Physiological or pathological--a role for relaxin in the cardiovascular system?

Area of Science:

• Endocrinology and Cardiovascular Science

Background:

• Relaxin (RLX) is a 6kDa polypeptide hormone with endocrine and paracrine functions, targeting multiple tissues including the cardiovascular system.
• Humans possess three RLX genes (H1, H2, H3), with H2 RLX being the predominant circulating form. Rodents have relaxin-1 (H2 equivalent) and relaxin-3 (H3 equivalent).
• The RLX receptor, LGR7, is found in the heart, confirming it as a target organ for RLX (H2).

Purpose of the Study:

• To investigate the limited evidence for endogenous RLX production within the cardiovascular system.
• To clarify the physiological effects of RLX on cardiac function.
• To address the controversy surrounding RLX's role, particularly its elevated levels in heart failure.

Main Methods:

• Review of existing literature on relaxin, its receptor LGR7, and cardiovascular effects.
• Analysis of studies investigating RLX expression and function in cardiac tissues.
• Examination of data on RLX serum concentrations and cardiac expression in pathological conditions.

Main Results:

• Evidence for RLX production within the cardiovascular system remains limited.
• Few studies have definitively identified the physiological impacts of RLX on heart function.
• Elevated serum RLX and cardiac expression are observed in chronic heart failure and cardiomyopathy models.

Conclusions:

• The precise role of RLX in cardiovascular physiology requires further elucidation.
• Current findings suggest RLX may serve as a marker for cardiovascular pathology rather than normal function.
• Additional research is needed to understand RLX's endogenous production and specific cardiac effects.