Published online Sep 28, 2017. doi: 10.3748/wjg.v23.i36.6650
Peer-review started: March 23, 2017
First decision: April 28, 2017
Revised: July 14, 2017
Accepted: July 22, 2017
Article in press: July 22, 2017
Published online: September 28, 2017
To determine whether oral glutathione (GSH) administration can alleviate the effects of fasting-induced intestinal atrophy in the small intestinal mucosa.
Rats were divided into eight groups. One group was fed ad libitum, another was fed ad libitum and received oral GSH, and six groups were administrated saline (SA) or GSH orally during fasting. Mucosal height, apoptosis, and cell proliferation in the jejunum were histologically evaluated. iNOS protein expression (by immunohistochemistry), nitrite levels (by high performance liquid chromatography, as a measure of NO production), 8-hydroxydeoxyguanosine formation (by ELISA, indicating ROS levels), glutathione/oxidized glutathione (GSH/GSSG) ratio (by enzymatic colorimetric detection), and γ-glutamyl transpeptidase (Ggt1) mRNA levels in the jejunum (by semi-quantitative RT-PCR) were also estimated.
Oral GSH administration was demonstrated to drastically reduce fasting-induced intestinal atrophy in the jejunum. In particular, jejunal mucosal height was enhanced in GSH-treated animals compared to SA-treated animals [527.2 ± 6.9 for 50 mg/kg GSH, 567.6 ± 5.4 for 500 mg/kg GSH vs 483.1 ± 4.9 (μm), P < 0.01 at 72 h]. This effect was consistent with decreasing changes in GSH-treated animals compared to SA-treated animals for iNOS protein staining [0.337 ± 0.016 for 50 mg/kg GSH, 0.317 ± 0.017 for 500 mg/kg GSH vs 0.430 ± 0.023 (area of staining part/area of tissue), P < 0.01 at 72 h] and NO [2.99 ± 0.29 for 50 mg/kg GSH, 2.88 ± 0.19 for 500 mg/kg GSH vs 5.34 ± 0.35 (nmol/g tissue), P < 0.01 at 72 h] and ROS [3.92 ± 0.46 for 50 mg/kg GSH, 4.58 ± 0.29 for 500 mg/kg GSH vs 6.42 ± 0.52 (8-OHdG pg/μg DNA), P < 0.01, P < 0.05 at 72 h, respectively] levels as apoptosis mediators in the jejunum. Furthermore, oral GSH administration attenuated cell proliferation decreases in the fasting jejunum [182.5 ± 1.9 for 500 mg/kg GSH vs 155.8 ± 3.4 (5-BrdU positive cells/10 crypts), P < 0.01 at 72 h]. Notably, both GSH concentration and Ggt1 mRNA expression in the jejunum were also attenuated in rats following oral administration of GSH during fasting as compared with fasting alone [0.45 ± 0.12 vs 0.97 ± 0.06 (nmol/mg tissue), P < 0.01; 1.01 ± 0.11 vs 2.79 ± 0.39 (Ggt1 mRNA/Gapdh mRNA), P < 0.01 for 500 mg/kg GSH at 48 h, respectively].
Oral GSH administration during fasting enhances jejunal regenerative potential to minimize intestinal mucosal atrophy by diminishing fasting-mediated ROS generation and enterocyte apoptosis and enhancing cell proliferation.
Core tip: We have previously demonstrated that the intestinal mucosal atrophy consequent to fasting is due in large part to increased apoptosis in jejunal villi and decreased cell proliferation in jejunal crypts, with concomitant increased reactive oxygen species (ROS) and NO production and decreased glutathione (GSH). Here we demonstrate protection against fasting-induced intestinal mucosal atrophy by minimizing ROS induction in the intestinal mucosa through supplemental oral administration of an antioxidant such as GSH during fasting in rats. In particular, oral GSH administration during fasting enhances jejunal regenerative potential by diminishing enterocyte apoptosis and enhancing cell proliferation.