Abstract:

Objective To study the influence of emotion stress on mechanical hyperalgesia of masseter muscles in rats through the equipment of communication box. Methods 50 Sprague- Dawley rats were randomly divided into 5 groups: Control group, emtion stress（ES） group, drug control group, saline treated control group and footshock （FS） group, 10 rats each group. Footshock group only induced emotion stress and was not concerned with the result ofthe experiment. The last four groups of the rats were placed in communication box and bred under the same conditions during the experiment time. According to Rens′method, von Frey filaments were used to assess the muscle mechanical threshold, head withdrawal, leg raising and crying were observed as pain action. Results 1） During the adaptive period of 7 days before the emotion stress experiment, mechanical pain values of bilateral masseter muscles were descent and were stabilized in the 5 th to 7 th day. In emotion stress period, hyperalgesia of emotion stress group was induced in bilateral masseter muscles, and the peak time was the 7 th day, then it alleviated in the following days and was stabilized in the 12 th to 14 th day, but its pain threshold was lower than blank control group. 2）During the emotion stress period, the change of drug control group was similiar to stress group but its pain threshold was higher. Conclusion It is suggested that emotion stress can lead to the hyperalgesia of masseter muscles and antidepressant drug can lower the hyperalgsia resulted of emotion stress.

Key words: emotion stress, masseter muscles, hyperalgesia