Related Experiment Videos
GH replacement fails to improve ventricular function in hypophysectomized rats with myocardial infarction
Y T Shen1, R T Wiedmann, J J Lynch
1Department of Pharmacology and Clinical Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
The American Journal of Physiology
|November 1, 1996
Summary
Growth hormone (GH) replacement effectively prevents body weight loss after myocardial infarction (MI) in rats. However, it does not improve cardiac function in moderate or severe MI models.
Area of Science:
- Cardiology
- Endocrinology
- Regenerative Medicine
Background:
- Myocardial infarction (MI) often leads to cardiac dysfunction and detrimental physiological changes.
- Growth hormone (GH) plays a role in tissue growth and repair, but its effects on cardiac function post-MI are not fully understood.
- Understanding GH's impact is crucial for developing novel therapeutic strategies for heart disease.
Purpose of the Study:
- To investigate whether growth hormone (GH) replacement therapy improves cardiac function in rats following myocardial infarction (MI).
- To assess the effects of both physiological GH replacement and excess GH treatment on cardiac performance and infarct size.
Main Methods:
- GH-deficient hypophysectomized rats with moderate MI received recombinant rat GH or vehicle for 3 weeks.
- Serum insulin-like growth factor I levels were measured.
- Cardiac function was assessed using hemodynamic measurements and responses to pharmacological stimulation; infarct size and body weight were also evaluated.
- A separate cohort of rats with larger infarcts received excess GH treatment for 4 weeks to assess severe cardiac dysfunction.
Main Results:
- GH treatment significantly increased serum insulin-like growth factor I levels and prevented body weight loss post-MI.
- Neither GH replacement in moderate MI nor excess GH in severe MI rats showed significant improvements in cardiac function (e.g., LV systolic pressure, contractility) or infarct size compared to vehicle groups.
- Hemodynamic parameters and infarct size remained similar between GH-treated and vehicle-treated groups in both study models.
Conclusions:
- While GH treatment effectively mitigates body weight loss after MI in rats, it does not appear to preserve or improve cardiac function.
- Neither physiological GH replacement nor excess GH administration demonstrates a significant therapeutic role in improving cardiac performance following myocardial infarction.
- Further research may be needed to explore alternative mechanisms or dosages for potential cardiac benefits of GH.