Expression of mRNAs for the Estrogen and Progesterone Receptors, Insulin-like Growth Factor-I and Thioredoxin in the Porcine Cervix.

Abstract

Abstract. Studies of the cervix are important for the understanding of structural and physiological changes occurring during the estrous cycle and the second half of pregnancy. The aim of the present study was to illustrate the structural differences seen in the porcine cervix, in relation to the estrogen/progesterone status of the animal. Tissue samples from the uterine portion of the cervix were collected from 23 gilts and assayed with solution hybridization for their contents of mRNA for the estrogen receptor (ER), progesterone receptor (PR), insulin-like growth factor-I (IGF-I) and thioredoxin, all known to vary with reproductive status. The mRNA levels of ER and PR were highest prior to standing estrus. The PR mRNA level was higher at term compared to mid pregnancy, whereas the serum progesterone concentration was the opposite. The thioredoxin mRNA level was highest around standing estrus and at term pregnancy. The IGF-I mRNA level had a peak just after standing estrus, while no significant changes were seen during pregnancy. Thus, steroid hormone involvement in the changes of the porcine cervix during estrus and term pregnancy are likely to be mediated via variations in the expression of gonadal steroid hormone receptors and substances with growth factor or cytokine-like activities. Key words: Pig, Cervix, mRNA, Steroid receptors, IGF-I, Thioredoxin (J. Reprod. Dev. 45: [143][144][145][146][147][148][149][150] 1999) marily of smooth muscle surrounded by an extracellular matrix of loosely organized collagen fiber bundles with proteoglycans dispersed among them [2]. The vaginal cervix of the pig allows anchoring of the corkscrewed glans of the boar penis, thus eliciting the ejaculation reflex and resulting in deposition of the ejaculate in the smaller and less extensible uterine part of the cervix. In contrast to nvestigating the regulation of cervical remodeling is important in order to understand the I physiological changes during the estrous cycle and pregnancy. The porcine cervix can be divided into a uterine and a vaginal part [1] and it consists pri-