SKIN WOUND-HEALING - SOME BIOCHEMICAL PARAMETERS IN GUINEA-PIG

Hairs were removed from the dorsal skin of guinea-pigs and 5 6 wounds (7 x 7 mm) were surgically induced by totally removing the epidermal a nd part of the dermal surface. They were then allowed to heal. The new ly formed wound tissues were dissected at different times during the p rocess and analysed by biochemical and histological methods. Hydroxypr oline, proteins, DNA and semicarbazide-sensitive amine oxidase (SSAO) were measured, as were [C-14]leucine and [H-3]thymidine incorporation in some samples. The peroxidase-like activity of plasma albumin and th e histology of wounds stained with haematoxylin-eosin were also studie d. It was shown that SSAO enzymes, which are present in normal guinea- pig skin and have a high affinity for benzylamine are localized in fib roblasts. During skin healing in the newly formed tissue there was an increase in protein content which reached a maximum after 4-6 days; DN A content also increased. The rate of incorporation of [H-3]thymidine and [C-14]leucine paralleled DNA and protein content, respectively. Th e content of hydroxyproline had greatly decreased with respect to that in normal skin after 210 days. SSAO activity increased much less than DNA after 4 days whereas after 10-11 days it increased more than DNA, thus indicating that at this time it was probably produced by fibrobl asts. No significant increase in the peroxidase-like activity of album in was observed 4, 8 or 11 days after surgery. Treatment of the animal s with methylprednisolone acetate (20 mg kg-1, i.m.) two days before s urgery decreased the rate of skin healing but did not alter the level of albumin peroxidase activity of the plasma. Histology showed that in the animals treated with this drug the re-epithelialization was slowe r and after 11 days the wound appeared similar in appearance to the 8- day control wounds. In the methylprednisolone-treated animals a positi ve correlation was observed between the DNA content of regenerating ti ssue and the hydroxyproline content, whereas a negative correlation wa s observed in the control wounds. This correlation was in full agreeme nt with the histological observation which showed an increased amount of cytogen collagen in the wounds of the treated animals. The simultan eous study of the biochemical parameters (DNA, proteins, SSAO, hydroxy proline) appears to be a good method for differentiating the pharmacol ogical effects on the different cells which are responsible for wound healing.