Age dependency of cyclosporin A-induced gingival overgrowth in rats.

Effects of age on cyclosporin A- (CsA) induced gingival overgrowth were investigated in Fischer rats. Rats 15, 30, 45, and 60 days old were fed a diet containing cyclosporin A (120-200 micrograms/g) for 40 days. Gingival overgrowth was estimated by measuring the gingival sulcus depth with a thin color slide probe under a stereoscopic dissecting microscope. The youngest group (15 days old) of rats developed the most significant gingival overgrowth (buccal sulcus depth of mandibular first molar, CsA-treated rat/untreated rat: 875 +/- 78/275 +/- 25 micron, mean +/- SD, P < 0.001), followed by those in which CsA treatment was initiated at age 30 days (505 +/- 29/267 +/- 56, P < 0.001) and 45 days (400 +/- 45/267 +/- 25, P < 0.001). Significant gingival overgrowth was not induced in rats when CsA treatment had been started at age 60 days (310 +/- 38/292 +/- 18). Average body weight gain of CsA-treated rats during this experiment period was not different from untreated rats of the same age group. These results suggest that CsA-induced gingival overgrowth in rats is age dependent.