A Comparison of the Anorexic Effects of Chicken, Porcine, Human and Bovine Insulin on the Central Nervous System of Chicks

Abstract

The aim of the present study was to determine if some naturally-occurring substitutions of amino acid residues of insulin could act differentially within the central nervous system (CNS) of neonatal chicks to control ingestive behavior. Intracerebroventricular (ICV) administration of chicken insulin (20ng) inhibited food intake in ad libitum chicks over the 120-min experiment period. A lower dose (2ng) also shows a suppressive effect at 60min post-injection, but not at 30 and 120min. Similar to chicken insulin, a higher dose of porcine insulin (20ng) significantly inhibited food intake at 60 and 120min post-injection, but a significant difference is not detected at 30min post-injection. Treatment with human and bovine insulin had no effect in this study. Finally, we compared the effect of ICV injection of chicken and porcine insulin on food consumption in starved chicks. The results of the present study indicate that chicken insulin has a higher potent ability to depress feeding behavior in the CNS compared with porcine, human, and bovine insulin. Therefore, it seems that the ranking in order of potency of the insulins on the anorexic effect in neonatal chicks is chicken insulin>porcine insulin>human insulin>bovine insulin. It is suggested that the 8th-10th amino acids of the A-chain and/or the C-terminal amino acid of the B-chain in insulin have an important role in bioactivity in the CNS with special reference to feeding behavior.