坚果改善慢性应激致抑郁症大鼠行为学表现及其机制研究

为探讨坚果(核桃与甜杏仁)在抑郁症中的预防作用和机制.采用慢性温和不可预测应激(CMS)大鼠模型模拟抑郁症，对大鼠进行强迫游泳(FST)、糖水消耗的抑郁症行为学测试，并运用ELISA 试剂盒测定大鼠血浆皮质酮(CORT)含量，Western blot 法检测大鼠海马部脑源性营养因子(BDNF)、蛋白激酶A(PKA)和蛋白激酶C(PKC)的蛋白表达.实验结果表明，模型组FST、糖水消耗的行为学成绩明显低于正常对照组(P＜0.05)，预先给予坚果各剂量(60 g·kg－1、120 g·kg－1、240 g·kg－1)，可改善抑郁症大鼠的行为学成绩，提示，食用坚果可延缓抑郁症症状.血浆CORT水平测定结果显示，模型组血浆CORT含量显著高于正常对照组(P＜0.05)，但坚果各剂量组对血浆CORT含量无影响(P＞0.05)，提示，坚果产生延缓抑郁发生的机制可能与作用CORT途径无关联.对大鼠海马部的BDNF、PKA和PKC蛋白表达测定显示，模型组BDNF、PKA和PKC的蛋白表达均低于正常对照组(P ＜ 0.05)，而经预先给与坚果的各剂量坚果组，则拮抗了模型组BDNF、PKA和PKC蛋白表达水平的下降(P＜0.05).提示，坚果在预防抑郁症作用机制可能与激活PKA、PKC激酶和增强BDNF蛋白水平的信号通路有关.因此，本实验结果初步明确，预先食用坚果可有助于延缓抑郁症的产生.这将为后续食用坚果类食物在预防抑郁症中的研究提供了一定的理论和实验依据.

Effects of nut on improving behavioral performance of depressed rats induced by chronic stress and its mechanism

To explore the effect and mechanism of nuts (walnut and sweet almonds) on prevention of depression， chronic unpredictable mild stress (CMS) model was used to mimic depression. Immobility time in forced swimming test (FST)， sucrose consumption in sucrose preference test， corticosterone (CORT) levels in plasma， expression of brain-derived neurotrophic factor (BDNF)， protein kinase A (PKA) and protein kinase C (PKC) in hippocampus were measured respectively. Our results showed that the performance of behavior in model group was significant decrease compared with control group (P＜0.05). Pretreatment of nuts markedly improved the performance in FST and sucrose preference test. Nut group has a significant difference compared with model group (P＜0.05). These results suggest that pretreatment of nuts ameliorate the depression. In the test of CORT measured， although CORT level in plasma of model group was significant enhancement compared with control group (P＜0.05)， nuts group didn't decrease the CORT level in plasma compared with model group (P＞0.05). It suggested that prevention of depression of nuts might not be related to the reduction of CORT. In western blot test， hippocampal expression of BDNF， PKA and PKC in model group was significant decrease compared with control group (P＜0.05). On the contrary， pretreatment of nuts reversed the reduction of the expression of BDNF， PKA and PKC compared with model group (P＜0.05)， suggesting that antidepressant effect of nuts is related to activate PKA， PKC and increase the expression of BDNF signaling pathway. Therefore， these results suggest that pretreatment of nuts alleviate the depression， providing theories and experimental foundation for prevention of depression through eating nuts.