A Pilot Study of Salivary MicroRNA Changes Due to High G-Load

Understanding physiological responses to high G-load is important for ensuring flight safety. In this pilot study, to establish a methodology for detecting salivary microRNAs (miRNAs) in humans before and after high G-load, we examined the relationship between miRNAs and high G-load or G-induced loss of consciousness (G-LOC), referencing previous concussion studies.

This study included 25 healthy pilot trainees attending centrifuge training for the primary course from June to October 2023. Saliva samples were collected at 3 time points: the day before centrifuge training (Pre), 3 h after training (Post1), and 20 h after training (Post2). Finally, miRNAs from 21 subjects, including 1 female, were analyzed using reverse transcription-quantitative polymerase chain reaction. Four miRNAs (miR-107, miR-34a-5p, miR-27a-5p, miR-30a-3p) were selected for analysis.

Salivary miRNAs from 4 of the 25 subjects could not be analyzed due to insufficient quality and quantity. Comparing the miRNA levels in 21 subjects at 3 time points, miR-107 at Post2 was significantly lower than that at Post1 (1.03 ± 0.39 vs. 1.32 ± 0.53). Of the 21 subjects, 16 did not experience G-LOC and 5 did. Comparing the levels between the no G-LOC and G-LOC groups at each point, only miR-34a-5p levels at Post1 were significantly different (1.11 ± 0.48 vs. 0.65 ± 0.11).

The key findings of this study were: 1) miRNAs suitable for analysis were extracted from the majority of saliva samples (21/25, 84%); and 2) changes in salivary miRNAs were detected by reverse transcription-quantitative polymerase chain reaction. Akiyama M, Takei F, Takada K. A pilot study of salivary microRNA changes due to high G-load. Aerosp Med Hum Perform. 2026; 97(2):106-110.