Electroacupuncture improves V1 cortex synaptic plasticity via the CREB/BDNF/TrkB pathway in juvenile rats with monocular deprivation

The present study aims to investigate the impact of the CREB/BDNF/TrkB signaling pathway on synaptic plasticity in the visual cortex of juvenile amblyopic rats that have undergone monocular deprivation (MD). This study involved sixty 2-week-old Sprague-Dawley (SD) juvenile rats, which were not specified by gender. In the first part of the study, 24 rats were randomized into control and MD groups; In the second part, 36 rats were randomized into MD, electroacupuncture (EA) and EA + CREB antagonist (666-15) groups. The MD model was established using the monocular suture method. 14 d after monocular suture, EA treatment was started for 30 min daily, at a frequency of 2-10 Hz and an intensity of 1 mA, for 2 weeks. According to the results from part 1, the P100 wave latency in the MD group was prolonged, and its amplitude was lower compared to the control group. Additionally, the neuron number in the V1 cortex of the MD group decreased, along with reduced expression levels of CREB, BDNF, p-TrkB, and the key plasticity proteins PSD95 and SYN. In part 2, EA treatment significantly increased the electrophysiological activity of neurons in V1 cortex, shortened the latency of P100 peaks to varying degrees, increased the amplitude significantly, and restored the morphology and structure of neurons to normal levels; The expression of synaptic proteins PSD95 and SYN, as well as the expression of signaling molecules CREB, BDNF, and p-TrkB proteins were increased. However, the effects of EA were reversed when the specific CREB inhibitor 666-16 was administered. These data indicate that EA enhances the expression of V1 cortical synaptic plasticity-related proteins by regulating the expression of CREB/BDNF/TrkB signaling pathway, thereby enhancing V1 neural synaptic plasticity and reversing the effects of MD on visual acuity.