London, Apr 3 : Some people are known to deal with stress much better than others, and the key to this lies in a genetic factor, called neuropeptide Y (NPY) that governs this response variability, according to a study by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH).
According to the study, led by David Goldman, M. D., chief of the NIAAA Laboratory of Neurogenetics, inherited variations in the amount of NPY, an innate anxiety-reducing molecule makes some people adhere to stress better than others.
"Stress response is an important variable in vulnerability to alcohol dependence and other addictions, as well as other psychiatric disorders. This finding could help us understand individuals' initial vulnerability to these disorders," Nature quoted NIAAA Director Ting-Kai Li, M.D, as saying.
The researchers identified gene variants that affect the expression of the signalling molecule called neuropeptide Y (NPY), which is found in brain and many other tissues and also regulates many functions, like appetite, weight, and emotional responses.
"NPY is induced by stress and its release reduces anxiety. Previous studies have shown that genetic factors play an important role in mood and anxiety disorders. In this study, we sought to determine if genetic variants of NPY might contribute to the maladaptive stress responses that often underlie these disorders," said Dr. Goldman.
The researchers analysed human tissue samples and identified several NPY gene variants and showed that they lead to many effects, like altered levels of NPY in brain and other tissues, and differences in emotion and emotion-induced responses of the brain.
By using functional brain imaging to evaluate NPY gene variants' effects on brain responses to stress and emotion, it was found that those who carry the variant having the lowest level of NPY reacted more emotionally to images of threatening facial expressions.
"Metabolic activity in brain regions involved in emotional processing increased when these individuals were presented with the threatening images," explained Dr. Goldman.
Another brain imaging experiment showed that people with the low level NPY variant were less tolerant to moderate levels of sustained muscular pain. Also, it is known that NPY's behavioural effects are carried out by interactions with opioid compounds produced by the body to help suppress pain, stress, and anxiety.
"As shown by brain imaging of opioid function, these individuals released less opioid neurotransmitter in response to muscle discomfort than did individuals with higher levels of NPY. Their emotional response to pain was also higher, showing the close tie between emotionality and resilience to pain and other negative stimuli," said Dr. Goldman.
Initial findings indicate that the low level NPY gene variant was more common than other variants among a small sample of individuals with anxiety disorders. Also, low-level NPY expression was found to be linked to high levels of trait anxiety.
"Trait anxiety is an indication of an individual's level of emotionality or worry under ordinary circumstances," explained Dr. Goldman.
It was concluded that these converging findings come in line with NPY's role as an anxiety-reducing peptide and also explain inter-individual variation in resiliency to stress.
The study's findings are reported in the latest issue of Nature.