[Protective effect of catechin on renal microvessels in 5/6 nephrectomized rats and its mechanism]

To investigate the effects of catechin on angiotensin-converting enzyme (ACE) activity, angiotensin II(Ang II) content and microvessel density (MVD) in renal tissues of 5/6 nephrectomized rats.

Sixty SD rats were divided into 3 groups: sham-operated group, untreated group and catechin group. Animal model was reproduced by 5/6 nephrectomy. After 8- and 12-week administration, rats were sacrificed. Renal MVD was measured by immunohistochemical method with CD34 marking. Activities of ACE in plasma and renal cortices were measured by ultraviolet spectrophotometer, and Ang II contents in plasma and renal cortices were measured by radioimmunoassay. Glomerular sclerosis index (GSI) and tubule interstitial score (TIS) were calculated by semiquantitative integration with hematoxylin and eosin staining and periodic acid-Schiff staining.

After 8- and 12-week administration, the GSI and TIS in the catechin group were much less than those in the untreated group (P < 0.05, P < 0.01). MVDs around glomerulus and tubule at the end of the 8th and 12th week in the untreated group and the catechin group were much less than those in the sham-operated group (P < 0.01). The ACE activities and Ang II contents in plasma and renal cortices in the catechin group were much less than those in the untreated group (P < 0.01). By Pearson correlation analysis, we found that MVD had negative correlation with GSI, TIS, Ang II content, and ACE activity (P < 0.01), however, the ACE activity and Ang II content had positive correlation with GSI, TIS (P < 0.01).

Catechin can prevent the 5/6 nephrectomized rats from decreasing of MVD and inhibit the progress of glomerular sclerosis and interstitial fibrosis by inhibiting the activity of ACE and reducing the production of Ang II.