The aim of this study was to evaluate the levels of disaccharidase and dipeptidyl peptidase IV activities in rat jejunal enterocytes under the influence of long-term germ-free conditions. We found that the brush-border lactase and dipeptidyl peptidase IV activities were two to three times higher in 2-month-old germ-free rats in comparison with their conventional counterparts. The highest effect of germ-free condition was observed on lactase activity in 6-month-old and dipeptidyl peptidase IV in 2-month-old rats. No difference between germ-free and conventional rats in sucrase and glucoamylase activities was found in 2-month-old rats. The difference develops with increasing age, sucrase activity becoming significantly higher in 6- and 12-month-old rats and glucoamylase in 12-month-old germ-free rats.
Quaternary benzo[c]phenanthridine alkaloids (QBA), fagaronine (FA), sanguinarine (SA), chelerythrine (CHE) and the QBA extract from Macleya cordata (EX) exerted differential inhibitory effect on the hydrolytic activity of particular dipeptidyl peptidase (DPP)-like enzyme isolated from human blood plasma and from human and rat glioma cell lines. The low-MW form of DPP-IV-like enzyme activity, corresponding most probably to DPP-8, observed only in glioma cells but not in human plasma, was inhibited preferentially by SA, CHE and EX, and only slightly by FA. The alkaloid inhibitory effect was concentration-dependent in the range 25-150 M and directly pH-related. In addition, a subtle but consistent inhibition of the intermediate-MW form of DPP-IV-like enzyme activity, ascribed to DPP-IV/CD26, observed only in human plasma and of the attractin (high-MW form of DPP-IV-like enzyme activity, expressed in U87 glioma cells) by the studied alkaloids was observed. We conclude that some of the QBA biological effects could be determined by tissue and cell type specific dipeptidyl peptidase IV-like molecules expression pattern., A. Šedo, R. Malík, J. Vičar, V. Šimánek, J. Ulrichová., and Obsahuje bibliografii