Immunohistochemical distribution of COX-1 and COX-2 in the renal tissue of pubere rats treated with capsaicin

The objective of this study was to investigate the effects of capsaicin on the renal distribution of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in pubere rats. The expression of the 2 enzymes was analyzed using immunohistochemistry in 50 days old rats daily treated with capsaicin (1 mg/kg, subcutaneously) diluted in 10% ethanol, 1% Tween 20 and 80% distilled water for one week, as well as in sham rats (only injected with the vehicle) and in not injected control rats (n = 10 in each group). Weight growth was significantly deleted in the treated rats but no kidney damage was evidenced by conventional histology. The COX-1 and COX-2 localisations were similar in all rats but the COX-2 expression intensity was markedly depressed in the proximal and distal tubules, macula densa and loops of Henle from the capsaicin treated rats whereas the COX-1 expression appeared increased in proximal tubules compared to the sham and control rodents. These results demonstrate that capsaicin which is already known to affect gastrointestinal, cardiovascular and respiratory systems, also interfere with the expression of cyclooxygenases in kidney in rats.