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 b etamethasone 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 consis ted of a single or a double SC dosing of either betamethasone (Celesto ne soluspan 0.2 mg on GD 14; 0.1 mg on GD 13 to 16; 0.1 mg bid on GD 1 4 and 15; 0.1 mg bid on GD 13 to 16) or saline (0.25 mi on GD 13 to 16 ; 0.25 mi bid on GD 13 to 16). The percent of pups exhibiting separati on vocalization was temporarily less at PND 5 after betamethasone expo sure to four doses (p < 0.05) and to eight doses (p < 0.01). The perce nts of pups being successful in homing (PND 9) and in responding to st artle stimulation (PND 12-15) were not different between the betametha sone-exposed and placebo-exposed groups. Exploratory performance in th e radial arm maze revealed no delay in the activities of juvenile and adult offspring exposed to betamethasone. The percent of male offsprin g 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 juvenil e and adult offspring, after a single dose of betamethasone was not re plicated in this multidose study. These data indicate that prenatal ex posure to betamethasone did not affect the mouse offspring's long-term responses to motivation/anxiety testing. (C) 1998 Elsevier Science In c.