Effect of Extrauterine Growth Restriction and Subsequent Catch-Up Growth on Cardiac Parameters: A Study on Wistar Rat Pups.

Objective: To study the long-term effect of postnatal growth restriction followed by catch-up growth on microscopic cardiac parameters in newborn Wistar rats. Methodology: This lab-based study was conducted at the Anatomy Department, CIMS Multan, on 120 neonate Wistar rats utilizing a rodent litter size manipulation model which mimicked human extrauterine growth restriction (EUGR) and catch-up growth. Initially, 30 pups were fed normally (Group N), while 90 were undernourished (Group R) to simulate EUGR. From days 11 to 21, the undernourished rats were separated into two subgroups: normal growth (RN, n = 30) and catch-up growth (RC, n = 60). The RC subgroup was further subdivided into accelerated (RCA) and slow (RCS) catch-up growth based on growth velocity. On day 60, microscopic cardiac parameters were assessed after euthanasia by ANOVA with a post-hoc Tukey test. Results: Malnourished rats with catch-up growth (RCS and RCA) had significantly increased left ventricle wall area, decreased left ventricle lumen area and a higher mean cardiomyocyte diameter than that of the normally fed (N) and malnourished than normally fed (RN) rats. Also, RCA pups had significantly thicker left ventricular walls and less lumen area than RCS pups. No difference in the collagen content of myocardium was detected among the subgroups. Conclusion: Accelerated and slow catch-up growth in rat pups decreases the left ventricular lumen area and increases the left ventricular wall + interventricular septum area significantly. Also, it increases the cardiomyocyte diameter in cardiac tissue.