Meeting Abstract
Glucocorticoids are a class of steroids that are normally administered to women whose infants are at risk of being born prematurely. This treatment has been shown to combat the risk of Respiratory Distress Syndrome, but in some cases has led to developmental consequences later in life. Therefore, it is important to understand the different physiological effects of exposure to prenatal steroids. Past studies in our laboratory have been conducted on the scalenus, an accessory breathing muscle, from guinea pig fetuses that were exposed to multiple courses of betamethasone. In these studies, the proportions and diameters of type IIX and IIA fast-twitch fibers, the citrate synthase (CS) activity, and the expression of myoglobin were determined in steroid-treated and untreated prenatal muscles. However, to know if the features of the prenatal steroid-treated fetal muscles reflect acceleration of their development, the scalenus of neonatal guinea pigs must be characterized. Thus, we examined the morphology of the neonatal guinea pig scalenus and compared it to the results from the studies of the fetal muscle. The proportions of IIX and IIA fast-twitch fibers were quantified through antibody staining and the diameters of these fibers were measured using ImageJ. CS activity was determined with enzyme kinetic assays and SDS-PAGE was used to measure the myoglobin concentration in the one-day-old neonatal muscles. The features of the neonatal scalenus will be compared to those of fetal muscles exposed to prenatal steroids using ANOVAs. If the neonatal muscle is found to not significantly differ in morphology from those of fetuses exposed to prenatal steroid, then this would indicate that the steroid-treated prenatal muscles experienced accelerated development.
