The Absorption and Transportation of Glutamine Containing Small Peptides-Arg-Gly-GIn and Gly-GIn in Jejunum of Weaned Piglets

In order to research the absorption and transportation differences ofglutamine containing small peptides and free glutamine in intestine of weaned piglets, 28-day-old weaned piglets were selected to get the sample for jejunum culture in vitro in this study. Trial 1 was conducted to study the stability of tripeptide （Arg-Gly-Gln） in the jejunum to determine the ideal culture time. It was designed into 2 treatments： control group （Kreb＇s solution, GC） and tripeptide group （by adding 556μmol/L of Arg-Gly-Gln to Kreb＇s solution, GP）. They were cultured for 60 min. The absorption and transportation differences ofglutamine existing as Arg-Gly-Gln, Gly-Gln and free Gin were studied in trial 2. It was designed into 4 treatments： group 1 （G1, control group）, Kreb＇s solution; Group 2 （G2）, Kreb＇s solution＋556 μmol/L Arg-Gly-Gln; group 3 （G3）, Kreb＇s solution＋556 μmol/L Gly-Gln and Arg; group 4 （G4）, Kreb＇s solution＋556 μmol/L arginine, glycine and glutamine. They were cultured for 40 minutes. The results indicated that the absorption and transportation of glutamine existing as Arg-Gly-Gln was more efficient than those of Gly-Gln while Gly-Gln was more efficient than free glutamine. Arg-Gly-Gln may be more excellent than Gly-Gln in physiological functions and nutrition potential.

Carotenoids in Aquaculture:An Overview

Recent studies on the role of carotenoids in aquaculture have investigated their function in regulating pigmentation, growth, survival, and immune activity of aquatic animals. These carotenoids include astaxanthin, canthaxanthin, lutein, zeaxanthin, and tunaxanthin. Astaxanthin and canthaxanthin are the main synthetic carotenoids used world-wide in the aquaculture industry. They play an important role in protecting cells and organisms against photosensitized oxidations. Direct evidence of carotenoids functioning as antioxidants in vivo has been reported in animal models. In addition to their established biological effects as antioxidants, carotenoids appear to have a great variety of cellular actions that make them remarkable physiological modulators. Consequently, recent attention has been focused on improving our understanding of carotenoids on the physiology and metabolism in aquatic animals with a view to enhance the efficacy of astaxanthin as a carotenoid pigment. This review aims to summarize the function and research progress of carotenoids in aquaculture. We discuss the methods used to study the absorption, transport, metabolic transformation and deposition of carotenoids, and their spatial and temporal expression.

Studies on Absorption and Tansport of Limoninoids from Fructus Evodiae in Caco-2 Cell Monolayer Model

Objective To study the intestinal absorption and transepithelial transport of three limoninoids: evodol (EVO), limonin (LIM), and shihulimonin A (SHIA), isolated from Fructus Evodiae [the unripe fruit of Evodia rutaecarpa and Evodia rutaecarpa var. bodinieri] in the human intestine. Methods The in vitro cultured human colon carcinoma cell line, Caco-2 cell monolayer model, was applied to studying the absorption and transepithelial transport of the three limoninoids from apical (AP) to basolateral (BL) side and from BL to AP side. The three limoninoids were measured by reversed-phase high performance liquid chromatography coupled with ultraviolet absorption detector. Transport parameters and apparent permeability coefficients (Papp) were then calculated and compared with those of Propranolol as a control substance of high permeability and Atenolol as a control substance of poor permeability. Results The Papp value of EVO and LIM from AP to BL side for absorption and transport were 1.78 × 10-5 cm/s and 1.16 × 10-5 cm/s, respectively, which was comparable to that of Propranolol with Papp 2.18 × 10-5 cm/s. Conclusion The absorption and transport of both EVO and LIM are main passive diffusion as the dominating process in Caco-2 cell monolayer model, and they were estimated to be high absorbed compounds. SHIA in Caco-2 cell monolayer model may be involved in metabolism in the transport processes.

Lanthanum chloride or citrate is absorbed mainly via M cells in gastrointestinal tracts with lanthanum phosphates as the transformed species

In the present study, we investigated the transformed species and the absorptive mechanism of rare earth elements（REEs） in gastrointestinal（GI） tract, using La Cl3 and La Cit as representative compounds. Artificial gastric and intestinal fluids were used to simulate the environment of the digestive tract in vivo. The inductively coupled plasma mass spectrometry（ICP-MS） result showed that more than 99.9% of La Cl3 and La Cit formed precipitation in artificial intestinal fluid, with the average size distribution of 200 nm（2-h incubation） increasing to 600 nm（24-h incubation） determined by dynamic light scattering（DLS）, indicating the aggregation of the particles. The Fourier transform infrared spectroscopy（FTIR） analysis demonstrated that the constituents of these particles were mainly in the form of lanthanum phosphates. To explore the transport mechanism of REEs in GI tract, the mice Peyer＇s patches（PPs） and intestinal epithelium were separated to evaluate the content of lanthanum by ICP-MS following oral administration with 2 or 100 mg/kg/day of La Cit for 7 d. The results showed that the amount of lanthanum phosphate particles absorbed by PPs was significantly greater than that of intestinal epithelium, indicating that lanthanum particles might be phagocytosed mainly by M cells located in the follicle-associated epithelium（FAE） overlying PPs. Furthermore, Caco-2 cell monoculture and Caco-2/Raji B cell coculture models were established to simulate intestinal epithelial cells and FAE, respectively. The result showed that the transport of lanthanum in Caco-2/Raji B coculture model was significantly higher than that in Caco-2 monoculture model（about 60 times higher）, and the level of lanthanum in the basal compartment of Caco-2 monoculture model was very low, supporting that M cells were the main route for lanthanum phosphate particles to be transported and absorbed. Taken together, these data suggested that La Cl3 and La Cit in GI tract were absorbed mainly via M cells with lanthanum phosphates as transformed species. The obtained results would provide the theoretical basis for the rational application of REEs in agriculture and medicine.