Titolo della tesi: Phosphodiesterases expression during murine cardiac development and Role of phosphodiesterase 5 in neonatal cardiomyopathy induced by gestational diabetes
Phosphodiesterases (PDEs) are enzymes that hydrolyze cyclic nucleotides, such as cGMP and cAMP. PDEs plays fundamental roles controlling the intracellular levels of cAMP and cGMP in physiological conditions, while alterations in expression and functionality of these enzymes are associated with cardiac diseases. Little is still known about the role of phosphodiesterases during the cardiac development. In the first part of the present study, the expression of PDEs at different stages of cardiac development was investigated. Wild-type mice (C57BL/6) were mated and embryos were collected from 14.5 to 18.5 days of development. Data obtained by qRT-PCR and western blots show that seven different PDE isoforms are expressed during heart development but, among these, only PDE1C, PDE2 and PDE5 are modulated from E14.5 to E18.5 suggesting their involvement in specific processes of heart formation. In the second part, the potential role of PDE5 in neonatal cardiomyopathy induced by gestational diabetes (GD) was investigated. To accomplish this goal, PDE5+/- mice were mated and diabetes was induced by streptozotocin injection in pregnant mouse. Morphological analysis by hematoxylin-eosin stain showed that almost 60% of PDE5+/+ newborns exposed to gestational diabetes presented cardiomyopathy, 40% of PDE5+/- newborns exposed to gestational diabetes presented cardiomyopathy and only 37,5% of knockout PDE5 presented heart malformation. Data from in vitro experiments with isolated neonatal cardiomyocytes exposed to high levels of glucose and treated by sildenafil shown that pharmacological inhibition of PDE5 was able to restore the altered protein expression of Tbx2 but no tbx20 in response to hyperglycemia. Together, our results suggest that reduction in the PDE5 levels protects neonatal heart from cardiomyopathy due to GD.