Expression of growth hormone and insulin-like growth factor-1 in the temporal cortex of a Lewis dwarf model rat / 中国组织工程研究

ABSTRACT

BACKGROUND:Insulin-like growth factor-1(IGF-1), a main active factor in growth hormone (GH), plays various biological functions, such as improving cognitive ability and anti-apoptotic action. OBJECTIVE:To detect the expressions of GH and IGF-1 in the temporal cortex of Lewis dwarf rats, and to explore the effect of different concentrations of GH on the differentiation of hippocampal nerve stem cels (NSCs). METHODS:Lewis dwarf rats aged 11(adult) and 20 (senile) month olds and normal wild-type rats were euthanized by decapitation, underwent the craniotomy quickly, and the temporal cortex in the cold saline was extracted. GH and IGF-1 levels were detected using western blotting. After isolation, purification and identification of the rat hippocampal NSCs, the effect of GH in different concentrations (10, 30, 90μg/L) on the NSCs differentiation was determined at 96 hours after culture. RESULTS AND CONCLUSION:The GH level in the temporal cortex did not differ significantly among rats (P > 0.05). While the IGF-I level in the temporal cortex of Lewis dwarf rats was significantly higher than that of the wild-type rats (P < 0.05). The GH level in the temporal cortex of adult female Lewis dwarf rats was significantly lower than that of the male rats (P < 0.05). Immunofluorescence showed that the proportion ofβ III-tubulin-positive neurons was significantly higher than that in the control group (P < 0.05) after the hippocampal NSCs and precursor cels cultured for 96 hours with GH (30μg/L), but there was no significant difference between the control group and treatment group with GH of 10 or 90μg/L. These results suggest that GH and IGF-I are expressed in the temporal cortex of both Lewis dwarf and wild-type rats which are independent from pituitary GH and the peripheral circulating IGF-1. Additionaly, GH can promote the differentiation of hippocampal NSCs and precursor cels into neurons.