A research team led by WEI Zhengde and Prof. ZHANG Xiaochu from the University of Science and Technology of China of the Chinese Academy of Sciences revealed the neural mechanism of interaction between oxytocin (OXT) and nicotine addiction in stress relief with transcranial direct current stimulation (tDCS) experiment and functional magnetic resonance imaging (fMRI) techniques. The study was published in Translational Psychiatry.

OXT, a neuropeptide well-known for its anxiolytic properties, can alleviate both subjective stress levels and neuroendocrine stress responses in healthy individuals. However, smokers experience a diminished response to OXT’s stress-relief effects. Therefore, there is an urgent need to explore the connection between OXT and nicotine-addicted individuals.

In this study, the researchers conducted an experiment using tDCS and fMRI to evaluate OXT’s impact on stress in both healthy controls and smokers. It was shown that while OXT significantly reduced stress scores and salivary cortisol levels (the stress hormone) in the control group, the same effects were not observed in smokers.

To investigate potential ways to restore OXT’s stress-reducing efficacy in smokers, the researchers applied tDCS to the anterior superior temporal gyrus (anterior rSTG) which plays a key role in processing social and emotional information. After stimulation, smokers showed a significant reduction in stress scores and salivary cortisol levels, indicating that tDCS may help recover their sensitivity to OXT’s effects.

Furthermore, utilizing psychophysiological interaction (PPI) analysis, the researchers revealed that OXT treatment weakened the functional connectivity between the anterior rSTG and the right middle frontal gyrus (rMFG). Notably, tDCS stimulation improved this connectivity, thereby enhancing OXT's anxiolytic impact.

This study highlights the weakened stress-relieving effect of OXT in smokers, paving the way for developing new anti-stress interventions for smokers.