Abstract
It has recently been confirmed that systemic administration of cortisone markedly inhibits the regeneration of connective tissues (1, 2), and also that this compound prevents the development of granulation tissues around turpentineinduced abscesses, when it is administered simultaneously with the provocative turpentine (3) . Hydrocortisone has independently reported to have a local effect of inhibition on tuberculin reaction, when this compound was previously administered under the skin, and similarly to show antiinflammatory effect on mosquito bits and chemical compound application (4, 5) . Fibroblast destruction by histamin injection is successfully prevented with combined administration of either one of cortisone or hydrocortisone, and, at the same time, polymorphonuclear leukocytes are suppressed to infiltrate into the histamin-produced foci (6) . Contrary to the antiphlogistic effect of gluco-corticoids, desoxycorticosterone, one of the most potent mineralo-corticoids, has been observed to have a stimulating effect on wound healing (7) . This evidence entirely agrees with the concept of prophlogistic mineralo-corticoids and antiphlogistic gluco-corticoids (8) . By a brilliant method to test granuloma-inducing effects of various irritants and of their combination with steroid hormones, it was found that desoxycorticosterone and Δ5-pregnenolone failed to inhibit inflammatory reaction with the similar dose to hydrocortisone (9) .
It is well evidenced that silica particles are markedly potent to develop local fibrosis when they are intraperitoneally and subcutaneously administered as well as inhaled through the respiratory tract. The latter mode of adminisration offers a serious problem on miner's silicosis. Therefore, the effect of steroid hormones on experimental silicosis strongly attracts our attention in order to obtain the final indication to human silicosis. When a finely ground quartz powder was introduced into the intraperitoneal cavity of animals combined with systemic treatment of cortisone, the fibrosis was inhibited in the mouse and depressed in the rat (10, 11) . However, there was no influence to the previously developed fibrosis (2, 12) . Although this fact is somewhat discouraging to secure a successful measure to prevent human silicosis, there is still left some probability to suppress its further development and more interest in connection with so-called“constitutional”participation in the aggression of silicosis. Along this line, we have examined the effect of four kinds of steroids available at present, namely, hydrocortisone, progesterone, estradiol and desoxycorticosterone, on the granulation tissue induced by silica dusts.
