Alleviation by gamma amino butyric acid supplementation of chronic heat stress-induced degenerative changes in jejunum in commercial broiler chickens.

High ambient temperature adversely influences poultry production. In the present study, gamma amino butyric acid (GABA) supplementation was used to alleviate the adverse changes due to heat stress (HS) in a broiler chicken strain (Ross 308). At 21 days of age, the birds were divided into four groups of 13. Two groups were housed under normal room temperature, one group was given orally 0.2 ml 0.9% physiological saline (CN) daily, the other group received 0.2 ml of 0.5% GABA solution orally (GN). A third group was exposed to environmental HS (33 ± 1 °C lasting for 2 weeks) + physiological saline (CH) and a fourth group was exposed to HS + GABA supplementation (GH). GABA supplementation during HS significantly reduced the birds' increased body temperature (p <.0001) and increased their body weight gain (p <.0001). This effect was associated with increases in the heat stress-induced reductions in jejunal villus length, crypt depth and mucous membrane thickness, and decreases in the vascular changes occurred due to HS. Additionally, GABA supplementation significantly modulated HS-induced changes in glucose facilitated transporter 2 (GLUT2), peptide transporter 1 (PEPT1) and heat shock protein 70 (HSP70) mRNA expression in the jejunal mucosa (p < .0001). GABA supplementation also significantly elevated the triiodothyronine (T3) hormone level and hemoglobin levels and decreased the heterophil-lymphocyte ratio (H/L ratio) (p <.0001). Furthermore, it induced higher hepatic glutathione peroxidase enzyme (GSH-Px) activities and decreased the malondialdehyde dehydrogenase (MDA) content. These results indicate that GABA supplementation during HS may be used to alleviate HS-related changes in broiler chickens.

Effect of Curcuma comosa extracts on the functions of peptide transporter and P-glycoprotein in intestinal epithelial cells.

Curcuma comosa has been widely used as a herbal medicine in Thailand; however, it remains unclear whether C. comosa influences the absorption of drugs that are substrates for the transporters in the small intestine. In this study, we investigated the effect of C. comosa extracts on the functioning of peptide transporter 1 (PEPT1), an influx transporter, and P-glycoprotein (P-gp), an efflux transporter, in Caco-2 cells and rat intestine. In Caco-2 cells, the ethanolic extract of C. comosa (CCE) lowered the uptake of glycylsarcosine (Gly-Sar), a PEPT1 substrate, while it enhanced the uptake of rhodamine 123 (Rho123), a P-gp substrate, in a concentrationdependent manner. In addition, CCE inhibited apical-to-basal transport of Gly-Sar and basal-to-apical transport of Rho123. Furthermore, the absorption of cephalexin, another PEPT1 substrate, and the exsorption of Rho123 across the rat intestine were inhibited by CCE. Conversely, CCW, the hot water extract of C. comosa, suppresses the function of PEPT1 but not of P-gp in Caco-2 cells. These results suggest that C. comosa used as a herbal medicine in Thailand may affect the intestinal absorption of certain drugs.