Blood purine and energy status in rats with colitis

Huang Qi Jian Zhong Pellet Attenuates TNBS-Induced Colitis in Rats via Mechanisms Involving Improvement of Energy Metabolism

Huang Qi Jian Zhong Pellet (HQJZ) is a famous Chinese medicine formula for treatment of various gastrointestinal tract diseases. This study investigated the role of HQJZ in 2,4,6-trinitrobenzene sulfonic acid- (TNBS-) induced colitis and its underlying mechanism. Colonic mucosal injury was induced by TNBS in the Sprague-Dawley rats. In the HQJZ treatment group, HQJZ was administered (2 g/kg) for 14 days starting from day 1 after TNBS infusion. Colonic mucosal injury occurred obviously 1 day after TNBS challenge and did not recover distinctively until day 15, including an increase in macro- and microscopic scores, a colonic weight index, a decrease in colonic length, a number of functional capillaries, and blood flow. Inverted intravital microscopy and ELISA showed colonic microcirculatory disturbances and inflammatory responses after TNBS stimulation, respectively. TNBS decreased occludin, RhoA, and ROCK-I, while increasing Rac-1, PAK-1, and phosphorylated myosin light chain. In addition, ATP content and ATP5D expression in colonic mucosa decreased after TNBS challenge. Impressively, treatment with HQJZ significantly attenuated all of the alterations evoked by TNBS, promoting the recovery of colonic injury. The present study demonstrated HQJZ as a multitargeting management for colonic mucosal injury, which set in motion mechanisms involving improvement of energy metabolism.

HPLC assay with UV detection for determination of RBC purine nucleotide concentrations and application for biomarker study in vivo

ATP and other purine nucleotides are important biomarkers for ischemia and may have considerable potential as targets for management of ischemic heart disease and stroke. The main objective of the study is to develop a rapid HPLC assay, which has adequate sensitivity and specificity for measuring concentrations of ATP, ADP, AMP, GTP, GDP and GMP in erythrocytes (RBC). The assays used ion-pair chromatography coupled with ultraviolet detection at 254 nm to separate and detect the purine nucleotides. Using 50-100 microL of RBC lysate as blank biologic matrix, the assay was linear from 100 to 2000 microg/mL for ATP and ADP, and 20-400 microg/mL for AMP, GTP, and GDP with coefficients of determination (r(2)) >0.99. GDP and GMP were not measurable in the study because of low concentrations and interference from endogenous materials, respectively. The intra-assay and inter-assay variations over a period of 1 year were less than 10% and 20%, respectively for most of the nucleotides. The assay was successfully applied to two pilot biomarker studies to measure RBC concentrations of the purine nucleotides in rats under restraining and exercise conditions. Preliminary results showed that the RBC concentrations of ATP and GTP were higher in the spontaneously hypertensive rats (SHR) compared to the Sprague-Dawley (SD) rats, and that exercise increased RBC concentrations of ATP in rats treated with the calcium channel blocker diltiazem.

Experimental colitis is associated with ultrastructural changes in inflamed and uninflamed regions of the gastrointestinal tract

OBJECTIVES

The objective of this study was to examine the ultrastructural changes in cell organelles such as mitochondria, endoplasmic reticulum (ER) and Golgi apparatus in inflamed colon and uninflamed ileum in colitic rats.

MATERIALS AND METHODS

Colitis was induced in rats by intracolonic administration of trinitrobenzenesulfonic acid (TNBS). The animals were sacrificed on day 5 after TNBS administration and colonic and ileal samples were used for estimation of myeloperoxidase (MPO) activity, malondialdehyde (MDA) concentration, histologic examination and transmission electron microscopy.

RESULTS

TNBS caused a significant reduction in body weight and an increase in MPO activity in colonic, but not in the ileal samples in animals with colitis. MDA levels were increased both in inflamed colon and the uninflamed ileal segments in colitis. Electron microscopy revealed swelling of mitochondria with broken cristae and disruption of the inner membrane. Colitis also caused fragmentation of the ER with loss of ribosomes and swelling of the Golgi apparatus with distended vesicles in both smooth muscle and epithelial cells in the ileal and colonic segments. These changes were absent in the control rats without colitis.

CONCLUSIONS

These findings demonstrate ultrastructural deformities in both the mucosa and smooth muscle in inflamed and uninflamed regions of the gastrointestinal tract in experimental colitis. The structural changes in mitochondria are responsible for reduced ATP, while abnormalities in the ER and the Golgi apparatus may explain a generalized effect on protein synthesis, trafficking and targeting mechanisms, and may account for physiological changes seen in experimental colitis.