Bombesin-induced behavior in infant rats.

The behavioral effects of bombesin in 5-, 10- and 20-day-old rat pups have been investigated and the peptide was found to induce scratching (1, 10 mg/kg IP) and grooming (10 mg/kg IP) as early as 5 days after birth. Bombesin did not produce any other overt activities in the developing pups in doses of up to 10 mg/kg, however, lower doses of the peptide (0.1, 1 mg/kg IP) reduced intake of a wet mash diet in deprived 15-day-old rat pups resulting in significant decreases in body weight compared with control animals. These behavioral responses agree with the well-documented effects of bombesin in adult rats and are also in accordance with results from biochemical studies which have shown the existence of receptors for bombesin-like peptides in the rat central nervous system from an early age.