Objective:To study the influence of laboratory mental stress on plasma levels of angiotensin II (Ang II), aldosterone(ALD)and atrial natriuretic peptide (ANP) in individuals with different salt sensitivity Method:48 healthy male undergraduates were divided into salt sensitive group (SS group, n=14) and non-salt-sensitive group (NSS group, n=34) Their blood pressure, plasma levels of Ang II, ALD and ANP were measured before and after mental arithemtic test Result:Blood pressure, plasma levels of Ang II and ALD increased significantly in both groups, with SS group having greater increase Plasma level of ANP had no change after the test Conclusion:Laboratory mental stress increases the plasma levels of Ang II and ALD in male students Salt-sensitivity can magnify this effect

Objective To investigate the protective effect and mechanism of environmental enrichment(EE)on radiation induced cognitive dysfunction in mice.Methods A total of 45 female Kunming mice(2-month old)were randomly divided into control group,irradiation group and irradiation plus EE group with 15 in each group.Irradiation group and irradiation plus EE group were treated with a single dose of 4 Gy whole body irradiation,irradiation plus EE group were housed in EE condition for 35 d after irradiation.The object recognition task was used to evaluate the cognitive function of mice.The expression of microglial marker IBA-1 in hippocampus was determined by immunohistochemical staining.The expressions of CD68 and synaptophysin(SYP)proteins in hippocampus were assayed by Western blot.Results Compared with control group,the irradiation group had a low discrimination ratio in object recognition task and had a remarkable low level of SYP expression in hippocampus(t＝3.66,6.84,P＜0.05).In addition,radiation activated microglia in hippocampus by increasing the number of IBA-1-positive cells and enhancing the expression of CD 68(t ＝6.83,5.79,P ＜0.05).Compared with irradiation group,irradiation plus EE group increased the discrimination ratio and the expression of SYP in hippocampus(t＝3.56,4.06,P＜0.05),while the number of IBA-1-positive cells and the expression of CD68 were significantly reduced(t＝7.69,4.59,P＜0.05).Conclusions A single dose of 4 Gy whole body irradiation leads to cognitive dysfunction in mice,while EE could effectively improve the animals′cognitive behavior possibly by inhibiting microglial activation and preventing synapse loss in hippocampus.