Objective The primary study has confirmed that moxibustion preconditioning （MP） had a protective action on rats with adjuvant arthritis （AA）. This paper investigated the protective mechanism of MP through an analysis of hypothalamic HSP70. Methods To observe the changes of hypothalamic HSP70 in AA rats before model established

at early stage and secondary stage after model established respectively by using immunohistochemistry

and to analyze these changes with image analysis technique. Results The expression of hypothalamic HSP70 was limited positive in the normal group

and that in AA group of early stage and secondary stage was strong positive compared with the normal group

but had a decreasing trend along with the disease course. In the groups with MP the abnormal high expressions of hypothalamic HSP70 were relived not only at early stage but also at secondary stage compared with AA group. MP also improved the expression of hypothalamic HSP70 in normal rats. Conclusion The protective action of MP on AA rats may be related to that it can improve the positive expression of hypothalamic HSP70 in normal rats

and decreases obviously the abnormal high expression of hypothalamic HSP70 in AA rats. Hypothalamic HSP70 may be one of important factors for MP actions of preventing and relieving the disease and strengthening the constitution.