Ultrastructural analysis of PF/PC synapses in wild-type and BDNF −/− mice
| Vesicles/synapse (± SEM) | PSD (nm) | DV/μm PSD | Ratio docked/total | Vesicles/μm2 | |
|---|---|---|---|---|---|
| Longitudinal sections | |||||
| +/+ | 49.8 ± 2.9 | 455.8 ± 12.1 | 20.9 ± 0.7 | 0.247 ± 0.01 | 346.1 ± 8.4 |
| −/− | 64.4 ± 3.2* | 517.1 ± 13.4* | 20.5 ± 0.7 | 0.193 ± 0.01* | 307.8 ± 5.8* |
| *p < 0.01; BDNF +/+ (172 synapses); BDNF −/− (177 synapses) | |||||
| Cross sections | |||||
| +/+ | 18.9 ± 1.8 | 355.6 ± 14.2 | 17.4 ± 0.9 | 0.373 ± 0.02 | 347.8 ± 11.9 |
| −/− | 33.1 ± 2.2* | 357.0 ± 9.4 | 15.9 ± 0.7 | 0.214 ± 0.01* | 250.1 ± 5.9* |
| *p < 0.01; BDNF +/+ (51 synapses); BDNF −/− (129 synapses) | |||||
BDNF −/− mice have a significant increase in the number of synaptic vesicles per terminal (Vesicles/synapse) and in longitudinal PSD length compared with wild type. However, no difference in the density of docked vesicles was detected (DV/μm PSD). Despite an elongated PSD, BDNF −/− terminals had a smaller fraction of all of their vesicles that was docked (Ratio docked/total). The overall packing density of vesicles in BDNF −/− terminals was also significantly decreased (Vesicles/μm2). Vesicles/synapse, Total vesicles per synapse; PSD (nm), postsynaptic density length; DV/μm PSD, docked vesicles per micrometer of active zone; Ves/μm2, overall vesicle packing density. Numbers are mean ± SEM;
↵* p < 0.01 by ttest.