Chloroquine-induced retardation of foetal lung maturation in rats

Chloroquine (CQ) is a widely used drug and its administration has been reported to increase surfactant- associated phospholipids in lungs. We have used histomorphometric techniques to study the effects of CQ on foetal lung maturation in rats. CQ (40mg/kg BW) or saline was administered to pregnant rats on days 20 and 21 of gestation. A third group received the same dose of CQ on days 20 and 21, and in addition, hydrocortisone (HD; 25 mg/kg BW) on day 21 of pregnancy. Foetuses were delivered by hysterotomy on day 22. The lungs were weighed, fixed in Bouin's fixative and embedded in paraffin. Morphometric studies were performed on 5 microns-thick sections. The lung weight/100g BW, the volume density of lung saccular spaces, and the cross-sectional area and volume of the saccular spaces were reduced but the numerical density of the saccules was not decreased in foetuses exposed to CQ. With the exception of lung weights, which were lower in the foetuses exposed to CQ and HD, there were no other differences between this group and that exposed to CQ only. The results suggest that CQ attenuates the expansion of saccular spaces which occurs in preparation for post-natal gaseous exchange, and thus CQ retards foetal lung maturation. Although HD further reduced lung weights as expected from its reported action on foetal lungs, it did not reverse the CQ-induced retardation in lung maturation.