Department of Pharmacology, Ladoke Akintola University of Technology, Osogbo, Osun State, Nigeria.
Department of Anatomy, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
Naunyn Schmiedebergs Arch Pharmacol. 2017 Jul;390(7):677-689. doi: 10.1007/s00210-017-1371-6. Epub 2017 Mar 29.
The present study investigated changes in behaviour associated with oral monosodium glutamate (a flavouring agent), using the open field, elevated plus maze and conditioned place preference (CPP) paradigms, respectively. Mice were assigned to two groups for CPP [monosodium glutamate (MSG)-naïve (n = 40) and MSG-pretreated (n = 40)] and two groups for open field (OF) and elevated plus maze (EPM) tests [n = 40 each], respectively. Animals in respective groups were then divided into four subgroups (n = 10) (vehicle or MSG (80, 160 and 320 mg/kg)). MSG-naïve mice were observed in the CPP box in three phases (pre-conditioning, conditioning and post-conditioning). Mice were conditioned to MSG or an equivalent volume of saline. The MSG pretreatment group received vehicle or respective doses of MSG daily for 21 days, prior to conditioning. Mice in the OF or EPM groups received vehicle or doses of MSG (orally) for 21 days, at 10 ml/kg. Open field or EPM behaviours were assessed on days 1 and 21. At the end of the experiments, mice in the OF groups were sacrificed and brain homogenates used to assay glutamate and glutamine. Results showed that administration of MSG was associated with a decrease in rearing, dose-related mixed horizontal locomotor, grooming and anxiety-related response and an increase in brain glutamate/glutamine levels. Following exposure to the CPP paradigm, MSG-naïve and MSG-pretreated mice both showed 'drug-paired' chamber preference. The study concluded that MSG (at the administered doses) was associated with changes in open field activities, anxiety-related behaviours and brain glutamate/glutamine levels; its ingestion also probably leads to a stimulation of the brain reward system.
本研究分别采用旷场实验、高架十字迷宫实验和条件性位置偏爱（CPP）实验，研究了与口服单谷氨酸钠（一种调味剂）相关的行为变化。将小鼠分为 CPP 两组[单谷氨酸钠（MSG）-未处理组（n=40）和 MSG 预处理组（n=40）]和旷场（OF）和高架十字迷宫（EPM）两组[每组 n=40]。然后，将各组动物分为四个亚组（n=10）（载体或 MSG（80、160 和 320mg/kg））。在 CPP 箱中观察 MSG-未处理的小鼠在三个阶段（预条件、条件和后条件）的行为。将小鼠条件化至 MSG 或等量的盐水。MSG 预处理组在条件化前每天接受载体或相应剂量的 MSG 治疗 21 天。OF 或 EPM 组的小鼠接受载体或相应剂量的 MSG（口服）治疗 21 天，剂量为 10ml/kg。在第 1 天和第 21 天评估 OF 或 EPM 行为。实验结束时，OF 组的小鼠被处死，脑匀浆用于测定谷氨酸和谷氨酰胺。结果表明，MSG 的给药与增加脑谷氨酸/谷氨酰胺水平、减少垂直运动、水平运动、理毛行为和与焦虑相关的反应有关。暴露于 CPP 范式后，MSG-未处理和 MSG-预处理的小鼠均表现出对“药物配对”室的偏好。该研究得出结论，MSG（在所给剂量下）与旷场活动、焦虑相关行为和脑谷氨酸/谷氨酰胺水平的变化有关；其摄入可能会刺激大脑奖励系统。
