Exercise improves recognition memory and synaptic plasticity in the prefrontal cortex for rats modelling vascular dementia

Abstract

Objectives: Functional electrical stimulation (FES) may induce involuntary exercise and make beneficial effects on vascular dementia (VD) by strengthening the BDNF-pCREB-mediated pathway and hippocampal plasticity. Whether FES improves recognition memory and synaptic plasticity in the prefrontal cortex (PFC) was investigated by establishing a VD model.

Methods: The VD rats were administered with two weeks of voluntary exercise, forced exercise, or involuntary exercise induced with FES. Sham-operated and control groups were also included. The behavioral changes were assessed with the novel object recognition test and novel object location test. The expression levels of key proteins related to synaptic plasticity in the PFC were also detected.

Results: All types of exercise improved the rats’ novel object recognition index, but only voluntary exercise and involuntary exercise induced with FES improved the novel object location index. Any sort of exercise enhanced the expression of key proteins in the PFC.

Conclusion: Involuntary exercise induced with FES can improve recognition memory in VD better than forced exercise. The mechanism is associated with increased synaptic plasticity in the PFC. FES may be a useful alternative tool for cognitive rehabilitation.

Keywords:

• Vascular dementia
• exercise
• functional electrical stimulation
• recognition memory
• synaptic plasticity

Abbreviations::

• AMPA: alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
• BDNF: brain-derived neurotrophic factor
• BSA: bovine serum albumin
• CaMKII: calcium/calmodulin dependent protein kinase II
• CREB: AMP-response element binding protein
• EGF: epidermal growth factor
• FES: functional electrical stimulation
• FGF: fibroblast growth factor
• GluR1: alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1
• LTP: long-term potentiation
• MAP-2: microtubule-associated protein 2
• NMDA: N-methyl-D-aspartic acid
• NOLT: novel object location test
• NORT: novel object recognition test
• NR1: N-methyl-D-aspartic acid receptor 1
• PFC: prefrontal cortex
• PSD-95: postsynaptic density 95
• SYN: synapsin I
• SYP: synaptophysin
• VD: vascular dementia

Acknowledgements

Authors thank Qiang Wang for helping with statistical analyses and useful suggestions in manuscript preparation.