Cold exposure increases intestinal paracellular permeability to nutrients in the mouse

Abstract

SUMMARYIn situations of increased energy demand and food intake, animals can often acclimate within several days. The intestine generally responds to elevated digestive demand by increasing in size. However, there is likely a limit to how quickly the intestine can grow to meet the new demand. We investigated the immediate and longer-term changes to intestinal properties of the mouse when suddenly exposed to 4°C. We hypothesized that paracellular permeability to nutrients would increase as part of an immediate response to elevated absorptive demand. We measured absorption of L-arabinose, intestinal size and gene expression of several tight junction proteins (claudin-2, claudin-4, claudin-15 and ZO-1) at three time points: pre-exposure, and after 1day and 2weeks of cold exposure. Cold exposure increased food intake by 62% after 2weeks but intake was not significantly increased after 1day. Intestinal wet mass was elevated after 1day and throughout the experiment. Absorption of arabinose rose by 20% after 1day in the cold and was 33% higher after 2weeks. Expression of claudin-2 increased after 1day of cold exposure, but there were no changes in expression of any claudin genes when normalized to ZO-1 expression. Our results indicate that intestinal mass can respond rapidly to increased energy demand and that increased paracellular permeability is also part of that response. Increased paracellular permeability may be a consequence of enterocyte hyperplasia, resulting in more tight junctions across which molecules can absorb.

Whey protein effects on energy balance link the intestinal mechanisms of energy absorption with adiposity and hypothalamic neuropeptide gene expression

“…The data suggest a signaling mechanism linking adiposity, hypothalamic neuropeptide gene expression, and intestinal growth, where the latter two changes may act to increase energy assimilation to counteract the energy loss in the adipose tissue. In fact, energy restriction, lactation, and cold exposure, each of which reduces adiposity and plasma leptin, also increased energy intake and the intestinal weight (8,30,40,46). By changing the protein to WPI, and bearing in mind the effect on the intestinal mechanisms of energy absorption and presumed energy loss, the above effects of the low sucrose were accentuated.…”

Ways to be different: foraging adaptations that facilitate higher intake rates in a northerly-wintering shorebird compared to a low-latitude conspecific

“…These differences were interpreted as a flexible phenotypic response to the higher rates of food intake necessary to satisfy the higher energetic demands of wintering in Norway (Summers et al, 1998). Such phenotypic changes in gut morphology and function are well documented in many species in response to a variety of environmental and lifehistory stimuli (Clissold et al, 2013;Dykstra and Karasov, 1992;Price et al, 2013;Starck, 1999). However, given the identical holding conditions of our experimental setup, differences between the subspecies noted here probably represent intrinsic adaptations rather than phenotypic responses.…”

Digestive Adaptations of Aerial Lifestyles

“…We have since extended our measurements to include more birds, several bat species, other small nonflying mammals, and a lizard (12,14,27,28,67,75,76,78,87,88,107) (Price E, Karasov W, unpublished observations). In FIGURE 6A, we have plotted the 7 bats, 19 birds, 1 lizard, and 18 nonflying mammals for which we could find measurements of the fractional absorption of the following nutrient-sized probes: Diet was not a significant factor in either set.…”