Immunohistochemical localization of aquaporin 4 (AQP4) in the porcine gastrointestinal tract

Abstract

The water channel aquaporin-4 (AQP4) is a protein widely expressed on plasma membrane of a variety of epithelial cells. In this study we investigated the expression of AQP4 in the gastrointestinal tract of the pig using immunohistochemical staining. We found no presence of AQP4 in the different regions of the pig stomach. In the porcine small intestine moderate immunoreactivity to AQP4 was detected in enterocytes (along the villi and in the bottom of the crypts), duodenal Brunner's glands and in enteric ganglia in cells lying in close vicinity to myenteric as well as submucous neurons. In superficial epithelial cells of the colonic mucosa as well as of caecal and colonic glands a very strong immunoreactivity to AQP4 was found. Both in the myenteric and submucous ganglia of the large intestine AQP4-positive cells surrounding enteric neurons were observed. We concluded that AQP4 expression in the porcine gastrointestinal tract showed some species-dependent differences in relation to other species. Based on the presented distribution pattern of AQP4, it is likely that the aquaporin plays a role in mucous (but not acid) secretion and intestinal absorptive processes in the pig. Aquaporins, gut, small intestine, large intestine, pig

Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines

“…In a microarray analysis, AQP4 mRNA has been detected in both the oxyntic and pyloric mucosa of weaned pigs, but with higher expression of AQP4 in the oxyntic mucosa related to hydrochloric acid and secretion when compared to that of pyloric mucosa [ 118 ]. Additionally, the cellular localization of AQP4 is not only distributed in porcine enterocytes along the villi and crypt in the small and large intestines, but also in its duodenal Brunner’s glands and enteric neurons by immunohistochemistry [ 119 ]. Moreover, AQP8 mRNA is present in both the mucosa of jejunum and ileum in weaned piglets [ 95 ].…”

Aquaporins in Health and Disease: An Overview Focusing on the Gut of Different Species

“…AQP4 was also found in the enterocytes along villi and in the Brunner glands [78,110,111] and revealed by Western blot analysis in the rat, guinea pig, mouse, and buffalo small intestine [78,104,109,110]. AQP4 mRNA expression was confirmed in the rat and buffalo small intestine [78,109].…”

“…AQP4-IR is distributed at the basolateral membrane of the cryptic cells located at the bottom of the crypt of the rat, guinea pig, buffalo, and porcine small intestine [ 10 , 78 , 110 , 111 ]. AQP4 was also found in the enterocytes along villi and in the Brunner glands [ 78 , 110 , 111 ] and revealed by Western blot analysis in the rat, guinea pig, mouse, and buffalo small intestine [ 78 , 104 , 109 , 110 ]. AQP4 mRNA expression was confirmed in the rat and buffalo small intestine [ 78 , 109 ].…”

“…AQP4-IR was localized on the basolateral membrane of epithelial cells isolated from the rat, buffalo, and porcine colon [ 53 , 79 , 111 , 119 ]. In addition, AQP4 expression was found in the endothelium and enteric neurons of the buffalo and rodent colon [ 79 , 119 ].…”

Effects of different dietary protein levels on intestinal aquaporins in weaned piglets

“…AQP4 is expressed mainly in the brain and is involved in the development of cerebral oedema and neuropsychiatric diseases (Filippidis et al, 2016). It is also closely related to chronic inflammation of the nasal mucosa and the retina (Arciszewski et al, 2015; Yaowu et al, 2012). The results of this experiment and some other studies (Arciszewski et al, 2015; Jiang et al, 2014) indicate that AQP4 is located in absorptive cells of villi in the jejunum and ileum and that AQP4 expression is downregulated in piglets with diarrhoea.…”