Peripheral administration of antalarmin does not affect the HPA axis response. As described in Materials and methods, levels of corticosterone in serum were determined by RIA in the different groups of mice immediately after the last exposure to stress and on the 4th day of the interval that followed the last exposure to stress. Increased levels of corticosterone upon stress were not affected by the peripheral administration of antalarmin (A). Moreover, increased levels of corticosterone after the last exposure to stress were not affected by antalarmin either, and confirmed the development of chronic stress (B). Data are expressed as MEAN ± SEM. Five animals per group were used. * p < 0.05, compared to control not exposed to stress.