Treatment of Rats with Dexamethasone or Thyroxine Reverses Zinc Deficiency-Induced Intestinal Damage ,

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Abstract
Structural and functional damage to the intestine and the potential beneficial effects of dexamethasone (Dex) and thyroxine (T4) were examined in zinc-deficient rats. Rats were assigned to zinc deficient (ZD), control (C) or pair-fed (PF ) groups and fed for 40 d a zinc deficient (1 mg/kg) diet (ZD rats) or a similar diet supplemented with 50 mg Zn/kg (C and PF rats). Some rats of the ZD group were treated for the last 10 d with low (250 mg/kg) or high (5 mg/kg) doses of Dex or with T4 (100 mg/kg). Serum corticosterone of T4-treated ZD rats did not differ from untreated ZD rats. Serum T4 of T4-treated ZD rats did not differ from C rats. ZD rats developed ulcerations, inflammation and edema in the small intestine, particularly in the jejunum. PF rats did not show mucosal changes relative to C rats. ZD rats showed significantly lower crypt cell production rate (CCPR) and labeling index (LI) in the three intestinal regions, and lower cell migration rate and higher turnover time in the duodenum relative to C rats. Sucrase and maltase activities of ZD rats were significantly lower than C rats in the three mucosal regions. Treatment with the low dose of Dex resulted in fewer ulcerations compared with ZD rats. In rats administered the high dose of Dex or T4, all morphological alterations disappeared; the CCPR, LI, cell migration rate, cell turnover time and disaccharidase activities did not differ from C rats. In conclusion, Dex and T4 exert beneficial effects on zinc deficiency-induced intestinal alterations in rats.