Abstract: Objective To investigate the relationship between somatostatin and psoriasis. Methods The levels of somatostatin in the plasma and skin lesions of patients with psoriasis were determined by radioimmunoassay. The distribution of somatostatin in the skin lesions of 13 patients and eight normal skin samples was determined by ABC alkaline phosphatase immunohistochemical assay. The somatostatin mRNA expression was examined by in situ hybridization histochemistry. Results The plasma level of somatostatin of the patients was significantly lower than that in controls (P<0.05), whereas the concentration of somatostatin in the skin lesions was significantly higher than that in controls (P<0.05). The distribution of somatostatin was accumulated in patches in the papillary layer in three incipient cases. In 10 chronic cases with acute onset the distribution was the same as the normal controls, and scattered staining of somatostatin could be seen in the dermis. The three cases with strong positive staining of somatostatin were tested for the expression of somatostatin mRNA by in situ hybridization histochemistry. No signal of somatostatin mRNA expression was observed in any cells of the skin lesions. Conclusion The lower level of somatostatin in the plasma and high expression of somatostatin in the skin lesions suggest that somatostatin might play an important role in the pathogenesis of psoriasis.

Key words: Psoriasis, Somatostatin, RNA,messenger