Regulation of insulin-like growth factor-I and thioredoxin expression by estradiol in the reproductive tract of the prepubertal female lamb

Estradiol (E-2) has been shown to be an important uterine growth promoting molecule in the ovariectomized (ovx) rat. which increases the mRNA levels o f insulin-like growth factor-1 (IGF-I) and the redox enzyme thioredoxin. Th e aim of this study was to explore the role of E-2 in the regulation of IGF -I and thioredoxin in the reproductive tract of the prepubertal female lamb . Twenty 3-month-old lambs were treated with i.m. injections of E-2 at 24 h intervals. The animals were sacrificed 12 or 24 h after the last injection , and 72 h was the longest treatment period. The mRNA levels of thioredoxin and IGF-I were determined by a solution hybridization technique. There was a 5-fold increase in the cervical IGF-I mRNA level 12 h after the first E, injection. The uterine IGF-I mRNA level was doubled after 12 h and this in crease was maintained during the rest of the experimental period. The IGF-I mRNA level in the oviducts was more than doubled 12 and 24 h after the E-2 injection, then the level decreased towards the initial level. The thiored oxin mRNA level in the cervix was increased 4-fold after 24 h. whereas no s ignificant effect was seen in the uterus. The thioredoxin mRNA level in the oviduct was more than doubled 12 and 24 h after the first E-2 injection. T hus. estradiol regulates the expression of IGF-I and thioredoxin in the rep roductive tract of prepubertal lambs. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.