Hypothalamic glucagon signaling in fasting hypoglycemia

Vigneshwaran Pitchaimani, Somasundaram Arumugam, Rajarajan Amirthalingam Thandavarayan, Vengadeshprabhu Karuppagounder, Mst Rejina Afrin, Remya Sreedhar, Meilei Harima, Hiroshi Suzuki, Shizuka Miyashita, Kenji Suzuki, Masahiko Nakamura, Kazuyuki Ueno, Kenichi Watanabe

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Aims Sustained glucagon infusion increases hepatic glucose production, but this effect is transient due to hypothalamic glucagon signaling. In hypoglycemia, glucagon acts as a major defense to sustain the blood glucose level and this raises the question regarding glucagon signaling associated glucose production in prolonged fasting hypoglycemia. In this study, we investigated the proteins associated with hypothalamic glucagon signaling and liver gluconeogenesis during fasting hypoglycemia. Main methods 8-9 week old, male C57BL6/J mice were fasted for 4, 8, 12, 18, 24, 30, 36 or 42 h. In the hypothalamus, we investigated glucagon signaling by analyzing the glucagon receptor and its downstream protein, peroxisome proliferator-activated receptor-gamma coactivator 1 (PGC-1) expression. In the liver, we investigated gluconeogenesis by analyzing p-protein kinase A (PKA)Ser/Thr substrate and phosphoenolpyruvate carboxykinase - cytosolic (PEPCK-C) expression using the western blotting technique. Key findings The elevated or trended higher hypothalamic glucagon receptor and PGC-1 expressions at 18 and 42 h were correlated with the attenuated liver p-PKASer/Thr substrate expression. The attenuated hypothalamic glucagon receptor and PGC-1 expressions at 12, 24, 30 and 36 h were correlated with the elevated or trended higher liver p-PKASer/Thr substrate expression. Significance The hypothalamic glucagon signaling during fasting hypoglycemia might have been modulated by circadian rhythm and this possibly attenuates the liver p-PKASer/Thr substrate to modify the gluconeogenesis pathway. This mechanism will help to understand the hyperglucagonemia associated complications in diabetes.

Original languageEnglish (US)
Pages (from-to)118-123
Number of pages6
JournalLife sciences
Volume153
DOIs
StatePublished - May 15 2016

Keywords

  • Fasting
  • Glucagon
  • Gluconeogenesis
  • Hypoglycemia
  • Hypothalamus
  • Liver

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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