Effect of in ovo ghrelin administration on subsequent serum insulin and glucose levels in newly-hatched chicks

Abstract

Ghrelin is a regulatory peptide in glucose homeostasis in animal species. Its effect in the avian embryo is unclear. The aim of this study was to investigate the effects of in ovo ghrelin administration on serum glucose and insulin levels of hatched chicks. A total of 250 fertilized eggs were divided into 5 groups; group T1 as control (without injection), group T2 (in ovo injected with 50 ng/egg ghrelin on day 5), group T3 (in ovo injected with 100 ng/egg ghrelin on day 5), group T4 (in ovo injected with 50 ng/egg ghrelin on day 10) and group T5 (in ovo injected with 100 ng/egg ghrelin on day 10). After hatching, serum insulin and glucose concentrations were determined. Group T4 and T5 showed significantly higher serum insulin levels (0.43 and 0.60 ng/ml, respectively) compared with T1, T2 and T3 (0.09, 0.10, and 0.23 ng/ml, respectively) in hatched chicks. Glucose concentrations have not been affected by in ovo administered ghrelin in all injected groups. It seems that embryonic β-cells were stimulated to secrete a considerable level of insulin in response to in ovo ghrelin in the late embryonic life. The observed stability of glucose rate suggests the incidence of insulin resistance at hatching time or in newly hatched chicks from in ovo ghrelin administered eggs on day 10.