The mechanism of the anti-inflammatory effect of turpentine in the rat.

The influence of counter irritation by turpentine on carrageenan-oedema, leucocyte count, plasma kininogen stores and composition of sponge-induced exudates has been investigated in the rat. Counter irritation reduced the carrageenan-oedema in normal as well as in adrenalectomized rats. It induced leucopenia with lymphopenia but did not modify the plasma kininogen stores. In turpentine-pretreated rats, the exudates induced by sponge implantation 18 h previously had a lower content in leucocytes. Their levels in beta-glucuronidase and beta-galactosidase were slightly reduced, their content in PGE2 was not modified and their level in malonaldehyde was increased. The exudates induced by sponge implantation 4 h previously had a lower content in leucocytes and PGE2 while their level in kinins was not modified. The mechanism of the anti-inflammatory effect of counter irritation by turpentine is discussed. We suggest that the main factor involved is a decrease in leucocyte accumulation into the exudates.