Research Papers: Pathology:

Simulated weightlessness affects the expression and activity of neuronal nitric oxide synthase in the rat brain

Nara Yoon, Kiyong Na and Hyun-Soo Kim _

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Oncotarget. 2017; 8:30692-30699. https://doi.org/10.18632/oncotarget.15407

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Nara Yoon1, Kiyong Na2 and Hyun-Soo Kim2

1 Department of Pathology, The Catholic University of Korea Incheon St. Mary’s Hospital, Incheon, Republic of Korea

2 Department of Pathology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea

Correspondence to:

Hyun-Soo Kim, email:

Keywords: simulated weightlessness, neuronal nitric oxide synthase, rat, brain, tail suspension, Pathology Section

Received: December 29, 2016 Accepted: February 01, 2017 Published: February 16, 2017


Spaceflight induces pathophysiological alterations in various organs. To study pathophysiological adaptations to weightlessness on the ground, the tail suspension (TS) rat model has been used to simulate the effects of weightlessness. There is currently little information on the effect of TS on the expression and activity of nitric oxide synthase (NOS) in the brain. In this study, we examined time-dependent alterations in the expression and activity of neuronal NOS (nNOS) in the brains of TS rats. Male Sprague-Dawley rats were tail-suspended for 1 (TS1), 7 (TS7), and 14 (TS14) days or rested on the ground for 3 days after 14 days of TS. TS1 and TS7 rats exhibited no significant alterations in the expression of nNOS compared to control rats, whereas nNOS expression in TS14 rats was significantly upregulated compared to control rats. Normalized expression of nNOS mRNA and protein in TS14 rats (1.86 ± 0.48 and 1.84 ± 0.29, respectively) were significantly higher than that of control rats (P < 0.001 and P < 0.001, respectively). Consistent with these results, significant elevations in NOS activity and NO production were observed in TS14 rats. Thus, we demonstrated a significant upregulation of nNOS expression, accompanied by significant increases in NOS activity and NO production, in the brain of rats exposed to simulated weightlessness.

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