Phoenixin-14: detection and novel physiological implications in cardiac modulation and cardioprotection

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Molecular Biology

Background:

• Phoenixin-14 (PNX) is a newly discovered peptide found in the hypothalamus and heart.
• PNX can cross the blood-brain barrier, suggesting potential peripheral roles.
• Nesfatin-1, co-expressed with PNX, is known for its anorexic and cardioactive properties.

Purpose of the Study:

• To quantify PNX expression in the rat heart.
• To investigate the influence of PNX on myocardial function under basal and ischemia/reperfusion (I/R) conditions.
• To explore PNX's effects in the context of metabolic disorders like obesity.

Main Methods:

• Enzyme-Linked Immunosorbent Assay (ELISA) for PNX quantification in hypothalamus and heart.
• Isolated Langendorff perfused rat heart model to assess PNX effects on cardiac function.
• Immunoblotting to analyze changes in key signaling pathway phosphorylation (Erk1/2, Akt, eNOS).

Main Results:

• PNX was detected in both hypothalamus and heart; plasma levels increased post-meal in normal rats.
• Exogenous PNX reduced contractility and relaxation but did not affect coronary pressure or heart rate.
• PNX administration post-ischemia conferred cardioprotection, reducing infarct size and improving systolic recovery, activating RISK/SAFE cascades and inhibiting apoptosis, effects also seen in obese rat hearts.

Conclusions:

• This study provides the first evidence of PNX's peripheral activity and direct cardiomodulatory effects.
• PNX exhibits significant cardioprotective properties against ischemia/reperfusion injury.
• The peptide's beneficial actions are maintained even in the presence of metabolic disorders, suggesting therapeutic potential.