MATERNAL ADMINISTRATION OF THYROTROPIN-RELEASING HORMONE (TRH) AND BETAMETHASONE (B) INCREASES LUNG COMPLIANCE IN PREMATURE LAMBS

Abstract

Administration of TRH and B to mothers decreases the incidence of bronchopulmonary dysplasia in premature babies. Fetal administration of TRH and Cortisol at 0.85 of gestation increases lung compliance in premature lambs. Since it is not known whether maternal administration of TRH plus B in sheep (in similar doses as in humans) modifies fetal lung compliance, we measured the changes of fetal lung volume induced “in vitro” by pressures of 40, 10, and 5 cm of H2O into the fetal trachea (V40, V10, V5). Twenty one fetal sheep at 0.83 of gestation were divided in three groups: Group TRH + B (n=5) the mothers received TRH (400 ug q 8 h for 6 doses, i.v.) plus B (12 mg q day for 2 doses, i.m.), mothers in Group B (n=5) received only B (same doses), while Group C were 11 control fetuses. The results are expressed as ml air/g of wet fetal lung (ml/g). Administration of TRH and B to mothers has greater effects on fetal lung compliance than B alone when given to the pregnant ewe at similar doses to those used in humans. Our results are consistent with the hypothesis that TRH and B act synergistically on fetal lung maturation.