Effects of stanniocalcin hormones on rat hepatic glucose homeostasis under fed and fasted conditions

Abstract

To test the hypothesis of conservation of stanniocalcin 1 and 2 (STC-1; STC-2) metabolic functions in vertebrates, we performed an in vitro study to determine if these hormones are implicated in regulation of the gluconeogenesis pathway, glycogen synthesis, and ¹⁴C-glucose conversion to ¹⁴CO₂ in livers from fed and fasting rats (Rattus norvegicus). Stc1 and Stc2 gene expressions increased in the liver after fasting. STC-1 participated in the regulation of the hepatic gluconeogenesis pathway in rats when the precursor was ¹⁴C-lactate. STC-2 demonstrated variational signaling on rat hepatic gluconeogenesis activity and Pck1 gene expression, decreasing levels in the fed state when the substrate was ¹⁴C-alanine and increasing levels during fasting when the substrate was ¹⁴C-lactate. At the concentrations used in this study, STC-1 and STC-2 did not affect glycogen concentration and synthesis from ¹⁴C-glucose or ¹⁴C-glucose conversion to ¹⁴CO₂ in the livers from fed or fasting rats. These findings highlight the role of stanniocalcins in the hepatic gluconeogenesis pathway in mammals and confirm the conservation of STC-1 and STC-2 metabolic functions in the vertebrates.

Keywords: Glucose Homeostasis; Rat Liver; Stanniocalcin.