Daily expression modulation of SGLT1 in rat jejunum during ontogeny

BASTÓN, JI; CHEDIACK, JG; CID, FD; CAVIEDES-VIDAL E; KARASOV, WH

Boston - USA

Congreso; Annual Meeting of the Society for Integrative and Comparative Biology; 2009

Society for Integrative and Comparative Biology

SGLT1, the small intestine apical membrane protein responsible for active glucose absorption, exhibits a daily pattern of activity and protein and mRNA expression in adult rats. The activity and expression of SGLT1 is higher during dark periods when the rats are active and feeding than during light periods when they rest. However, rats during postnatal growth feed throughout the day and they have increasing nutrient requirements. Thus, we characterized the daily expression modulation of SGLT1 protein in rat jejunum at different ages. Using western blots (WB) we semi-quantified SGLT1 relative to alpha-actin in jejunal homogenates collected at 3:00h, 9:00h, 15:00h and 21:00h from 14d, 21d, 28d and 90d old Sprague-Dawley rats (ad-libitum water and food; light on schedule: 6h-18h). Immuno-reactive bands (with MW compatible with different degrees of glycosylation of the SGLT1 monomer, and the tetramer) for each jejunum sample were summed and normalized to alpha-actin for analyses. SGLT1 expression pattern between ages was: 14d <21d=28d, and tended to decrease at 90d. Within ages, only 90d rats exhibited a clear daily expression rhythm. SGLT1 was lowest at 9:00h and then rose to reach a peak at 21:00 [statistical differences (p <0.05): 9:00h < 15:00h = 21:00h = 3:00h]. In summary, SGLT1 protein expression 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 pattern matches previous observation of a continuous feeding during the day to supply nutrients to cope with the high energy requirements of growth. Supported by PICT2004 25561, CyT-UNSL 22Q751 to ECV, NSF IOS0615678 to WHK.