Long-term consequences of neonatal blockade of bombesin (BN) receptors were examined in the present study. Rat pups were injected twice daily with [d-Phe6,ΨLeu13-Cpa14]BN(6-14), a BN receptor antagonist, at either high (10 mg/kg; HD group) or low (5 mg/kg; LD group) doses from postnatal day 1 through 8. Their behavioral responses to a variety of conditions were compared to those of rats neonatally injected with saline (SAL group) or animals handled but not injected during infancy (UNT group). Adult HD rats entered and spent more time on the open arms of the elevated plus maze than LD, SAL, or UNT animals. Under the conditions of a water deprivation schedule, neither central nor peripheral injections of BN differentiated the neonatally pretreated groups as determined by measures of grooming, feeding, and drinking behaviors. These results indicate that at the dosage regimen employed, neonatal injections of [d-Phe6,ΨLeu13-Cpa14]BN(6-14) had little effect on adult sensitivity to BN, but that such treatments could alter activity on the elevated plus maze through as yet unknown mechanisms.
- Bombesin antagonist