Open Journal of Social Sciences
2013. Vol.1, No.6, 23-25
Published Online November 2013 in SciRes (http://www.scirp.org/journal/jss) http://dx.doi.org/10.4236/jss.2013.16005
Open Access 23
Salivary Amino Acids Determination and Their Changes in
Vision Stress Experiments
Wei Tang1, Xuesong Li1, Xiaoxiao Wu1, Yu Wang1, Xuejun Kang1,2*
1Key Laboratory of Child Development and Learning Science of Ministry of Education,
Research Center for Learning Science, Southeast University, Nanjing, China
2Suzhou Key Laboratory of Enviroment and Biosafety, Southeast University, Suzhou, China
Email: *xjkang64@163.com
Received October 2013
Amino acid neurotransmitters represent a major class of compounds that are involved in neuronal com-
munication at CNS synapses, which can provide the basis for a variety of disease diagnosis and treatments
and the study of the mechanism of mental illness. An analytical method for the determination of several
amino acids in saliva was established with reversed-phase high performance liquid chromatography (RP-
HPLC) with UV detector. About ten kinds of amino acids were detected in saliva. Nine subjects have par-
ticipated in the stress experiments which have undergone a 50-min three-dimensional cartoon watching.
The result of the experiment has proved that four kinds of salivary amino acids respond to the vision
stress experiment obviously.
Keywords: Amino Acids; RP-HPLC; Stress Experiments
Introduction
Stress research in human health and diseases has occupied a
prominent position. According to the literature survey, about 75
to 90% of the diseases have a connection with the activation of
stress mechanisms. Many factors cause stress, such as mechan-
ical trauma, undercooling, overheating, food poisoning, psy-
chological fear, depression, heavily mental tension and so on.
Stress has a variety of assessment methods. Many indicators of
stress response can really and effectively show human being’s
physiological stress response system, such as cortisol, catecho-
lamines and so on. Among them the amino acid neurotransmit-
ters are important stress markers. Glutamate, aspartate, γ-ami-
nobutyric acid, glycine and taurine and many kinds of amino
acids are important neurotransmitters in brain. Glutamate and
aspartate are considered to be excitatory amino acids; while γ-
aminobutyric acid, glycine and taurine are considered to be in-
hibitory amino acids. They are important materials which can
regulate the body's physiological activities. Thus separating and
determining the content of biological tissue’s amino acid neu-
rotransmitters can provide a basis for the diagnosis and the
treatment of many diseases and mental illness’ mechanisms. As
a result, the determination and study of stress amino acids are
really important (Xuejun Kang, Jing Xiao, Xiao Huang, &
Zhongze Gu, 2006).
Amino acids are regarded as important nutrients which can
directly involve brain protein synthesis and metabolism, (Spen-
cer GS, 1994) play an important regulatory role on the brain
function and psychological behavior. The researches of amino
acids and nervous system’s function can be traced back to the
forties and fifties last century. In recent years, neurotransmitters
and their receptors, neurophysiological and biochemical phar-
macology research also have many new developments (Yan SL,
Zhao G, & Liu YL, 2003). Studies have shown that some ami-
no acids are involved in learning and memorizing and some
other complex nervous activi tie s (Jones DP, Carlson JL, &
Samiec PS, 1998).
Kodama and co-workers found that concentrations of gly-
cine, alanine, threonine and histidine in the saliva are slightly
elevated, whereas those of glutamic acid and lysine are reduced
during the examination. The enhanced ratio of glycine/glutamic
acid may reflect the change from the excited state to the de-
pressed state (Nakamura Y, Kodama H, Satoh T, Adachi K,
Watanabe S, Yokote Y et al., 2010). Our group’s researches
imply that L-histidine in saliva may be another index in corre-
lation with human stress (Jing Sun, Xuejun Kang, Yuqin Ma,
Liqin Chen, Zijian Qu, Zhongze Gu, & Zuhong Lu, 2009) (Jing
Sun, Shenglan Zheng, Yu Wang, Xuejun Kang, Zhongze Gu, &
Zuhong Lu, 2010).
The aim of the present study was to use HPLC to determine
amino acids, and to evaluate the response of some salivary
amino acids on the learning process of people submitted com-
puter vision stress.
Experimental
Chemicals and Materials
Methanol (chromatographic purity) was from Chengdu Xin-
du area of the industrial development zone. (Chengdu, China).
Acetonitrile was from Shanghai Ludu Chemical Reagent Co.,
Ltd. (Shanghai, China). Triethyl ammonium was from Sino-
pharm Chemical Reagent Co., Ltd. Tetrabutyl ammonium hy-
droxide was from Shanghai Kefeng Industry Co., Ltd. (Shang-
hai, China). Dansyl chloride and amino acid standards were
from Sigma (St. Louis, MO). Acetone was from Shanghai
Lingfeng Chemical Reagent Co., Ltd. (Shanghai, China). Po-
tassium bicarbonate, potassium hydroxide and glacial acetic
acid were from Nanjing Chemical Reagent Co., Ltd. (Jiangsu
Province, China). Triply distilled water was used for all studies.
*Corresponding author.