Enhanced Inflammatory Response to Acute Ozone Exposure in Rats during Pregnancy and Lactation

Experimental evidence from several studies suggests that pregnantanimals and women are more susceptible to oxidants than nonpregnantcontrols. In the study reported here, we sought to determinewhether pregnant rats are more sensitive than age-matched virginfemales to the inflammatory effects of ozone, a gaseous oxidantof considerable environmental significance. Rats at severalstages of pregnancy and lactation, as well as age-matched virginfemales, were exposed to 1 ppm ozone for 6 hr. Controls weresham-exposed to pure air for an identical period of time. Bronchoalveolarlavage was performed 24 hr after the beginning of exposure,and components of the lavage fluid considered to be indicatorsof inflammation were used to assess the severity of pulmonaryinflammation. The results of this experiment showed that significantlyenhanced sensitivity to ozone-induced pulmonary inflammationdevelops during pregnancy, is maintained during lactation, anddisappears following lactation. Implicit in this pattern ofdifferential sensitivity in rats is the possibility of a similarpattern of inflammatory response in analogous groups of humansas well as the potential for applicability to other oxidativepollutants.