Heat shock protein 70 is upregulated in the intestine of intrauterine growth retardation piglets

Abstract

The objective of this study is to investigate the expression and distribution of heat shock protein 70 (Hsp70) in the intestine of intrauterine growth retardation (IUGR) piglets. Samples from the duodenum, prejejunum, distal jejunum, ileum, and colon of IUGR and normal-body-weight (NBW) piglets were collected at birth. The results indicated that the body and intestine weight of IUGR piglets were significantly lower than NBW piglets. The villus height and villus/crypt ratio in jejunum and ileum of IUGR piglets were significantly reduced compared to NBW piglets. These results indicated that IUGR causes abnormal gastrointestinal morphologies and gastrointestinal dysfunction. The mRNA of hsp70 was increased in prejejunum (P < 0.05), distal jejunum (P < 0.05), and colon in IUGR piglets. However, the hsp70 mRNA in ileum of piglets with IUGR was decreased. Similar to hsp70 mRNA, the protein levels of Hsp70 in prejejunum (P < 0.05), distal jejunum, and colon (P < 0.05) in IUGR piglets were higher than those in NBW piglets. These results indicated that the expression of Hsp70 in the intestinal piglets was upregulated by IUGR, and different intestinal sites had different responses to stress. Meanwhile, the localization of Hsp70 in the epithelial cells of the whole villi and intestinal gland rather than in the lamina propria and myenteron suggested that Hsp70 has a cytoprotective role in epithelial cell function and structure.

Fig. 1

The levels of Hsp70/β-actin in the intestines of piglets. Mean differences between values for IUGR piglets and NBW piglets are indicated by *P < 0.05 or **P < 0.01. Values indicated are mean ± SD

Fig. 2

The levels of Hsp70 in the intestines of piglets (ng/ml). Mean differences between values for IUGR piglets and NBW piglets are indicated by *P < 0.05 or **P < 0.01. Values indicated are mean ± SD

Fig. 3

The levels of hsp70 mRNA in the intestinal piglets. Mean differences between values for IUGR piglets and NBW piglets are indicated by *P < 0.05 or **P < 0.01. Values indicated are mean ± SD

Fig. 4

Localization of Hsp70 in the intestine of IUGR piglets. Scale bar = 10 μm a Hsp70 (arrow) was detected predominantly in the cytoplasm of the epithelial cells of the whole villi rather than in the lamina propria and myenteron in duodenum of IUGR piglets (IHC staining) b Positive immunolabeling of Hsp70 (arrow) was localized mainly in the cytoplasm of the epithelial cells of the whole villi in jejunum of IUGR piglets (IHC staining) c Diffuse Hsp70-positive signals (arrow) were observed, particularly in epithelial cells and gland of colon in IUGR piglets (IHC staining) d Lack of Hsp70 immunoreactivity when antibody was omitted (IHC staining)