Therapeutic effect of protease-activated receptor 2 agonist SLIGRL-NH₂ on loperamide-induced Sprague-Dawley rat constipation model and the related mechanism

Figures & data

Figure 1 Effect of SLIGRL-NH₂ on the expression of PAR-2 and c-kit in colons of loperamide-induced constipated rats.

Notes: (A) Relative mRNA expression of PAR-2 and c-kit in different groups by RT-qPCR. (B) Relative protein expression of PAR-2 and c-kit in different groups by Western blot. *p<0.05 versus constipation, **p<0.01 versus constipation, ***p<0.001 versus constipation.
Abbreviations: PAR-2, protease-activated receptor 2; RT-qPCR, real-time quantitative polymerase chain reaction.

Table 1 Effect of SLIGRL-NH₂ on the feeding behavior of rats in different groups (mean ± standard deviation)

Groups	Food intake (g/d)	Water intake (mL/d)
Control	19.23 ± 2.31	15.7 ± 2.21
Constipation	11.80 ± 1.92	11.2 ± 1.78
SLIGRL-NH2 low	12.28 ± 2.17	12.1 ± 1.93
SLIGRL-NH2 high	14.85 ± 2.25	13.2 ± 1.56*

Note:

* p<0.05 versus constipation group.

Table 2 Effect of SLIGRL-NH₂ on the excretion behavior of rats in different groups (mean ± standard deviation)

Groups	Fecal pellet number (n)	Fecal pellet weight (g)	Fecal water content (%)
Control	63.91 ± 8.39	0.53 ± 0.08	56.61 ± 2.91
Constipation	34.57 ± 6.87	0.29 ± 0.02	31.45 ± 2.13
SLIGRL-NH2 low	47.32 ± 7.58*	0.29 ± 0.04	49.72 ± 1.85*
SLIGRL-NH2 high	54.29 ± 9.31*	0.38 ± 0.05*	52.68 ± 1.46*

Note:

* p<0.05 versus constipation group.

Table 3 Effect of SLIGRL-NH₂ on the intestinal transit ratio of loperamide-induced constipated rats (mean ± standard deviation)

Groups	Intestinal length (cm)	Intestinal transit length (cm)	Intestinal transit ratio (%)
Control	114.13 ± 9.52	85.00 ± 6.12	74.56 ± 4.76
Constipation	103.67 ± 8.87	49.17 ± 3.54	47.43 ± 2.85
SLIGRL-NH2 low	95.57 ± 10.01	69.83 ± 2.96	73.05 ± 5.23*
SLIGRL-NH2 high	89.67 ± 7.24	68.19 ± 3.15	79.08 ± 6.74*

Note:

* p<0.05 versus constipation group.

Figure 2 Histological features of colons of rats in different groups with H&E staining.

Note: Magnification 200×; scale bar 100 uM.
Abbreviation: H&E, hematoxylin and eosin.

Table 4 Effect of SLIGRL-NH₂ on the histological features of loperamide-induced constipated rats (mean ± standard deviation)

Groups	Thickness of the mucosa layer (μm)	Number of goblet cells (ea)	Number of enterocytes (ea)
Control	401 ± 37.8	87.2 ± 8.2	124.1 ± 9.5
Constipation	125 ± 13.7	52.3 ± 4.1	79.6 ± 8.5
SLIGRL-NH2 low	274 ± 25.3*	60.6 ± 4.9	90.1 ± 9.2
SLIGRL-NH2 high	385 ± 39.2**	79.5 ± 7.3**	118.5 ± 9.7*
Prucalopride	411 ± 29.3**	82.4 ± 9.1**	116.4 ± 8.9*

Notes:

* p<0.05,

** p<0.01 versus constipation group. “ea” indicates that the microscope image observed at 200×.

Figure 3 Effect of SLIGRL-NH₂ on the expression of ANO1 in colons of loperamide-induced constipated rats.

Notes: Magnification 200×. Scale bar = 100 μM.
Abbreviations: PAR-2, protease-activated receptor 2; ANO1, anoctamin-1.

Figure 4 Effect of SLIGRL-NH₂ on the expression of VIP and SP in colons of loperamide-induced constipated rats.

Notes: (A) Relative expression of VIP in different groups by ELISA. (B) Relative protein expression of SP in different groups by ELISA. *p<0.05 versus constipation, **p<0.01 versus constipation.
Abbreviations: ELISA, enzyme-linked immunosorbent assay; SP, substance P; VIP, vasoactive intestinal peptide.