Surfactant protein A expression is delayed in fetuses of streptozotocin- treated rats

The content and distribution of the 26-to 38-kDa surfactant protein (SP-A) and its mRNA were determined in fetuses of control and streptozotocin (STZ)- treated Sprague-Dawley rats using immunohistochemistry, RNA blotting, and in situ hybridization. Female rats were treated with 50 mg/kg STZ before mating, and the fetuses were killed at fetal days 18-21 or on neonatal days 1 and 2 (day of birth = end of day 22). SP-A was barely detectable on fetal day 18 in controls and easily detected by fetal day 21. In the STZ group, SP-A was decreased compared with controls at fetal days 18-21. However, by neonatal days 1-2, there were no significant differences in SP-A levels between groups. SP-A mRNA was detectable at fetal day 18 in controls, but it was decreased in the STZ group at day 18-21 (P < 0.02) and differences were no longer detected by neonatal days 1-2. SP-A and SP-A mRNA accumulated with advancing gestational age in both groups until neonatal days 1-2. The differences in SP-A and SP-A mRNA levels in the two groups diminished with advancing age but remained significant at fetal day 21. These data suggest that STZ-induced diabetes interferes with normal expression of SP-A in the developing fetal lung.