Estrus cycle: influence on cardiac function following trauma-hemorrhage

Area of Science:

• Physiology
• Cardiovascular Biology
• Endocrinology

Background:

• Trauma-hemorrhage (T-H) depresses cardiac function in males, but not in proestrus (PE) females.
• The influence of the female estrus cycle on cardiac response to T-H is not well understood.

Purpose of the Study:

• To investigate the impact of different estrus cycle phases on cardiac function following T-H and resuscitation in female rats.
• To determine if PE females exhibit preserved cardiac function and identify underlying molecular mechanisms.

Main Methods:

• Five groups of female rats (PE, estrus, metestrus, diestrus, ovariectomized) underwent sham operation or T-H.
• Cardiac function was assessed 2 hours post-T-H.
• Cardiomyocyte IL-6 and NF-kappaB expression were measured via Western blotting.
• Plasma IL-6, estradiol, and progesterone levels were quantified using ELISA/EIA kits.

Main Results:

• Cardiac function was depressed in diestrus, estrus, metestrus, and ovariectomized groups but maintained in the PE group after T-H.
• PE females exhibited the highest plasma estrogen levels.
• Plasma and cardiomyocyte IL-6 levels, along with cardiomyocyte NF-kappaB expression, were significantly increased in non-PE groups but attenuated in the PE group following T-H.

Conclusions:

• The estrus cycle significantly influences cardiac function recovery after trauma-hemorrhage.
• Proestrus phase confers a protective effect on cardiac function post-T-H, likely mediated by a downregulation of the NF-kappaB-dependent cardiac IL-6 pathway.