Transcription of the Amylin Gene in Newborn Dogs

Abstract

To understand the role of amylin, the novel pancreatic hormone, in fuel metabolism of neonatal mammals, the transcription of the amylin gene in newborn dogs was studied under different conditions, such as fasting, hyperinsulinemia, and hyper IGF-1. Our results showed (1) The amylin mRNA level decreased during a 24-h fasting period after birth, 59.1 ± 4.5% at 4 h, 80.1 ± 7.9% at 10 h, and 44.5 ± 3.0% at 24 h, compared to 0-h-fasted controls, respectively. In this period, the decreased mRNA level of the amylin gene and the increased mRNA levels of the gluconeogenic genes showed an inverse ratio relationship. (2) Euglycemic hyperinsulinemic clamp did not alter the amylin mRNA level, 39.6 ± 1.2% (hyperinsulinemia) vs 41.4 ± 3.1% (controls), in newborn dogs, but lowered the amylin mRNA by 35.3%, 64.7 ± 12.5% vs 100.0 ± 12.0%, in adult dogs. (3) Euglycemic hyper-IGF-1 clamp had no effect on the amylin mRNA levels of either newborn or adult dogs, 52.4 ± 9.1% (hyper IGF-1) vs 47.9 ± 4.3% (controls) in newborns and 95.2 ± 12.6% (hyper IGF-1) vs 100.0 ± 14.0% (controls) in adults. The data from the present study showed that amylin may be involved in carbohydrate homeostasis, but may not be able to stimulate gluconeogenesis in newborn dogs during a 24-h fasting period after birth. Whether amylin action may be another mechanism for neonatal hyperglycemia by inducing insulin resistance in peripheral tissues needs further investigation.