Relationship of NA and NAR, precursors of the Preiss-Handler pathway, with hearing thresholds
Hz(dB HL, Hz(dB
REGRESSION
Spearman’s rank correlation coefficient test was basically conducted to identify the correlation between NADWe first focused on the Preiss-Handler pathway, which uses dietary NA and NAPRT to generate NAMN that is subsequently transformed into NAAD by nicotinamide mononucleotide transferase (NMNAT) [Correlation between NA (nicotinic acid) levels and hearing thresholds at each frequency. Multiple linear regression analysis with hearing threshold as the dependent variable and age and NAD + metabolites (NA, NAM, and NAR) as independent variables R 1000 Hz(dB HL) R 2000 Hz(dB HL) L 1000 Hz(dB HL) L 2000 Hz(dB HL) L 4000 Hz(dB HL) L 250 Hz(dB HL)0.752(-0.00297) L 2000 Hz(dB HL) R 125 Hz(dB HL)-10,882(-31,840) L 1000 Hz(dB HL) L 2000 Hz(dB HL)(A, B and C) Multiple linear regression analysis with hearing threshold (dB HL) at each frequency as dependent variable and NA (μM) (A), NAM (μM) (B) or NAR (μM) (C) as independent variables, adjusted for ageThe values analyzed excluding outliers are presented in parentheses. *In addition, the same analyses were performed on the data set excluding outliers. Outliers were defined as values outside of the third quartile + 1.5 × quartile range as the maximum and the first quartile -1.5 × quartile range as the minimum. Even after excluding outliers, Spearman’s rank correlation tests still presented positive associations between NA levels and right or left-ear hearing thresholds at 1000 Hz (right: Further, we observed weak positive correlations of NA levels with right-ear hearing threshold at 4000 Hz (Next, we tested the correlation between the levels of NAR, which is converted from NA or NAMN in the Preiss-Handler pathway [