Effects of Parabolic Flight on Serotonin-Related Gene Expression in the Mouse Brain

Mitsuhiro Yoshioka, Taku Yamaguchi, Hisashi Ohta, Jyunichiro Gyotoku, Mutsumi Miyamoto, Toshimasa Ochiai

Abstract


Exposure to uncontrollable stress triggers a wide range of adaptive changes in the central nervous system (CNS), including the elevation of serotonin metabolism and an increased susceptibility to affective disorders. The present experiment investigated alterations in gene expression levels, especially serotonin-related genes, in mouse brains exposed to gravity-changing stress using a competitive reverse transcription-polymerase chain (RT-PCR) reaction. Mice were exposed to gravity-changing stress during 8 parabolic flights. Serotonin and tryptophan transporters and tryptophan hydroxylase 2 mRNA levels in the midbrain were significantly increased 6 hr after the flight compared to pre-parabolic flight controls. In contrast, the 5-HT1A receptor, GAD65/67, and tyrosine hydroxylase mRNAs were not altered by the flight. These results suggest that the serotonergic system, particularly presynaptic synthetic pathways, were activated in the CNS by gravity-changing stress.

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