Rationale and objective

Environmental enrichment (EE) has been shown in old rats to improve learning and memory. Vitamin D (VitD) has also been shown to modulate age-related, cognitive dysfunction. As both EE and VitD could work to improve cognition via enhancement of neurotrophic factors, their effects might occlude one another. Therefore, a clinically relevant question is whether noted cognition-promoting effects of EE and VitD can co-occur.

Methods

Aged rats were housed for 6 weeks in one of three housing conditions: environmentally enriched (EE), socially enriched (SE), or standard condition (SC). Further, a 4th group was co-treated with VitD supplementation (400 IU kg⁻¹ daily, 6 weeks) under EE conditions (EE + VitD).

Results

Treatment with VitD and EE housing were associated with higher score on measures of learning and memory and exhibited lower anxiety scores compared to EE alone, SE or SC as assayed in the elevated plus maze, Morris water maze, passive avoidance, and open field tasks. Additionally, in the EE + VitD group, mRNA expression levels of NGF, TrkA, BDNF, Nrf2, and IGF-1 were significantly higher compared to expression seen in the EE group. Furthermore, field potential recordings showed that EE + VitD resulted in a greater enhancement of hippocampal LTP and neuronal excitability when compared to EE alone.

Conclusions

These findings demonstrate that in aged rats exposure to EE and VitD results in effects on hippocampal cognitive dysfunction and molecular mechanisms which are greater than effects of EE alone, suggesting potential for synergistic therapeutic effects for management of age-related cognitive decline.

中文翻译：

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维生素D与丰富环境的共处理可改善老年大鼠的突触可塑性和空间学习记忆

理由和目标

在老龄大鼠中已显示出环境富集（EE）可以改善学习和记忆能力。维生素D（VitD）也已被证明可以调节与年龄有关的认知功能障碍。由于EE和VitD都可以通过增强神经营养因子来提高认知能力，因此它们的作用可能相互排斥。因此，临床上相关的问题是，是否可以同时发生EE和VitD的显着认知促进作用。

方法

将老年大鼠在以下三种饲养条件之一中饲养6周：环境富集（EE），社交富集（SE）或标准条件（SC）。此外，第四组是与维生素D补充剂（400 IU公斤共同处理^-1每日，6周）EE条件下（EE +维生素D）。

结果

在高架迷宫，莫里斯水迷宫，被动回避和野外作业中，与单独使用EE，SE或SC相比，使用VitD和EE外壳进行治疗在学习和记忆方面得分更高，并且焦虑评分更低。另外，在EE + VitD组中，与在EE组中看到的表达相比，NGF，TrkA，BDNF，Nrf2和IGF-1的mRNA表达水平显着更高。此外，现场电势记录显示，与单独的EE相比，EE + VitD导致海马LTP和神经元兴奋性的增强更大。

结论

这些发现表明，在老龄大鼠中，暴露于EE和VitD会导致对海马认知功能障碍和分子机制的影响大于单独的EE的影响，表明可能具有协同治疗作用以管理与年龄有关的认知下降。