The expression of glycogen synthase in the small intestine of untreated STZ-induced diabetic rats was significantly (p<0.05) decreased by comparison with those of the non-diabetic control rats after the 5-week experimental period. Interestingly, treatment of STZ-induced diabetic rats with OA and MA significantly (p<0.05) increased the expression of glycogen synthase in the small intestine. Similarly, rats treated with the standard anti-diabetic drugs, metformin and insulin showed significant (p<0.05) increases in the intestinal expression of glycogen synthase after the 5-week period (see Figure 24).
85
0 1 2 3 4
ND DC OA MA MET INS
D e n si ty G ly co g e n s y n th a se/ -a c ti n
Figure 24. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on small intestine glycogen synthase expression with untreated STZ- diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.
86 3.9.2 α-amylase and α-glucosidase
The small intestine α-amylase and α-glucosidase expression of untreated STZ-induced diabetic rats were significantly (p<0.05) increased by comparison with those of the non-diabetic control rats after the 5-week experimental period. However, treatment of STZ-induced diabetic rats with OA and MA significantly (p<0.05) decreased the intestinal expression these carbohydrate hydrolyzing enzymes. STZ-diabetic rats treated with standard drugs metformin and insulin showed a similar response pattern of results (see Figure 25 and Figure 26).
87
ND DC OA MA MET INS
0 1 2 3
D en si ty ( -a m y la se/ -a c ti n )
Figure 25. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on small intestine α-amylase expression with untreated STZ-diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.
88
ND DC OA MA MET INS
0 1 2 3
D en si ty ( -g lu co si d a se / -a ct in )
Figure 26. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on small intestine α-glucosidase expression with untreated STZ- diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.
89 3.9.3 SGLT1 and GLUT2
The small intestine expression of SGLT1 and GLUT2 in STZ-induced diabetic rats were significantly (p<0.05) increased by comparison with those of the non-diabetic rats after the 5- week experimental period. On the other hand, treatment of STZ-induced diabetic rats with OA and MA significantly (p<0.05) decreased the intestinal expressions of SGLT1 and GLUT2. STZ- diabetic rats treated with standard drugs metformin and insulin showed a similar response pattern of results (see Figure 27 and Figure 28).
90
ND DC OA MA MET INS
0 2 4 6 8
Den si ty ( S G L T1 / -a ct in )
Figure 27. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on small intestine SGLT1 expression with untreated STZ-diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.
91
ND DC OA MA MET INS
0.0 0.5 1.0 1.5 2.0 2.5
De n si ty ( G LU T 2 / -a c ti n )
Figure 28. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on small intestine GLUT2 expression with untreated STZ-diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.
92 3.9.4 Ghrelin
The expression of ghrelin in the gastric fundus, small and large intestine of STZ-induced diabetic rats was significantly (p<0.05) increased by comparison with those of the non-diabetic rats after the 5-week experimental period. On the other hand, treatment of STZ-induced diabetic rats with OA and MA significantly (p<0.05) decreased the expression of ghrelin in the gastric fundus as well as in the small and large intestine. Additionally, STZ-diabetic rats treated with standard drugs metformin and insulin showed a similar response pattern of results (see Figure 29, Figure 30 and Figure 31).
93
0 4 8 12
ND DC OA MA MET INS
D en si ty ( G h rel in / -a ct in )
Figure 29. Comparison of the effects of OA and MA administered in STZ-diabetic rats twice every third day for 5 weeks on gastric fundus ghrelin expression with untreated STZ-diabetic rats and those treated with the standard drugs metformin and insulin. Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each group).♦=p<0.05 by comparison to the non-diabetic control. =p<0.05 by comparison to the STZ-induced diabetic control.