Fig. 1

Nicotinamide limits mitochondrial morphological changes in the retina following inhibition of complex I. (A) Mice received intravitreal injection of rotenone (ROT) or vehicle control (DMSO). Mice were either pretreated with NAM or remained untreated. (B) Significant RGC (RBPMS +) degeneration occurs 1 day after injection of rotenone, in the absence of gross loss of GCL nuclei (DAPI +), supporting a critical vulnerability of RGCs to complex I loss. NAM provides a partial neuroprotection against this loss of RGCS. (C) In MitoV mice, high resolution imaging of the NFL/GCL allowed RGC specific YFP + mitochondria in RGC axons and somas to be captured for 3D reconstruction. (D) Morphological analysis (average of all mitochondria per retina in box and whisker plots; individual mitochondria/aggregates in raincloud plots) of these mitochondria revealed that rotenone induced a significant increase in mitochondrial volume, likely from the aggregation of damaged mitochondria in the soma. NAM treatment prevented these changes, with morphological features more reflective of normal controls (DMSO). (E) High resolution imaging of the IPL allowed RGC specific YFP + mitochondria in RGC dendrites to be captured for 3D reconstruction. (F) Morphological analysis demonstrated a reduction in mitochondria numbers in the IPL following rotenone injection, in the absence of detectable changes to morphology. NAM treatment in the absence of complex 1 inhibition (DMSO + NAM) resulted in larger mitochondria in the IPL. Scale bar = 20 µm in A. * P < 0.05, ** P < 0.01, *** P < 0.001, NS = P > 0.05