Daily expression modulation of SGLT1 in rat jejunum during ontogeny

BASTÓN, J. I.; CHEDIACK, J. G.; CID, F. D.; KARASOV, W.; CAVIEDES-VIDAL E.

Boston, Massachusetts, United States

Congreso; SICB (Society for Integrative and Comparative Biology) Anual Meeting; 2009

Society for Integrative and Comparative Biology

SGLT1, the small intestine apical membrane protein responsible for active glucoseabsorption, exhibits a daily pattern of activity and protein and mRNA expression in adultrats. The activity and expression of SGLT1 is higher during dark periods when the rats areactive and feeding than during light periods when they rest. However, rats during postnatalgrowth feed throughout the day and they have increasing nutrient requirements. Thus, wecharacterized the daily expression modulation of SGLT1 protein in rat jejunum at differentages. Using western blots (WB) we semi-quantified SGLT1 relative to alpha-actin in jejunalhomogenates collected at 3:00h, 9:00h, 15:00h and 21:00h from 14d, 21d, 28d and 90d oldSprague-Dawley rats (ad-libitum water and food; light on schedule: 6h-18h). Immunoreactivebands (with MW compatible with different degrees of glycosylation of the SGLT1monomer, and the tetramer) for each jejunum sample were summed and normalized toalpha-actin for analyses. SGLT1 expression pattern between ages was: 14d <21d=28d, andtended to decrease at 90d. Within ages, only 90d rats exhibited a clear daily expressionrhythm. SGLT1 was lowest at 9:00h and then rose to reach a peak at 21:00 [statisticaldifferences (p <0.05): 9:00h < 15:00h = 21:00h = 3:00h]. In summary, SGLT1 proteinexpression increases with age reaching maxima during weaning and post-weaning periods.A daily pattern of expression was apparent only in young adult rats (90d old). This patternmatches previous observation of a continuous feeding during the day to supply nutrients tocope with the high energy requirements of growth. Supported by PICT2004 25561,CyT-UNSL 22Q751 to ECV, NSF IOS0615678 to WHK.