AGE-DEPENDENT DIFFERENCES IN THE RATS CONDITIONED DEFENSIVE BURYING BEHAVIOR - EFFECT OF 5-HT1A COMPOUNDS

The ontogeny of conditioned defensive-burying behavior was studied in rats from 2 to 21 weeks of age. At early ages this parameter shows low values that gradually increase until the 11th week, decreasing steadi ly thereafter. Reactivity, measured by the burying-behavior latency, a ppeared increased in 2-week-old rats. The effect of the serotonergic(1 A) compounds: 8-OH-DPAT (0.25 and 0.5 mg/kg), ipsapirone, buspirone, a nd indorenate (at 2.5 and 5.0 mg/kg) was studied at 3, 7, 11, and 21 w eeks of age. All compounds produced a dose-dependent decrease in buryi ng behavior in rats of 7 and 11 weeks, while at the Week 21, only 8-OH -DPAT and indorenate reduced it. At 3 weeks of age, burying-behavior l atency was increased by all compounds, but burying behavior was not al tered. Motor coordination was affected by buspirone at all ages and by 8-OH-DPAT at the Week 21. Data are discussed on the bases of the deve lopment of defensive behaviors. (C) 1996 John Wiley & Sons, Inc.