Jarinthorn Teerapornpuntakit. Changes in the expression of genes related to calcium transport in the intestine of endurance swimming female rats. Master's Degree(Exercise Physiology ). Mahidol University. : Mahidol University, 2008.
Changes in the expression of genes related to calcium transport in the intestine of endurance swimming female rats
Abstract:
Endurance exercise has been shown to increase the intestinal calcium absorption
in rats and humans. In contrast, immobilization, which is physical inactivity,
decreases intestinal calcium absorption. However, the molecular mechanism of these
effects is unknown. The present study therefore aimed to demonstrate the expression
profile of genes related to calcium transport in seven intestinal segments. In addition,
the effect of endurance swimming on the expression of those genes was investigated
in the intestine of female Sprague Dawley rats by using real-time PCR technique.
Animals were divided into 2-, 4-, and 8-week swimming groups, and 2-, 4-, and 8-
week age-matched sedentary controls.
The results showed that the highest expression of TRPV6, PMCA1b, calbindin-
D9k, ZO-1, ZO-2, occludin, and cingulin were found in the cecum. Endurance
swimming mostly increased expression of the transcellular genes in the small
intestine, especially in the duodenum. Paracellular genes, i.e., ZO-1, ZO-2, ZO-3,
occludin, cingulin, and claudin-3 were upregulated in the duodenum of 2-week
swimming rats. Interestingly, such response seemed to be diminished after prolonged
training. More distal intestine (e.g., proximal colon and distal colon) had a tendency
to decrease expression of ZO-1, ZO-2, ZO-3, occludin, cingulin, and claudin-3 after
2 weeks of swimming. Nevertheless, after 4-8 weeks of swimming, expression of
ZO-1, ZO-2, ZO-3, occludin, cingulin, and claudin-3 in the proximal colon were
dramatically upregulated, whereas those in the cecum and distal colon were
downregulated. The expression of VDR was also increased in the small intestine.
Finally, microarray study demonstrated that the expression of several intestinal genes
e.g., Clcnkb, P2ry6, Kcnab2, Tlr4, and Nov was altered after swimming, suggesting
that endurance exercise induced a profound adaptive change in the intestine at the
molecular level.
It could be concluded that the region of high calcium absorption, i.e. small
intestine and cecum, strongly expressed genes related to intestinal calcium transport.
Positive effects of swimming on both transcellular and paracellular genes expression
were seen in the small intestine where most calcium absorption occurs, whereas it
produced less effect on the large intestine. In other words the large intestine was less
sensitive to endurance swimming than the small intestine.