Table 1.

Half-life of α-Syn in primary mouse cortical neurons at different maturation stages

DIV	t1/2 fast (%)	t1/2 slow (%)	t1/2 total	R2
7	2.3 ± 0.4 (29.9)	53.6 ± 4.2 (70.1)	26.5 ± 2.6	0.996
14	5.4 ± 0.7 (19.3)	72.5 ± 6.6 (80.6)	50.5 ± 5.4	0.998
35	NA	115.5 ± 10.7	115.5 ± 10.7	0.956
42	NA	160.1 ± 14.7	160.1 ± 14.7	0.927

The half-lives were extrapolated from the pulse-chase study by regression analyses assuming that the decay of α-Syn follows either biphasic exponential decay [y = f(e^−k1x) + f2(e^−k2x), where f₁ (fast) + f₂ (slow) = 1 (initial amount of the labled α-Syn) and k₁ and k₂ represent the rate of decay for each decay component] or monophasic exponential decay [y = f(e^−kx)]. For the biphasic decay, the half-lives (expressed in hours) of the two individual phases were calculated from 0.69/k₁ (fast) and 0.69/k₂ (slow), where 0.69 = log 2/log e. The total half-life, directly extrapolated from the plot, corresponds to the time point at which the remaining ³⁵S-labeled α-Syn equals 50% of the initial value. Also shown is the percentage of α-Syn in each decay phase (%) representing f_x × 100. Correlation coefficients (R²) show the goodness-of-fit for the equations used. Values are from three independent cultures and are expressed as mean ± SEM. NA, Not applicable. All values are significantly different from each other (p <0.01; t test).