Inflammatory effects of the tumor promoter croton-oil in BALB/c mice skin.

A single dose of 0.25% croton oil induced an edema when applied to the ears of BALB/c mice. The maximal edematous response resulted from a single application of 4% croton oil. At any dose level, edema maximized 6-7 h after croton oil application, waning thereafter to the control level by 30 h. When topically applied on the shaved back skin, a single dose of 0.25% croton oil induced an inflammatory effect characterized by epidermal hyperplasia and infiltration of polymorphonuclear leucocytes (PMNs) in the dermis. Higher doses of croton oil caused more remarkable inflammatory response. The histological changes which were slightly detected in the skin 4 h after application of croton oil, reached a maximal level by 20-27 h, but substantially subsided by 72 h. Results proved that the tumor-promoter croton oil induces an inflammation in mice skin in a dose- and time-dependent process.