[Changes in the heart of neonatal rats after cryptosporidial gastroenteritis of different degrees of severity].

Disturbances at the childhood age increase risk of the appearance of cardiovascular diseases decades later. The nature of this interconnection called ontogenetic programming is not completely understood. Valuable sources of knowledge about mechanisms of ontogenetic programming are data of interspecies study of biology of the body life cycles and of heart physiological capabilities. Taken into account the interspecies differences, these data allow finding the correct direction of experimental investigations. Results of studies of almost 100 homoiothermal species have shown the slow growth and a high loading on the heart at postnatal development to decrease its aerobic capability in adults. Basing on these data, we suggested that the neonatal gastroenteritis causing tachyarrhythmia, malabsorption, and the growth deceleration might lead to pathological changes in the heart. Our task was to evaluate the effect of cryptosporidial gastroenteritis of different degrees of severity on heart of the neonatal rats. By using methods of Real-Time PCR, immunocytochemistry, image analysis, and study of interatrial septum, we have established that a gradual increase of intensity of infestation with Cryptosporidium parvum oocytes causes sharp changes corresponding to the "all or nothing" response. At a weak infestation the interatrial septum was close (like in control), while significant changes in expression of isoforms of heavy chains of alpha- and beta-myosin were absent. At the intermediate and severe infestation, in the interatrial septum the foramen ovale was visualized and there were observed cardiac atrophy and a strong shift of ration of expression of myosin heavy chains toward the low-velocity beta chain. Thus, by disturbing the frequency-strength ratios and causing outflow of resources from the formed heart, the neonatal gastroenteritis produces pathological changes of the organ molecular and anatomical structures. Our results can be interest to evolutionary biologists and physicians, as they show importance of knowledge of evolutionary-comparative investigations for the search for novel risk factors of heart diseases and demonstrate interconnection between gastroenteritis, pathology of interatrial septum, and a change of composition of the main contractile proteins in cardiomyocytes.