MORPHOMETRIC CHARACTERISTICS OF RAT’S HEART CORONARY ARTERIES IN THE POSTNATAL PERIOD IN NORMAL CONDITIONS AND AFTER PRENATAL ADMINISTRATION OF GLUCOCORTICOIDS

Abstract

Any disturbance of the formation or organization of connective tissue such as undifferentiated connective tissue disease (UCTD) can cause various pathological conditions of the heart. The synthesized glucocorticosteroid dexamethasone is routinely administered to pregnant women in the third trimester with high risk of preterm delivery or to improve the surfactant system maturation in the fetus. The safety of using synthetic glucocorticoids in pregnant women is the subject of active discussions due to possibilities of dexamethasone to accelerate maturation of cardiomyocytes and leading to disorganisation of the connective tissue fibers. Yet, changes in rat`s heart coronary arteries caused by intrauterine administration of dexamethasone are still not studied. Objective. The purpose of this research is to make morphometric characteristic of rat’s heart coronary arteries in the postnatal period in normal conditions and after intrauterine administration of glucocorticoids. Object and methods. 144 hearts of laboratory rats were investigated. All animals were divided into three groups: the first one included intact animals; the second was comprised of experimental animals, who were injected by dexamethasone by intrauterine approach after a median laparotomy of pregnant rat at the 17th day of pregnancy; the third group was formed by control animals, who were injected by saline solution in equal volume, by the same way, at the same day. Rats’ hearts were analyzed from birth up to the 45th day of life. Serial sections were stained with orcein. Morphological study of thickness of coronary arteries intima-media complex were performed. Method of variation statistics have been used during the research. Results and discussion. It was found that thickness of intima-media complex of rat’s heart coronary arteries increases gradually from birth to 45 day of postnatal life in and increases 2,95-fold and 2,87-fold in intact and control group respectively. The greatest increasing of thickness of artery wall occurs between 14 and 21 days after birth. After prenatal administration of glucocorticoids, it was observed significant decreasing of thickness of complex intima-media of coronary arteries on 1, 3, 5, 14, 21, 30 and 45 days of postnatal life. The most intensive increasing of thickness of artery wall observed between 5 and 9 days after birth in experimental group. All described changes may be evidences of disturbance of formation of connective tissue fibers and early maturation of coronary arteries. Conclusions. The prenatal administration of dexamethasone leads to significant thickening of the rat’s heart coronary arteries walls on 1, 3, 5, 14, 21, 30 and 45 days of postnatal life in comparison with control group. All described changes may be a manifestation of UCTD and vascular dysfunction and form background for developing of different pathologic conditions of the heart and coronary arteries in adult life

Keywords

• morphology
• coronary arteries
• heart
• intrauterine administration
• glucocorticoid.