Changes in expression of adrenomedullin in the myocardium of streptozotocin-induced diabetic rats.
BACKGROUND
Adrenomedullin is a potent vasodilating peptide and involved in many cardiovascular diseases. However, whether adrenomedullin is involved in the pathogenesis of diabetic cardiomyopathy is still unknown. Our aim was to characterize the expression pattern of adrenomedullin in the myocardium of streptozotocin-induced diabetic rats.


METHODS
The weight, blood glucose, and urine glucose of 20 streptozotocin-induced diabetic rats were measured before and after model induction in the diabetic and control groups. The alteration of the adrenomedullin expression was explored in the left ventricular myocardium in both groups by immunohistochemistry. Changes in heart ultrastructure were also analyzed by using hemotoxylin and eosin staining and transmission electron microscopy. All data were analyzed by the independent samples t test.


RESULTS
The data of weight, blood glucose, and urine glucose had no significant difference between the control and the diabetic groups before animal model induction. Four weeks after the induction of diabetes, the differences between the two groups in weight, blood glucose, and urine glucose were distinct. When compared with the control group, the diabetic group showed ultrastructural changes including hypertrophy, fibrosis, myofibrillar disarrangements, mitochondrial disruption, and increase in nuclear membrane invaginations. A significant decrease of adrenomedullin expression was also observed in cardiac myocytes of the diabetic rats (P < 0.01).


CONCLUSIONS
Our study provides experimental evidence that hyperglycemia could damage cardiac myocytes. Down-regulation of cardioprotective peptide adrenomedullin in the myocardium of streptozotocin-induced diabetic rats may contribute to the diabetic cardiomyopathy and left ventricular dysfunction.
He
Rong-xin
RX
Department of Orthopaedics, Second Affiliated Hospital of Medical School, Zhejiang University, Hangzhou 310009, China.
Gu
Chuan-long
CL
Shen
Fang
F
Zhang
Xiao-ming
XM
D053607:Adrenomedullin / Q000032:analysis*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D009202:Cardiomyopathies / Q000209:etiology; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D009206:Myocardium / Q000737:chemistry* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin
D001786:Blood Glucose; D053607:Adrenomedullin; D013311:Streptozocin