Fig 1.
Study design (A) and its procedure (B). Participants were randomly assigned to one of two groups, and performed fatigue-inducing tasks with or without MCMP on successive days. Each study consisted of 40 min mental fatigue-inducing tasks (fatigue-inducing sessions) and two evaluation sessions (evaluation sessions). Each evaluation session was performed before and after each fatigue-inducing session.
Fig 2.
Screening of Hex-Hex Mix receptors from the human OR repertoire.
(A) 392 human ORs were stimulated with 10 ng/ml Hex-Hex Mix comprised 50 μM cis-3-hexanol and 50 μM trans-2 hexenal, respectively, and luciferase assay was performed. Fold increases were calculated as mentioned in the Materials and Methods section. (B) Dose response curves of each OR. The HEK293 cells transfected with each OR were stimulated by 0.3 to 10 ng/ml of Hex-Hex Mix and luciferase assay was performed. Fold increases are shown as means and SE (n = 3–6). *p < 0.05, **p < 0.01, ***p < 0.001, Fisher's LSD post-test.
Fig 3.
Screening new ligands of Hex-Hex Mix receptors.
Dose response curves of OR1A1, OR2J3, OR2W1, OR5K1, OR5P3 and OR10A6 for indicated odorants: Methyl ß -naphthyl ketone, l-carvone, methyl isoeugenol, phenylethyl acetate. The HEK293 cells transfected with each OR were stimulated by 0.1 to 300 or 1000 μM of these odorants and luciferase assay was performed. Fold increases are shown as means and SE (n = 3–5). *p < 0.05, **p < 0.01, ***p < 0.001, Fisher's LSD post-test.
Fig 4.
Screening of MCMP receptors from the human OR repertoire.
(A) 392 human ORs were stimulated with 50 ng/ml MCMP comprised 75 μM Methyl ß -naphthyl ketone, 75 μM l-carvone, 75 μM methyl isoeugenol and 75 μM phenylethyl acetate, respectively, and luciferase assay was performed. Fold increases were calculated as mentioned in the Materials and Methods section. (B) Dose response curves of common receptors between MCMP and Hex-Hex Mix: OR1A1, OR2J3, OR2W1, OR5K1, OR5P3 and OR10A6. The HEK293 cells transfected with each OR were stimulated by 0.6 to 200 ng/ml of MCMP and luciferase assay was performed. Fold increases are shown as means and SE (n = 3–5). *p < 0.05, **p < 0.01, ***p < 0.001, Fisher's LSD post-test.
Fig 5.
Subjective level of mental fatigue before and after the fatigue-inducing task.
Open columns indicate the VAS score in the MCMP condition and closed columns indicate the VAS score in the without-MCMP condition. Data are presented as mean and SE. **p < 0.01, paired t-test with Bonferroni correction.
Fig 6.
Change of correct response rate (%) in the cognitive task.
Left dots indicate the correct response rate in the MCMP condition, and right dots indicate the correction rate in the without-MCMP condition. Changes in correct response rate were found in Task B for non-Stroop trials before and after the fatigue-inducing task. Data are presented as mean and SE. *p < 0.05, significant difference (paired t-test with Bonferroni correction).