The present study aimed to investigate the effects of early and late administration of platelet-rich plasma (PRP) on learning-memory and hippocampal synaptic plasticity impairment in rat model of vascular dementia. Sprague-Dawley rats (6–7 weeks) were randomly divided into control, sham, 2VO + V (bilateral carotid vessel occlusion + vehicle), 2VO + E-PRP (early after 2VO), and 2VO + L-PRP (late after 2VO) groups. The injection of PRP started immediately or on the day 20 after 2VO in 2VO + E-PRP and 2VO + L-PRP, respectively, and continued until 28th day (two-time a week).

The passive avoidance and Morris water maze tests were used for evaluation of fear and spatial memory formation. The in-vivo long-term potentiation (LTP) was evaluated by field-potential recording, paired-pulse ratio (PPR) and input-output (I/O) curve which were monitored as indexes for evaluation of short-term plasticity (STP) and basal-synaptic transmission (BST), respectively.

The 2VO decreased PPR at inter-stimuli interval (ISI) 10 ms and BST, but injection of PRP in both treated groups rescued the PPR and BST depression. In addition, the induction of LTP, fear and spatial memory performance decreased in the 2VO + V group. However, early treatment, but not late, recovered LTP and memory.

The PPR and BST improved with early and late treatment; therefore, the number and time of injection seem to be not important for recovery of BST. However, we found that LTP and memory loss rescued only with early administration. Hence, timely injection, before development of the disease, or number of injections could be critical.

本研究旨在探讨早期和晚期给予富血小板血浆 (PRP) 对血管性痴呆大鼠模型学习记忆和海马突触可塑性损伤的影响。Sprague-Dawley 大鼠（6-7 周）随机分为对照、假手术、2VO + V（双侧颈动脉闭塞 + 载体）、2VO + E-PRP（2VO 后早期）和 2VO + L-PRP（后晚期） 2VO) 组。在 2VO + E-PRP 和 2VO + L-PRP 中立即或在 2VO 后第 20 天开始注射 PRP，并持续到第 28 天（每周两次）。

被动回避和莫里斯水迷宫测试用于评估恐惧和空间记忆的形成。通过场电位记录、双脉冲比（PPR）和输入输出（I/O）曲线评估体内长时程增强（LTP），这些曲线作为短期可塑性（STP）的评价指标进行监测。 ) 和基底突触传递 (BST)，分别。

2VO 降低了刺激间隔 (ISI) 10 ms 和 BST 的 PPR，但在两个治疗组中注射 PRP 挽救了 PPR 和 BST 抑制。此外，2VO+V组的LTP诱导、恐惧和空间记忆表现下降。然而，早期治疗，而不是晚期，恢复了 LTP 和记忆。

PPR和BST随着早期和晚期治疗而改善；因此，注射的次数和时间似乎对 BST 的恢复并不重要。然而，我们发现只有早期给药才能挽救 LTP 和记忆丧失。因此，在疾病发展之前及时注射或注射次数可能是至关重要的。