达能营养中心第七届学术研讨会论文集
田惠光 于志杰 程义勇 王冬兰 李树田 陈伟强
天津市卫生局公共卫生监督所，天津 300050；天津卫生学环境医学研究所，天津 300050
1前言
心理应激诱发的神经内分泌系统反应涉及到体内多种激素和神经递质、累及多个系统和器官，因而对机体健康的影响很大。大量研究表明，长期的或严重的应激反应在多种疾病的发生、发展中有重要作用，精神异常、心脏病、糖尿病、癌症、高血压等都与心理应激的影响密切相关。
烟酸也称为维生素PP或维生素B3是尼克酸和烟酰胺（尼克酸酰胺）及具有烟酰胺生物活性的衍生物的统称，是碳水化合物和脂肪代谢的关键酶。烟酸在体内主要以烟酰胺腺嘌呤二核苷酸（NAD）和烟酰胺腺嘌呤二核苷酸磷酸（NADP）的形式发挥生理功能。研究表明，体内大约有200多种酶需要NAD和NADP的辅助在氧化还原反应中传递电子。早期研究发现烟酸缺乏糙皮病可同时伴随神经病症状如抑郁、无情感、头痛疲劳及丧失记忆，表明烟酸缺乏与心理行为改变密切相关；近年国外有研究发现应激反应与烟酰胺代谢过程相关，烟酰胺影响神经递质作用并增强神经系统的抗氧化作用，还有报道烟酰胺具有阻止脑细胞凋亡、坏死的功能。深入了解不同心理应激状态下的烟酸营养水平，了解补充不同剂量烟酸对应激适应性的影响，将为制定现代社会我国居民烟酸供给量标准提供科学依据，有助于提高我国居民的膳食营养和身体健康水平。
为了认识机体烟酸营养状况与心理应激的关系，我们采用动物实验、人体干预研究和体外神经细胞培养相结合的方法，系统观察了心理应激对机体烟酸代谢的影响及补充烟酸对心理应激适应能力的影响和可能的作用机制。
2材料和方法
选用雄性Wistar 大鼠１００只，按体重随机分为10组即对照组，对喂对照组, 烟酰胺缺乏对照组,低剂量烟酰胺补充对照组，高剂量烟酰胺补充对照组和相应应激组（表1）。动物饲料根据Zhang等（1993）和Rawling等（1994）报导的配方修改后配制而成。经实验饲料喂养一周后，对应激组大鼠进行束缚应激：每日６h，共２１d。
Table 1 Classification and treatment of rats
|
Study group |
NAM supplement |
Treatment |
|
(abbreviation) |
(mg/kg of diet) |
(number of rats) |
|
Control (C) |
20 |
Un-restrained (10) |
|
Restrained (10) | ||
|
Pair-fed (PF) |
20 |
Un-restrained (10) |
|
Restrained (10) | ||
|
NAM deficiency (ND) |
Not Available |
Un-restrained (10) |
|
Restrained (10) | ||
|
Low-dose
NAM supplement (LNS) |
40 |
Un-restrained (10) |
|
Restrained (10) | ||
|
High-dose
NAM supplement (HNS) |
500 |
Un-restrained (10) |
|
Restrained (10) |
Note, NAM: nicotinamide.
每周用电子天平（最大量程：2000g，精确度0.5g）对实验大鼠称量体重。于第一、二、五周末，固定将对照组、应激对照组、烟酰胺缺乏对照组、烟酰胺缺乏应激组、低剂量烟酰胺补充对照组和低剂量烟酰胺补充应激组大鼠各７只置不锈钢代谢笼内，收集２４h尿液。
束缚应激后２４h，各组大鼠进行旷场实验（open-field test）。旷场实验箱为一个100cm´100cm´50cm的箱体，箱底画有２５个相等方格。旷场实验进行３min，将大鼠置于实验箱中央格内，观察并记录其在中央格内的停留时间／潜伏期（latency），以穿格数（crossing）作为水平运动得分、直立次数（rearing）作为垂直运动得分并记录修饰次数（modification）。另外还记录了排便数。
皮质醇和胰岛素含量用北方生物技术研究所生产的放免试剂盒测定。尿中N1－甲基烟酰胺（NMN）采用荧光法（王喜生等，１９８7）。血浆总抗氧化能力、一氧化氮含量及肝脏一氧化氮合酶用南京建成生物工程研究所生产的试剂盒测定。血糖含量用中生北控生物科技股份有限公司生产的葡萄糖氧化酶法试剂盒测定。海马组织中精氨酸含量用酸水解法测定。肝组织金属硫蛋白含量用镉饱和法测定。
2.2 人体干预研究
公开招募受试对象。85人应征。参试条件设定为：男性，年龄：17-35岁，无肝病或胃部疾病史，实验前一周内无感冒，发热或影响参加实验的外伤或躯体障碍；实验前六个月内无严重精神刺激（包括：亲属不幸事件，本人或家庭重大变故等）。
经排除女性及35岁以上者，68名17－35岁男性同意参加实验。在告知实验详细内容后，受试者被随机分为两组，干预组35名，对照组33名；干预组给予NAM（20mg/d），对照组给予相同量淀粉（安慰剂），服用十天；共58名受试者完成了全部试验程序，干预组30名，对照组28名。
采用随机对照研究方法。实验前，确定了参试人员的年龄、受教育程度、身高、体重、血压、脉搏并进行了随机分组。采用问卷调查、症状自评量表（SCL-90）评定、复杂视觉反应和数字记忆广度测试对实验后两组有关心理指征进行了比较。收集了实验前后的血浆和淋巴细胞；实验前后及实验中期的晨尿。
2.3 体外神经细胞培养
无菌条件下,采用Sprague-Dawley胎鼠（孕18天）进行海马神经元原代培养。在海马细胞培养的第7天添加干预因素（CORT和NAM）。干预因素加入48h后，测定细胞存活率（MTT法）。每组设6个复孔，实验重复两次。
用实验饲料喂养一周后，不同实验组大鼠尿NMN排泄量出现显著变化（表３）。对照组和缺乏组大鼠尿NMN排泄量显著降低，而低剂量补充组显著升高。尿NMN排泄量反映机体烟酸营养的充盈程度，实验饲料喂养一周后，缺乏组大鼠尿NMN排泄量仅为对照组的1/4已处于烟酸营养缺乏状态但并未表现出明显的缺乏症状。经过随后三周的束缚应激，缺乏组和对照应激组大鼠尿NMN排泄量无明显变化，补充组大鼠尿NMN排泄量继续升高。与其相应的对照组比较，对照应激组和补充应激组大鼠的尿NMN排泄量都显著降低，表明应激时增加了烟酰胺的消耗。应激处理后，缺乏应激组大鼠尿NMN排泄量无明显变化，可能提示体内烟酸的耗竭。我们观察到在实验第四周（束缚应激两周）时缺乏组大鼠出现烟酸缺乏症状，表现为活动减少，毛色暗且粗糙，口周和爪部皮肤粗糙发红，实验后期甚至有血液渗出等明显的糙皮病症状。
应激处理后，应激组大鼠的血浆皮质醇含量与对照组相比明显升高（图1）。不同的烟酰胺营养状况与大鼠的血浆皮质醇含量也有显著的相关性。对照组大鼠的血浆皮质醇含量最高，低剂量补充组大鼠的含量最低（P <0.001）。
Table 2 Urinary excretion of N1-methylnicotinamide in rats with different nicotinamide nutritures and stress status during the study period (mg/24h, Mean ± SD, n=7)
|
Study group/period |
Week 1 |
Week 2 |
Week 5 | |||
|
|
|
| ||||
|
Un-restrained |
50.8 ± 13.8 |
37.8 ± 13.4 |
45.3 ± 12.2 | |||
|
Restrained |
53.4 ± 15.1 |
31.9 ± 11.9 |
31.5 ± 14.6 | |||
|
|
|
| ||||
|
Un-restrained |
59.2 ± 22.2 |
9.6 ± 4.2 |
9.9 ± 3.6 | |||
|
Restrained |
51.5 ± 15.2 |
8.2 ± 7.4 |
10.3 ± 2.1 | |||
|
NAM supplement1 |
|
|
| |||
|
Un-restrained |
55.1 ± 13.8 |
78.9 ± 46.9 |
135.0 ± 39.6 | |||
|
Restrained |
57.2 ± 24.1 |
84.6 ± 48.3 |
97.7 ± 48.2 | |||
|
P values |
NMN |
NMN ´ nutriture |
NMN ´ stress |
NMN´ nutriture ´ stress | ||
|
|
<0.001 |
<0.001 |
0.519 |
0.013 | ||
1Nicotinamide supplement was 40mg/kg in the diet.
烟酰胺营养状况和应激状况都对大鼠在旷场实验中的行为有显著影响（表3）。对喂组、缺乏组和高剂量补充组大鼠在中央格内的停留时间明显长于对照组和低剂量补充组。同时，烟酰胺营养状况和应激状况对大鼠潜伏期的影响存在着交互作用。高剂量补充对照组大鼠潜伏期高于应激组，而在其他各组则结果相反。该现象提示，体内烟酰胺高度蓄积可对正常状态下大鼠的行为产生抑制作用。
Figure 1 Relationships between latency time, plasma cortisol and glucose levels. A indicates all rats included, and B indicates only those restrained rats. PF: pair-feed, NAMD: nicotinamide deficiency, NAMS-L: low-dose nicotinamide supplement, NAMS-H: high-dose nicotinamide supplement.
另外，缺乏组和高剂量补充组大鼠的穿格次数低于其他组，表明过低和过高的烟酰胺营养状况都对大鼠的行为有不良影响。修饰次数以缺乏组最多，对喂组最低，这可能与缺乏组大鼠的糙皮病有关；对喂组修饰次数过低可能与其能量摄入不足有关。
Table 3 Behaviors in the open-field test of rats with different nicotinamide nutritures and stress status (Mean ± SD, n=10)
|
Study group |
Latency |
Crossing |
Rearing |
Modification |
|
|
(s) |
(time) |
(time) |
(time) |
|
|
|
|
| |
|
Un-restrained |
3.7 ± 2.3 |
45.8 ± 21.9 |
16.0 ± 12.6 |
2.6 ± 2.0 |
|
Restrained |
7.3 ± 6.1 |
47.8 ± 18.3 |
17.8 ± 6.6 |
4.8 ± 2.8 |
|
|
|
|
| |
|
Un-restrained |
12.9 ± 13.9 |
46.4 ± 9.6 |
16.0 ± 5.5 |
0.8 ± 1.0 |
|
Restrained |
19.9 ± 19.9 |
37.0 ± 19.4 |
14.0 ± 8.0 |
1.5 ± 1.7 |
|
|
|
|
| |
|
Un-restrained |
8.6 ± 9.9 |
35.9 ± 10.3 |
13.8 ± 5.4 |
5.7 ± 6.5 |
|
Restrained |
19.6 ± 23.3 |
28.1 ± 19.9 |
8.8± 4.8 |
4.2 ± 3.0 |
|
NAM supplement1 |
|
|
|
|
|
Un-restrained |
6.7 ± 5.0 |
44.3 ± 22.0 |
15.5 ± 6.8 |
3.5 ± 2.8 |
|
Restrained |
8.2 ± 5.2 |
50.2 ± 14.9 |
15.7 ± 5.2 |
2.8 ± 2.5 |
|
NAM supplement2 |
|
|
|
|
|
Un-restrained |
15.9 ± 10.7 |
21.3 ± 17.7 |
9.0 ± 7.4 |
2.3 ± 2.3 |
|
Restrained |
7.2 ± 5.1 |
38.8 ± 20.1 |
15.6 ± 6.6 |
2.8 ± 1.9 |
|
P values |
|
|
|
|
|
Nutriture |
0.028 |
0.005 |
0.089 |
0.004 |
|
Stress |
0.150 |
0.650 |
0.830 |
0.667 |
|
Nutriture´ stress |
0.017 |
0.124 |
0.135 |
0.131 |
1Nicotinamide supplement was 40mg/kg in the diet. 2Nicotinamide supplement was 500mg/kg in the diet. Note: Statistic test on the differences in the number of faces was not performed as only five rats had faces in the open-field test; the statistical power could not be reached. When the variances in latency and modification were tested, the naturally logarithmically transformed values were used.
束缚应激可能提高大鼠体内NO水平（P ＝0.055）但对NOS的水平无影响。增加烟酰胺摄入量可提高大鼠肝脏NOS含量（表5）。
烟酰胺营养状况对大鼠胰岛素水平有显著影响（表6）。对喂组大鼠血浆胰岛素水平最高，缺乏组最低。束缚应激后对喂应激组大鼠血浆胰岛素水平低于其对照组，而其它各组变化趋势相反。同时，补充烟酰胺也使补充组大鼠血糖高于其它组。
Table 4 Plasma total anti-oxidative capacity in rats with different nicotinamide nutritures and stress status (unit/ml, Mean ± SD, n=10)
|
Study group |
Un-restrained |
Restrained | |||
|
Control |
7.59 ± 1.48 |
8.88 ± 1.03 | |||
|
Pair-feed |
7.61 ± 1.60 |
6.65 ± 1.58 | |||
|
NAM deficiency |
5.22 ± 1.10 |
6.61 ± 1.79 | |||
|
NAM supplement1 |
8.42 ± 2.05 |
7.89 ± 2.42 | |||
|
NAM supplement2 |
6.61 ± 1.00 |
7.51 ± 1.33 | |||
|
All |
7.09 ± 1.83 |
7.50 ± 1.82 | |||
|
P values |
Nutriture |
Stress |
Nutriture´ stress | ||
|
|
<0.001 |
0.201 |
0.069 | ||
1Nicotinamide supplement was 40mg/kg in the diet. 2Nicotinamide supplement was 500mg/kg in the diet. TAOC: total anti-oxidative capacity.
Table 5 Plasma nitric oxide and liver nitric oxide synthase concentrations in rats with different nicotinamide nutritures and stress status (Mean ± SD, n=10)
|
|
NO |
NOS |
|
Study group |
(mmol/L) |
(unit/mg protein) |
|
|
| |
|
Un-restrained |
31.31 ± 10.30 |
0.27 ± 0.10 |
|
Restrained |
40.41± 26.23 |
0.23 ± 0.07 |
|
|
| |
|
Un-restrained |
46.16± 25.23 |
0.23 ± 0.06 |
|
Restrained |
66.70± 45.68 |
0.27 ± 0.11 |
|
|
| |
|
Un-restrained |
43.09± 13.16 |
0.26 ± 0.08 |
|
Restrained |
42.18± 19.67 |
0.31 ± 0.06 |
|
NAM supplement1 |
|
|
|
Un-restrained |
49.78± 31.40 |
0.53 ± 0.18 |
|
Restrained |
53.72± 42.26 |
0.48 ± 0.11 |
|
NAM supplement2 |
|
|
|
Un-restrained |
21.03± 9.67 |
0.59 ± 0.29 |
|
Restrained |
52.86± 37.43 |
0.48 ± 0.15 |
|
P values |
|
|
|
Nutriture |
0.086 |
<0.001 |
|
Stress |
0.055 |
0.475 |
|
Nutriture´ stress |
0.243 |
0.332 |
1Nicotinamide supplement was 40mg/kg in the diet. 2Nicotinamide supplement was 500mg/kg in the diet. Note: When the variances in nitric oxide and nitric oxide synthase concentrations were tested, the naturally logarithmically transformed values were used.
Table 6 Plasma insulin and glucose concentrations in rats with different nicotinamide nutritures and stress status (Mean ± SD, n=10)
|
|
Insulin |
Glucose |
|
Study group |
(mIu/ml) |
(mmol/L) |
|
|
| |
|
Un-restrained |
15.82 ± 2.54 |
8.40 ± 1.95 |
|
Restrained |
16.44± 3.55 |
8.26 ± 1.94 |
|
|
| |
|
Un-restrained |
24.07± 6.32 |
7.97 ± 1.68 |
|
Restrained |
20.16± 6.25 |
7.58 ± 2.82 |
|
|
| |
|
Un-restrained |
9.59± 4.97 |
7.36 ± 1.87 |
|
Restrained |
14.18± 4.86 |
8.15± 1.15 |
|
NAM supplement1 |
|
|
|
Un-restrained |
16.83± 3.60 |
8.64 ± 1.24 |
|
Restrained |
19.84± 2.21 |
9.52 ± 1.38 |
|
NAM supplement2 |
|
|
|
Un-restrained |
18.82± 2.70 |
9.18 ± 1.14 |
|
Restrained |
19.20± 2.72 |
8.94 ± 1.21 |
|
P values |
|
|
|
Nutriture |
<0.001 |
0.031 |
|
Stress |
0.390 |
0.609 |
|
Nutriture´ stress |
0.022 |
0.664 |
1Nicotinamide supplement was 40mg/kg in the diet. 2Nicotinamide supplement was 500mg/kg in the diet.
Figure 2 Liver MT concentrations in rats with different NAM nutritures and stress status (µg/g)
P values were equal to 0.034 for NAM nutritures and 0.043 for stress status, respectively.
3.2补充烟酰胺对人体应激适应性影响的随机对照研究
经计算机随机分组，干预组和对照组参试人员在年龄、受教育程度、体质指数、血压、脉搏、血浆皮质醇、NOS和NO含量等各项指标均无显著性差异（表7）。
Table 7 Baseline characteristics of the study subjects
|
|
Total
n=68 |
Intervention
n=35 |
Control
n=33 |
|
Age (years) |
21.9 ± 2.8 |
22.2 ± 3.1 |
21.5 ± 2.4 |
|
Education (≥ high school, %) |
78 |
80 |
76 |
|
BMI (kg/m2) |
23.3 ± 2.3 |
23.6 ± 2.5 |
22.9 ± 2.2 |
|
SBP (mmHg) |
103 ± 15 |
105 ± 10 |
101 ± 19 |
|
DBP (mmHg) |
67 ± 9 |
67 ± 11 |
67 ± 8 |
|
HR (min) |
72 ± 8 |
71 ± 8 |
73 ± 9 |
|
Cortisol (ng/ml) |
347.3 ± 87.5 |
360.1 ± 102.6 |
333.7 ± 66.8 |
|
NOS (unit/ml) |
30.8 ± 3.4 |
31.2 ± 3.3 |
30.3 ± 3.5 |
|
NO (µmol/L) |
38.7 ± 36.5 |
35.3 ± 38.7 |
42.7 ± 33.9 |
There is no statistical significance in the parameters between the two study groups.
经过10天的干预后，问卷调查显示干预组反映睡眠时间增加的比例显著高于对照组（P＝0.046）；SCL-90筛查阳性者比例、复杂视觉反应和数字记忆广度测试结果及副作用反映率未见差异的显著性（表8,9）。
Table 8 Self-reported reactions to the intervention
|
|
Intervention
n=30 |
Control
n=28 |
Significance
(P value) |
|
Appetite increase (%) |
32 |
18 |
0.205 |
|
Sleep prolonging (%) |
32 |
11 |
0.046 |
|
Sleep quality improvement (%) |
36 |
25 |
0.382 |
|
Mood improvement (%) |
32 |
32 |
0.992 |
|
Nausea (%) |
3 |
7 |
0.494 |
|
Headache (%) |
19 |
11 |
0.357 |
|
Fidget (%) |
16 |
14 |
0.844 |
Table 9 Psychologic assessment after the intervention
|
|
Intervention
n=30 |
Control
n=28 |
Significance
(P value) | ||
|
SCL-90 positivea (%) |
30 |
25 |
0.670 | ||
|
Sight reaction | |||||
|
Time (s) |
3408.1 ± 978.3 |
3676.1 ± 776.9 |
0.255 | ||
|
Error frequency |
10.6 ± 5.7 |
10.4 ± 9.3 |
0.904 | ||
|
Digit memory reactionb |
17.7 ± 3.9 |
16.5 ± 3.5 |
0.207 | ||
Note, a, SCL-90 positive defined as either total score ≥160 or the number of positive items ≥ 43 or both. b, full score is 28.
经干预和给予应激刺激后干预组和对照组的血压和脉搏无显著性差异；另外未发现两组间血浆尿皮质醇含量的差异及血浆NOS含量差异的显著性；但干预组血浆NO含量显著高于对照组（表10，图3）。
Table 10 Biological assessments after the intervention
|
|
Intervention
n=30 |
Control
n=28 |
Significance
(P value) |
|
SBP (mmHg) |
109 ± 11 |
108 ± 12 |
0.725 |
|
DBP (mmHg) |
65 ± 8 |
65 ± 8 |
0.976 |
|
HR (min) |
71 ± 6 |
73 ± 9 |
0.203 |
|
Cortisol (ng/ml) |
291.6 ± 97.1 |
278.5 ± 79.2 |
0.585 |
|
NOS (unit/ml) |
35.6 ± 4.3 |
33.9 ± 5.5 |
0.195 |
Figure 3 Differences in NO concentrations between intervention and control groups after NAM supplementation and psychological stress
由RT-PCR反转录扩增得到的GAPDH和iNOS产物，经琼脂糖凝胶电泳后得到的条带结果未见差异的显著性（图4）。
Figure 4 Differences in iNOS mRNA expression between intervention and control groups after NAM supplementation and psychological stress
干预组于实验中期NMN排出量最高（实验前2倍），应激刺激后减少到略高于实验前水平。对照组NMN排出量于实验后持续降低，应激刺激后仅为实验前水平的1/2（图5）。不同组间NMN排出量及排出量的变化趋势均有显著性差异。
Figure 5 Urinary excretion of NMN during the study period
Analyzed by the repeated measurement of ANOVA, P = 0.002 for NMN measurements in groups with different nicotinamide nutritures; and P = 0.004 for NMN measurement and nicotinamide nutriture interactions.
3.3 烟酰胺对皮质酮致原代培养大鼠海马神经元损伤的保护作用
CORT在10μM浓度即可以造成细胞损伤，存活率显著降低，并随浓度增加存在剂量－效应关系（图6）。
Figure 6 Cell survival rates with different level of corticosterone treatment
* Indicates that cell survival rate is significantly different from the control (P<0.05). P<0.001 for the overall mean.
较高浓度NAM可使细胞存活率显著下降，而较低浓度则对细胞存活率无明显影响（图7）。
Figure 7 Cell survival rates with different levels of NAM treatment
* Indicates that cell survival rate is significantly different from the control (P<0.05). P<0.001 for the overall mean.
与对照组相比，100μMCORT使细胞存活率显著降低（67±6.8％）。与单纯用CORT处理相比，CORT处理前12h用NAM进行干预可使细胞存活率显著上升，加入5mM和10mM后细胞存活率分别为94±9.0％和86±5.3％。与前述研究结果一致，加入低剂量NAM未对细胞存活率产生显著影响（5mMNAM：93±15.3％；10mMNAM：90±21.2％）（图8）。
Figure 8 Cell survival rates with NAM and CORT treatment
* and + indicate that cell survival rate is different from the corresponding control and CORT treated cells, respectively (P<0.05). P<0.001 for the overall mean.
4 总结
本研究采用动物实验、人体干预研究和细胞实验相结合的方法，以烟酰胺为烟酸营养补充剂较系统地研究了不同烟酸营养水平对应激动物旷场行为的影响及可能的作用机制；应激对人体烟酸代谢的影响，补充烟酰胺对人体应激相关心理、生理和生化指标的影响；预防性给予低浓度烟酰胺对较高浓度皮质酮对原代培养海马神经细胞损伤的阻断作用。
我们采用纯化饲料法使雄性Wistar大鼠具有了不同的烟酸营养状态；21d束缚应激产生动物应激模型。实验发现束缚应激可增加大鼠烟酸消耗；适量补充烟酰胺有助于提高大鼠的应激适应性。该作用可能是通过增加机体NO和血糖水平，增加葡萄糖的利用率和金属硫蛋白表达，维持机体在束缚应激下的抗氧化能力实现的。
人体实验采用随机、单盲、安慰剂对照研究方法，烟酰胺（20mg/d）连续补充10天后干预组反映睡眠时间延长的比例显著高于对照组。给予心理应激刺激后，干预组血浆NO含量显著高于对照组。补充烟酰胺使尿中NMN排出量显著增加，应激刺激使其排出量显著减少。提示应激可增加烟酸的消耗，适量补充烟酰胺可在应激状态下维持机体良好的烟酸营养状况，有助于提高应激适应能力。另外，复杂视觉反应和自觉心理指标反应如食欲增加，睡眠质量提高等虽然由于样本量较小无差异显著性，但均有改善趋势。
细胞实验研究发现，低剂量的皮质酮即可对原代培养的海马神经元造成损伤，显著降低存活率。较高剂量的烟酰胺也可使神经元存活率显著降低。而皮质酮加入前用低剂量的烟酰胺进行干预可有效防止皮质酮对海马神经细胞的损伤作用。
上述结果提示，心理应激可显著增加机体烟酸的消耗；烟酸缺乏和补充过高剂量的烟酰胺均可对机体的应激适应能力产生不利影响；适量补充烟酰胺不仅可维持机体应激状态下的烟酸营养水平，而且可提高应激适应能力，有效保护机体免于过高水平应激激素对机体，特别是神经细胞的损伤作用。更深入地了解不同心理应激状态下的烟酸营养水平，了解补充不同剂量烟酸对应激适应性的影响以及烟酸与其它营养素对应激适应能力影响的协同作用将为制定现代社会我国居民烟酸供给量标准提供科学依据，提高我国居民的膳食营养水平和身体健康。
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