Lack of synaptic vesicle protein SV2B protects against amyloid-β25–35-induced oxidative stress, cholinergic deficit and cognitive impairment in mice

• First demonstration of a link between synaptic vesicle SV2B and amyloid toxicity.
• SV2Bko are protected from amyloid induced memory deficits in several cognitive tasks.
• SV2Bko are protected from amyloid induced oxidative stress and cholinergic deficit.
• SV2Bko showed normal cognitive function in absence of challenge.
• We hypothesized that SV2B may be a key modulator of amyloid induced toxicity.

SV2B is a synaptic protein widely distributed throughout the brain, which is part of the complex vesicle protein machinery involved in the regulation of synaptic vesicle endocytosis and exocytosis, and therefore in neurotransmitters release. The aims of the present work were twofold: (1) phenotype SV2B knockout mice (SV2B KO) in a battery of cognitive tests; and (2) examine their vulnerability to amyloid-β25–35 (Aβ25–35) peptide-induced toxicity. SV2B KO mice showed normal learning and memory abilities in absence of Aβ25–35 injection. SV2B KO mice were protected against the learning deficits induced after icv injection of an oligomeric preparation of amyloid-β25–35 peptide, as compared to wild-type littermates (SV2B WT). These mice failed to show Aβ25–35-induced impairments in a number of cognitive domains: working memory measured by a spontaneous alternation procedure, recognition memory measured by a novel object recognition task, spatial reference memory assessed in a Morris water-maze, and long-term contextual memory assessed in a inhibitory avoidance task. In addition, SV2B KO mice were protected against Aβ25–35-induced oxidative stress and decrease in ChAT activity in the hippocampus. These data suggest that SV2B could be a key modulator of amyloid toxicity at the synaptic site.