Dynamic changes in basal lamina fenestrations in rat intestinal villous epithelium under high-fat diet condition

Abstract

The basal lamina of the villous epithelium in the small intestine has numerous fenestrations, which are produced by leukocytes for their intraepithelial migration. We previously showed that these fenestrations change due to the dynamics of migrating leukocytes in response to dietary conditions and suggested the possibility that this change is related to the regulation of the absorption of large-sized nutrients such as chylomicrons. The present study was, thus, designed to investigate structural changes in basal lamina fenestrations in response to a high-fat diet. The ultrastructure of the intestinal villi in the rat upper jejunum was investigated by electron microscopy of tissue sections in both the normal and the high-fat diet groups, and the fenestrations in the villous epithelium of rat upper jejunum were studied by scanning electron microscopy of osmium macerated/ ultrasonicated tissues. The present study showed that free cells adhering to the fenestrations increased in the upper jejunum two hours after feeding high-fat diet and the size of the fenestrations in this region also increased after feeding high-fat diet for 2 days. This enlargement of fenestrations may play an important role in increasing the efficiency of lipid absorption by facilitating the movement of chylomicrons from the intercellular space to the lamina propria.

Diet-related changes of basal lamina fenestrations in the villous epithelium of the rat small intestine: Statistical analysis on scanning electron microscopy

“…villi provide an important pathway for large nutrients, such as chylomicrons, to be released from the epithelial side to the space of the lamina propria (Azumi et al 2018). Moreover, we also previously demonstrated that the number of free cells passing through the fenestrations increased in the upper jejunum after feeding a high-fat diet, and the size of the fenestrations in this region also increased (Morita et al 2019). Because it is probable that the size and number of fenestrations are related to the efficiency of fat absorption, we strongly hypothesize that the increase in fenestration area may facilitate the passage of large substances such as chylomicrons.…”

“…We also suggested that basal lamina fenestrations are changed according to the dynamics of migrating leukocytes under certain dietary conditions. To further clarify the role of fenestrations in lipid absorption, we investigated the dynamics of basal lamina fenestrations under high-fat diet condition (Morita et al 2019). We showed that basal lamina fenestrations provide important pathways for the release of chylomicrons from the epithelial side to the side of the lamina propria and proposed that dynamic changes in basal lamina fenestration may play an important role in increasing or decreasing the efficiency of lipid absorption (Morita et al 2019).…”

“…To further clarify the role of fenestrations in lipid absorption, we investigated the dynamics of basal lamina fenestrations under high-fat diet condition (Morita et al 2019). We showed that basal lamina fenestrations provide important pathways for the release of chylomicrons from the epithelial side to the side of the lamina propria and proposed that dynamic changes in basal lamina fenestration may play an important role in increasing or decreasing the efficiency of lipid absorption (Morita et al 2019). These previous studies focused on short-term effects (i.e., 2 h after feeding) on the intestinal epithelium.…”

“…This inflammation is thought to be induced by the stimulation of cytokine release by intestinal immune cells and epithelial cells following fat absorption. Such inflammation might be explained by our previous findings that the number of free cells passing through fenestrations drastically increases in the upper jejunum 2 h after feeding a high-fat diet compared to those fed a normal diet (Morita et al 2019).…”