Western blot detection of BDNF in subcellular fractions of superior colliculus from 3, 6 and two sets of 10 month DBA/2J mice; three independent samples were pooled for each set. Mean IOP is indicated for the 10 month sets and was 15.7 for the 6 month samples. Detection of the synaptic vesicle membrane protein synaptotagmin (~65 kDa) was strongest in the light-membrane synaptosomal pellet (LP3), present but weaker in the high-speed vesicle fraction (P4), especially at 10 mo, and absent as expected in the high-speed supernatant of released vesicle content (LS4). In contrast, BDNF (~14 kDa) was weak and decreased with age in the LP3 fraction, was absent in the P4 fraction, and highly concentrated in LS4. Detection of β-Actin (~45 kDa) was used as a positive control.