Abstract

Dietary content/habit is known to play a prominent role in memory function, in part via a direct effect of ghrelin on the hippocampus. Given the role of ghrelin in regulation of central dopamine release, ghrelin impact on learning and memory may also be indirect via dopamine. Here, we examined effect of scheduled-diets and different amounts of calorie intakes on hippocampal dopamine content and memory performance as well as correlation between plasma ghrelin and hippocampal dopamine. Forty male Wistar rats (180–200 g) were divided into four groups (n = 10): freely fed (control) and three scheduled-fed groups with different caloric intakes; high fat, standard and restricted diets, and were maintained on each feeding program for 16 days. At day 16, memory performance (using passive avoidance test) and circulating ghrelin were evaluated. The hippocampal homogenates were analyzed using HPLC with electrochemical detection to quantitate dopamine levels. The hippocampal dopamine was increased in scheduled-feeding rats compared to controls, with the highest level in the scheduled-restricted group (p < 0.01). There was a significant positive relationship between circulating ghrelin and hippocampal dopamine in anticipation of food in all scheduled-feeding rats compared to controls (p < 0.05 and p < 0.01). Memory improvement in standard scheduled-diet was significantly greater than non-scheduled-diet (control)> scheduled-restricted diet> scheduled-high fat diet (p < 0.001). These data indicate a differential effect of increased plasma ghrelin and hippocampal dopamine on memory performance in scheduled-diet groups, with enhanced memory in standard scheduled-diet and impaired memory in scheduled-high fat and restricted diets, suggesting nutritional balance and incentive signals of diet related to dopamine may be critical determinants of memory performance in scheduled-diets.

中文翻译：

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慢性标准计划饮食可提高记忆力，并与大鼠血浆 Ghrelin 和海马多巴胺水平呈正相关

摘要

众所周知，饮食内容/习惯在记忆功能中起着重要作用，部分原因是生长素释放肽对海马体的直接作用。鉴于 ghrelin 在调节中枢多巴胺释放中的作用，ghrelin 对学习和记忆的影响也可能是通过多巴胺间接影响的。在这里，我们检查了定期饮食和不同热量摄入量对海马多巴胺含量和记忆能力的影响，以及血浆生长素释放肽和海马多巴胺之间的相关性。40 只雄性 Wistar 大鼠（180–200 g）分为四组（n= 10)：自由喂食（对照）和三个不同热量摄入的预定喂食组；高脂肪、标准和限制饮食，并在每个喂养计划中维持 16 天。在第 16 天，评估记忆性能（使用被动回避测试）和循环生长素释放肽。使用具有电化学检测的HPLC分析海马匀浆以定量多巴胺水平。与对照组相比，定期喂养大鼠的海马多巴胺增加，其中最高水平在定期喂养组（p < 0.01）。与对照组相比，在所有计划喂养的大鼠中，循环生长素释放肽和海马多巴胺在预期食物方面呈显着正相关（p < 0.05 和p< 0.01)。标准计划饮食的记忆改善显着大于非计划饮食（对照）> 计划限制饮食> 计划高脂肪饮食（p < 0.001）。这些数据表明，增加的血浆生长素释放肽和海马多巴胺对计划饮食组的记忆表现有不同的影响，标准计划饮食中的记忆增强，而高脂肪和限制饮食中的记忆受损，表明饮食的营养平衡和激励信号与多巴胺相关的可能是预定饮食中记忆性能的关键决定因素。