Use of selective serotonin reuptake inhibitors (SSRIs) is common during pregnancy. Fetal exposure to SSRIs is associated with persistent pulmonary hypertension of the newborn (PPHN); however, a direct link between the two has yet to be established. Conversely, it is well known that PPHN can be caused by premature constriction of the ductus arteriosus (DA), a fetal vessel connecting the pulmonary and systemic circulations. We hypothesized that SSRIs could induce in utero DA constriction. Using isolated vessels and whole-animal models, we sought to determine the effects of two commonly prescribed SSRIs, fluoxetine and sertraline, on the fetal mouse DA. Cannulated vessel myography studies demonstrated that SSRIs caused concentration-dependent DA constriction and made vessels less sensitive to prostaglandin-induced dilation. Moreover, in vivo studies showed that SSRI-exposed mice had inappropriate DA constriction in utero. Taken together, these findings establish that SSRIs promote fetal DA constriction and provide a potential mechanism by which SSRIs could contribute to PPHN. mouse; ductus arteriosus; SSRI; fluoxetine; sertraline; serotonin; PPHN
NEW & NOTEWORTHY
This study is the first to elucidate a mechanism by which serotonin reuptake inhibitors (SSRIs) alter ductus arteriosus tone. It also puts forth the notion that SSRIs may contribute to persistent pulmonary hypertension of the newborn by causing premature fetal ductus constriction.THE DUCTUS ARTERIOSUS (DA) is an essential fetal vessel connecting the pulmonary and systemic circulations. During fetal life, the DA, responding to low oxygen tension, nitric oxide, and prostaglandin signaling, remains patent to shunt blood to the aorta, bypassing the immature, uninflated lungs. At birth, increasing blood oxygen content and decreasing prostaglandin levels stimulate DA closure, allowing appropriate perfusion of the newly inflated lungs (7,8,43,52). The timing of DA closure is tightly regulated. If the DA fails to close (patent DA), serious consequences including pulmonary hemorrhage, parenchymal lung disease, intraventricular hemorrhage, and death can ensue. Conversely, premature DA constriction in utero is also undesirable and can lead to life-threatening conditions, including right ventricular hypertrophy, functional pulmonary atresia, absent pulmonary valve syndrome, hydrops fetalis, and persistent pulmonary hypertension of the newborn (PPHN) (18,20,23,31,32).PPHN is a disorder characterized by sustained elevated pulmonary vascular resistance (PVR). During fetal life, PVR is high due to a number of factors, including mechanical compression of the pulmonary arterioles by fluid-filled alveoli, low fetal oxygen tension, low levels of vasodilators (prostacyclin, nitric oxide), and elevated levels of vasoconstrictors (endothelin-1, thromboxane) (37). At birth, PVR should fall to facilitate a smooth transition from fetal to extrauterine life. However, in some cases, the pulmonary vasculature fails to relax, causing PPHN, a disorder accompanied by hypoxemia and right-...