tailieunhanh - Báo cáo khoa học: Down-regulation of reduced folate carrier may result in folate malabsorption across intestinal brush border membrane during experimental alcoholism

Folate plays a critical role in maintaining normal metabolic, energy, differ-entiation and growth status of all mammalian cells. The intestinal folate uptake is tightly and diversely regulated, and disturbances in folate homeo-stasis are observed in alcoholism, attributable, in part, to intestinal mal-absorption of folate. | ỊFEBS Journal Down-regulation of reduced folate carrier may result in folate malabsorption across intestinal brush border membrane during experimental alcoholism Abid Hamid1 Nissar Ahmad Wani1 Satyavati Rana2 Kim Vaiphei3 Akhtar Mahmood4 and Jyotdeep Kaur1 1 Department of Biochemistry Postgraduate Institute of MedicalEducation and Research Chandigarh India 2 Department of Gastroenterology Postgraduate Institute of MedicalEducation and Research Chandigarh India 3 Department of Histopathology Postgraduate Institute of MedicalEducation and Research Chandigarh India 4 Department of Biochemistry Panjab University Chandigarh India Keywords alcoholism brush border membrane cryptvillus axis methylation reduced folate carrier Correspondence J. Kaur Department of Biochemistry Postgraduate Institute of MedicalEducation and Research Chandigarh 160 012 India Fax 91 172 2744401 2745078 Tel 91 172 2747585 5181 E-mail jyotdeep2001@ Received 1 August 2007 revised 6 October 2007 accepted 17 October 2007 doi Folate plays a critical role in maintaining normal metabolic energy differentiation and growth status of all mammalian cells. The intestinal folate uptake is tightly and diversely regulated and disturbances in folate homeostasis are observed in alcoholism attributable in part to intestinal malabsorption of folate. The aim of this study was to delineate the regulatory mechanisms of folate transport in intestinal absorptive epithelia in order to obtain insights into folate malabsorption in a rat model of alcoholism. The rats were fed 1 g-kg-1 body weight of ethanol daily for 3 months. A reduced uptake of 3H folic acid in intestinal brush border membrane was observed over the course of ethanol administration for 3 months. Folate transport exhibited saturable kinetics and the decreased intestinal brush border membrane folate transport in chronic alcoholism was associated with an increased Km value and a low Vmax value. Importantly the lower