Combination of chronic stress with fructose diet increases AMP-activated protein kinase phosphorylation and affects agouti-related protein and proopiomelanocortin expression in the hypothalamus of male Wistar rats

Acta Biochim Pol. 2022 Jul 25;69(3):647-655. doi: 10.18388/abp.2020_6075.

Abstract

Appetite regulation in the hypothalamus is dependent on hormonal signals from the periphery, such as insulin and leptin, and can be modulated by both sugar-rich diet and stress. Our aim was to explore the effects of 9-week feeding with 20% fructose solution combined with 4-week chronic unpredictable stress, on appetite-regulating neuropeptides and modulatory role of leptin and insulin signalling in the hypothalamus of male Wistar rats. Energy intake, body mass and adiposity, as well as circulatory leptin and insulin concentrations were assessed. Hypothalamic insulin signalling was analysed at the level of glucose transporters, as well as at the protein level and phosphorylation of insulin receptor, insulin receptor supstrate-1, Akt and ERK. Phosphorylation of AMP-activated protein kinase (AMPK), level of protein tyrosine phosphatase 1B (PTP1B) and expression of leptin receptor (ObRb) and suppressor of cytokine signalling 3 (SOCS3) were also analysed, together with the expression of orexigenic agouti-related protein (AgRP) and anorexigenic proopiomelanocortin (POMC) neuropeptides. The results revealed that stress decreased body mass and adiposity, blood leptin level and expression of ObRb, SOCS3 and POMC, while combination with fructose diet led to marked increase of AgRP, associated with AMPK phosphorylation despite increased plasma insulin. Reduced Akt, enhanced ERK activity and elevated PTP1B were also observed in the hypothalamus of these animals. In conclusion, our results showed that joint effects of fructose diet and stress are more deleterious than the separate ones, since inappropriate appetite control in the hypothalamus may provide a setting for the disturbed energy homeostasis in the long run.

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Agouti-Related Protein / metabolism
  • Agouti-Related Protein / pharmacology
  • Animals
  • Cytokines / metabolism
  • Diet
  • Fructose / adverse effects
  • Fructose / metabolism
  • Glucose / metabolism
  • Hypothalamus / metabolism
  • Insulin
  • Leptin
  • Male
  • Neuropeptides* / metabolism
  • Neuropeptides* / pharmacology
  • Phosphorylation
  • Pro-Opiomelanocortin* / metabolism
  • Pro-Opiomelanocortin* / pharmacology
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1 / metabolism
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1 / pharmacology
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Rats, Wistar
  • Receptor, Insulin / metabolism
  • Receptors, Leptin / metabolism

Substances

  • AGRP protein, rat
  • Agouti-Related Protein
  • Cytokines
  • Insulin
  • Leptin
  • Neuropeptides
  • Receptors, Leptin
  • Fructose
  • Pro-Opiomelanocortin
  • Receptor, Insulin
  • Proto-Oncogene Proteins c-akt
  • AMP-Activated Protein Kinases
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Glucose