Effect Of IGF-Ⅰ And EGF On Priliferation And Differentiation Of Rat Preadipocytes

To investigate the roles of insulin-like growth factor (IGF-I) and epidermal growth factor (EGF) in the course of proliferation and differentiation of preadipocyte, the SV cells of normal and healthy 20 days old male SD rats were exposed to IGF-I and EGF.The preadipocytes were gained from normal and healthy 20 days old male SD rats, and were cultured in vitro under the condition: 10%FBS M199 as the culture medium,5%CO2,37℃ ,and without insulin.Cell counting was employed to find out the population doubling-time and growth curve to explore the influence of IGF-I and EGF on the proliferation of the rat preadipocytes. The method of MTT was used too. The differentiated cell was stained with oil-red O, HE and Giemsa to display morphological differentiation. The quantity of oil-red O extracted from oil-red O stained cells with isopropyl alcohol was measured by optical density detection. This optical density, together with proportion of lipid contain cells, were used to describe the differentiation of the preadipocytes.In this experiment, 80 ng/mL IGF-I and 50 ng/mL EGF were the most appropriate concentrate to promote the proliferation of rat preadipocytes, with the population doubling-time of 44.24 hours and 48 hours , respectively. IGF-I and EGF show synergistic effect of each other in the action of promotion the proliferation of rat preadipocytes. And this synergistic effect was influenced by the concentration of the two growth factors and which stage the preadipocytes was on.IGF-I can also promote differentiation of the rat preadipocytes, while proliferation and differentiation were almost incompatible course, with higher oil-red O optical density,and higher proportion of lipid contain cells. EGF could lower oil-red O optical density and proportion of lipid contain cells while it was added from 1 d to 10 d of the culture But EGF could only fulfil it inhibitory function when it were added to the medium before the differentiation was activated. It cannot block the procedure of activated differentiation. From 3d to 7d of culture is the most important stage during which both the two growth factors exert its influence on differentiation of the rat preadipocytes.80 ng/mL IGF-I could, while 50 ng/mL EGF could not, promote the protein contain of the cultured rats preadipocyte. In experiment, the primary cultured rats preadipocyte becomes lighter as the differentiation was proceeding. Some differentiated rat adipocyte cannot be collected by centrifuge.