Effects of prenatal exposure to chlorodiazepoxide on ultrasonic calling and early postnatal development in A.P. mice.

1. The effects were studied of injecting pregnant Alderley Park mice with the benzodiazepine agonist chlordiazepoxide (CDP) at doses of 10 and 30 mg/kg during the last 9-10 days of gestation on the early behaviour and development of their offspring. 2. All neonates were fostered to non-treated lactating dams to eliminate maternally-mediated effects. 3. Early development and responses to anxiety-related situations were studied by recording body growth, righting reflex, rooting behaviour, cliff avoidance reflex and ultrasonic "distress" calling. 4. Drug treatment: (a) retarded postnatal body growth; (b) delayed the righting and cliff avoidance reflexes; (c) augmented rooting behaviour and (d) produced an overall increase in ultrasonic calling (but with the higher dose decreasing emission on days 1-2). 5. Exposure to CDP during foetal life retards motor development and physical maturation; produces a sedative/anxiolytic action (especially at high doses) and may modify the sensitivity of GABA-BZP receptor complex to endogenous receptor ligands.