Fig. 2
Overview of the study design in cohorts of heterozygous M83+/- mice. A In cohorts of transgenic M83+/- mice (12–14 weeks of age), phosphate buffered saline (PBS) vehicle (n = 5), monomeric (non-aggregated) aSyn (n = 5) or pre-formed fibrillar (PFF) aSyn (n = 18) were sterotaxically delivered bilaterally in the pontine GRN/Gi. Post-recovery, the mice were periodically assessed over time in tests of sensorimotor behaviors (green arrows, median interval between measurements: 15 days, unless indicated otherwise in the figure legends). Timed tissue collection was performed from the PFF-injected cohort after sacrifice at 30 and 60 days post-injection (DPI) (n = 3/time-point), or in the event of a humane endpoint (period is highlighted by the dashed red line). The PBS and monomer cohorts were euthanized at the termination of the study (Between DPI-120 and DPI-130). B Kaplan–Meier plot showing survival of transgenic M83+/- mice injected with PBS, monomeric aSyn or PFF aSyn bilaterally in the pontine GRN/Gi. The survival analyses do not include mice from the M83+/- PFF aSyn cohort terminated at DPI-30 and DPI-60 (timed-sacrifice, mentioned in A). The median time to moribund state for the heterozygous M83+/- was 124.5 days post-injection (9 out of 12 animals reached a terminal stage by DPI-129; the 3 remaining animals were euthanized at DPI-130 and not included/censored in the survival analyses). A small cohort of homozygous M83+/+ mice (n = 4) was also studied for comparison, in which the median time to a moribund state was 34.5 days. The PBS and monomeric injected mice M83+/- remained comparatively asymptomatic in gross motor performance (i.e. no foot-drop, paralysis or significant weight loss) over the duration of the experiment. Statistics in Fig. 2B: Log-rank Mantel-cox test (M83+/- cohorts: PBS, n = 5; monomeric aSyn, n = 5; PFF aSyn, n = 12 and M83+/+ cohort: n = 4; ****p < 0.0001; χ2, 42.28; df, 3). C Line graph showing the body weight measurements of the cohorts of heterozygous M83+/- mice over the duration of the study up to DPI-120. Statistics in Fig. 2C: Two-Way ANOVA with Geisser-Greenhouse correction (M83+/- cohorts: PBS, n = 5; monomeric aSyn, n = 5; PFF aSyn, n = 9–18; χ.2, 189.4; df, 1; Error bars, Mean ± SD; ns = not significant)