1. The current experiment was conducted to investigate the effect of
zinc sulphate (ZnSO4) and
zinc methionine (Zn-Met) on growth and their effect on plasma
growth hormone (GH) concentration,
growth hormone receptor (GHR) and
insulin-like growth factor I (
IGF-I)
mRNA expression in mice. 2. Ninety male KunMing (KM) mice were randomly divided into three treatments. The control group was fed on a basal diet containing 11.67 mg/kg of
zinc. The ZnSO4 group and Zn-Met group were fed on the diets supplemented with ZnSO4 or Zn-Met at 30 mg/kg (containing
zinc of 40.05 and 40.75 mg/kg, respectively). The mice were offered the test diets for 10 days.
Weight gains and food intake were measured at the end of the experiment,
zinc contents in liver and serum were determined using atomic absorption spectrophotometry; GH was determined by radioimmunoassay, the levels of GHR and
IGF-I mRNA were determined with reverse transcript polymerase chain reaction. 3. Both ZnSO4 and Zn-Met enhanced
weight gain and food intake in the mice, Zn-Met improved the growth and food intake more effectively than ZnSO4 did (P < 0.05). The both forms of
zinc had no effect on GH and the level of GHR
mRNA expression (P > 0.05) and they up-regulated the expression of
IGF-I mRNA (P < 0.05). As compared to ZnSO4, Zn-Met enhanced the level of
IGF-I mRNA significantly (P < 0.05). 4. Both ZnSO4 and Zn-Met had no effect on plasma GH and the expression of GHR
mRNA, but they enhanced the expression of
IGF-I mRNA.
Zinc methionine enhanced the
weight gain and up-regulated
IGF-I mRNA expression more effectively than ZnSO4.