Methods: Male Wister rats aged eight weeks (n=35) were divided into two groups: control (n=15) and experimental (n=20). When restraint stress was applied to the experimental group, the muscle activity of BLA was recorded and blood samples were taken after 6 hours. Levels of catecholamine, cortisol, corticosterone and neutrophil/lymphocyte ratio were measured. Additionally, the stomach was removed and the damage level of the mucous membrane was evaluated.
Results: Experimental group showed significant increase in the physiological parameters measured compared with the control group. Furthermore, there was a significant negative correlation between these parameters and the BLA time. Also, significant correlations were found between catecholamine and neutrophil and between cortisol and lymphocyte. The proportion of neutrophil to lymphocytes in blood leukocytes inversed at the end of restraint stress and was sustained until the end of the trial.
Conclusions: These results indicate that activity of the masticatory organ plays an important allostatic role in mitigating effects produced by stress.
This work was supported by an Open Research Center subsidy (H18) from MEXT.