The influence of D2 Dopamine receptor on feeding, drinking and weight gain of nestling in pigeons

It is well known that D2 Dopamine receptors affect the feeding and drinking behaviours in mamallian, but there are a little data related to birds. The present work examines the possible role of Dopamin D2 receptor in the control of feeding, drinking and weight gain of young chicken in pigeons. This study was designed at 3 experiments; experiment 1: 8 adult male and 8 adult female pigeons (350-420g) were used respectively in a design of replicated 4×4 latin sequer in which, days and birds were the bloded factor. The animals were kept individual open air cages with ambient temperature (70° - 80°f) and a 12h light / dark cycle. In each experiment, 0,10,20 and 40 mg/100g sulpiride, as a potent D2 Antagonist were injected subcotaneously. All solutions were injected at 2 – day intervally, so that each bird received the solution during 7- day test period. Food and water intake were measured at 1,2,3 and 24h after injection, and the following results were obtained: sulpiride increased food intake in the females but not in males and increased water intake in the males but not in females 24h after injection. Experiment2: 40 female pigeons divided in 5 groups, group1 (solvent), group2-4, received Bromocriptin (Br) (0.5, 1, 2 mg/kg), group5 (No injection), the results showed that Br (2mg/kg) decreased food intake. Experiment3: 12 pair of parents received sulpiride during nestlings were 1 to 7 days of age and weight gain of nestling was calculated. The above findings showed that D2 receptors in pigeon as well as rat have a determinat role in feeding regulation, this receptors seems to increased weight gain of nestlings through crop sac secretion.