Effects of dietary zinc deficiency on esophageal squamous cell proliferation and the mechanisms involved

Figure 1 Hematoxylin and eosin staining of the esophageal mucosa (200 ×). A: Zinc-sufficient group; B: Zinc-deficient (ZD) group; C: Zinc-replenished group. The esophageal mucosa of mice in the Zinc-sufficient group (A) consisted of a layer of basal cells that were arranged in an orderly manner. In the ZD mice (B), there was apparent basal cell hyperplasia in the esophageal mucosa, that resulted in two to four layers of basal cells arranged in a disordered manner, along with a visible squamous layer thickening. The esophageal mucosa of mice in the Zinc-replenished group (C) showed no obvious improvement compared to that of mice in the ZD group.

Figure 2 Immunohistochemical staining for cyclooxygenase-2, nuclear factor kappa B p65, nuclear factor kappa B p105, P38, and proliferating cell nuclear antigen in the esophageal mucosa (200 ×). A: Cyclooxygenase (COX)-2 was not expressed or was minimally expressed in the cytoplasm of normal cells; B: COX-2 expression was significantly increased in the esophageal mucosa of mice in the zinc-deficient (ZD) group; C: Two weeks of zinc-replenished (ZR) group reduced the COX-2 expression level; D: Nuclear factor kappa B (NF-κB) p65 showed a low expression level in the cytoplasm of normal cells; E: NF-κB p65 expression level significantly increased in the esophageal mucosa of mice in the ZD group; F: Compared with mice in the ZD group, in those in the ZR group, NF-κB p65 expression level did not change significantly in the esophageal mucosa; G: NF-κB p105 showed a low expression level in the cytoplasm of normal cells; H: NF-κB p105 expression level significantly increased in the esophageal mucosa of mice in the ZD group; I: Two weeks of ZR group reduced the NF-κB p105 expression level; J: P38 was expressed in small amounts in the cytoplasm and nucleus of normal cells; K: P38 expression was increased in the nucleus of esophageal mucosal cells in the ZD group; L: Compared with mice in the ZD group, in those in the ZR group, P38 expression level did not change significantly in the esophageal mucosa; M: Proliferating cell nuclear antigen (PCNA) showed a low expression level in the cytoplasm of normal cells; N: PCNA expression level significantly increased in the esophageal mucosa of mice in the ZD group; Compared with mice in the ZD group, in those in the ZR group, 2 wk of ZR reduced the PCNA expression level. ZS: Zinc-sufficient; ZD: Zinc-deficient; ZR: Zinc-replenished; COX-2: Cyclooxygenase-2; NF-κB: Nuclear factor kappa B; PCNA: Proliferating cell nuclear antigen.