κ-Opioid receptor stimulation reduces palmitate-induced apoptosis via Akt/eNOS signaling pathway

Area of Science:

• Endothelial Cell Biology
• Molecular Pharmacology
• Cardiovascular Research

Background:

• Palmitate exposure induces apoptosis in human umbilical vein endothelial cells (HUVECs).
• The role of κ-opioid receptor (κ-OR) in mitigating palmitate-induced endothelial cell apoptosis is not well understood.

Purpose of the Study:

• To investigate the hypothesis that κ-opioid receptor (κ-OR) stimulation reduces palmitate-induced HUVEC apoptosis.
• To elucidate the underlying molecular mechanisms involving the PI3K/Akt/eNOS signaling pathway.

Main Methods:

• HUVECs were treated with sodium palmitate, with or without the κ-OR agonist U50,488H and antagonist nor-BNI.
• Cell viability, apoptosis rates, and protein expression/phosphorylation (Akt, eNOS, caspase 3) were assessed.
• Specific inhibitors for PI3K, Akt, eNOS, and siRNAs targeting κ-OR and Akt were employed.

Main Results:

• Sodium palmitate decreased HUVEC viability and increased apoptosis, effects reversed by U50,488H.
• U50,488H treatment restored Akt and eNOS phosphorylation and reduced caspase 3 expression, an effect blocked by nor-BNI or pathway inhibitors.
• κ-OR and Akt siRNA abolished U50,488H-mediated protective effects on apoptosis markers.

Conclusions:

• κ-opioid receptor (κ-OR) stimulation demonstrates a significant anti-apoptotic effect against palmitate-induced endothelial cell damage.
• The protective mechanism is primarily mediated through the activation of the PI3K/Akt/eNOS signaling cascade.
• κ-OR represents a potential therapeutic target for conditions involving palmitate-induced endothelial dysfunction.