish scales in a container on JEM "Kibo" (Credit: JAXA)

Fig 2. Astronaut Soichi Noguchi working at the experiment on fish scales conducted on the JEM "Kibo" (Credit: JAXA)

※1 Melatonin
Melatonin (N-acetyl-5-methoxytryptamine) is a hormone that is categorized as an amine. It is secreted at night. It can be synthesized from triptophan (via serotonin). Important enzymes that participate in this synthesis may be allylalkylamine-N-acetyltrasferase (AANAT) and acetylserotonin-O-methyltransferase (ASMT). Melatonin is mainly produced by the pineal gland but is also known to be produced by other parts. It is a hormone that has been preserved in different species including vertebrates, invertebrates, plants and even cyanobacteria.

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