Progesterone metabolism by rat oral mucosa. III. Participation of granulation tissue and fibroblasts

The metabolism of progesterone by rat granulation tissue was studied. Experimental granulation tissue was produced by implanting viscose‐cellulose sponges beneath the dorsal skin of female and male rats for 21 days. The granuloma capsules and fibroblasts in the sponges were homogenized, and mitochondrial, microsomal and soluble fractions were prepared with differential centrifugation. The subcellular Preparations were incubated with 4‐14C‐progesterone and NADPH for 30 min at PH 7.4 and 37°C. The metabolites were identified with column and multiple thinlayer chromatography and radioautography and quantitated with liquid scintillation counting. The granulation tissue and fibroblasts showed much less activity in metabolizing progesterone than the gingival tissue of either sex. As reported earlier, gingival tissues contain Δ4‐5α‐ and,Δ4‐5β‐steroid hydrogenases and 3α‐, 3β‐, 20α‐ and 20β‐hydroxysteroid dehydrogenases. The granulation tissue and fibroblasts lack 3 β‐hydroxysteroid dehydrogenase activity. In addition, the fibroblasts show no 20 β‐hydroxysteroid dehydrogenase activity. The enhanced metabolism of progesterone during gingival inflammation is thus probably not due to the formation of granulation tissue.