Effect of in utero exposure to betamethasone on motivation/anxiety testing in mice offspring.

In utero exposure to a single dose of the long-acting corticosteroid betamethasone at GD 14 has been shown to induce specific differences in motivation/anxiety testing among offspring. Because multidosings are desired to enhance fetal lung maturation, our objective was to compare effects of multidosings of betamethasone with a placebo on postnatal tests of motivation and anxiety. Sixty gravid CD-1 mice were randomly assigned to receive one of six treatment regimens (n = 10) that consisted of a single or a double SC dosing of either betamethasone (Celestone soluspan 0.2 mg on GD 14; 0.1 mg on GD 13 to 16; 0.1 mg b.i.d. on GD 14 and 15; 0.1 mg b.i.d. on GD 13 to 16) or saline (0.25 ml on GD 13 to 16; 0.25 ml b.i.d. on GD 13 to 16). The percent of pups exhibiting separation vocalization was temporarily less at PND 5 after betamethasone exposure to four doses (p < 0.05) and to eight doses (p < 0.01). The percents of pups being successful in homing (PND 9) and in responding to startle stimulation (PND 12-15) were not different between the betamethasone-exposed and placebo-exposed groups. Exploratory performance in the radial arm maze revealed no delay in the activities of juvenile and adult offspring exposed to betamethasone. The percent of male offspring that fought as juveniles and as adults was not different between the betamethasone-exposed and the placebo-exposed groups. The previously reported altered responses using the elevated plus maze, among juvenile and adult offspring, after a single dose of betamethasone was not replicated in this multidose study. These data indicate that prenatal exposure to betamethasone did not affect the mouse offspring's long-term responses to motivation/anxiety testing.