Characterization and estrogen regulation of uterine growth factor activity

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Title: Characterization and estrogen regulation of uterine growth factor activity
Author: Beck, Candace
Abstract: Estradiol -17B has been shown to stimulate glucose transport , measured by phosphorylation of 2 -deoxyglucose , and stimulate DNA synthesis , as measured by 3H -thymidine incorporation , In rat uterus in vivo . Attempts to demonstrate these responses in uterine cells in primary culture and in uterine tumor cells In culture have been unsuccessful . These observations led to the hypothesis that some responses to estradiol are mediated through the local action of peptide factors . Acid extracts of rat , bovine and rabbit uterus stimulated glucose transport and DNA synthesis in uterine tumor cells and in primary cultures of rat uterine cells . The stimulation of glucose transport was of the same magnitude (1 .5 -to 3 .0 -fold ) and followed the same time course (maximum stimulation at 2 -3 h ) as estradiol stimulation in vivo . Uteri from estradiol treated rats contained 4 times more glucose transport -stimulating activity as did control rat uteri . The activity was acid and heat stable , was inactivated by trypsin , but not removed by dextran -coated charcoal treatment . The activity eluted in 6 -12 kDa range on Sephadex G -50 . DNA synthetic activity in rat uterine homogenates was elevated 3 -fold within 18 -24 h after estradiol injection and remained elevated with subsequent Injections . The growth -promoting activity was acid and heat stable , was reduced by trypsin but not reduced by treatment with dextran -coated charcoal . Gel filtration showed molecular weight heterogeneity with activity eluting at MW 10 ,000 -30 ,000 . The effect of purified growth factors on DNA synthesis in primary cultures of rat uterine cells was examined . Epidermal growth factor (EGF ) , basic fibroblast growth factor (bFGF ) , and transforming growth factor -B (TGFB ) had no effect on 3H -thymidine incorporation under optimal conditions of incorporation . Relaxin and multiplication stimulating activity (MSA ) demonstrated a stimulatory effect only at high concentrations , 207 % of control at 100 |ag /ml and 175 % of control at 100 ng /ml , respectively . Insulin stimulated incorporation 350 % at 100 ng /ml , insulinlike growth factor -l (IGF -I ) stimulated incorporation 300 -400 % at 10 -100 g /ml , and platelet -derived growth factor (PDGF )stimulated incorporation 450 % at 3 units /ml . When the positive effectors (insulin , IGF -I , MSA , and PDGF ) were analyzed either combined or individually in the presence of uterine extract , the level of stimulation was greater than the maximum stimulation bserved with extract alone and approached that seen with 10 % serum . Uterine extracts from estradiol treated and control rats were analyzed for IGF -I by radioimmunoassay . IGF -I was elevated 500 -1000 % in estradiol treated extracts relative to control levels . In summary , estradiol increases the growthpromoting activity and glucose transport -stimulating activity of uterine extracts . IGF -I was a positive stimulator of DNA synthesis in primary uterine cultures and was elevated in uterine extracts . This growth factor may be involved in the stimulation of DNA synthesis In rat uterus by estradiol .
URI: http : / /hdl .handle .net /2346 /10978
Date: 1988-08

Citation

Beck, Candace Characterization and estrogen regulation of uterine growth factor activity. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /10978 .

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