Effect Of Estrogen On Cardiovascular Function Of Broilers And Its Mechanism

Sudden death syndrome (SDS) is a cardiovascular disease of broilers. Gender difference was discovered in the sensitivity of SDS. The incidence rate of SDS in male broilers was significantly higer than that in female broilers, while the cardiovascular function of female broilers was better than that of male broilers. In previous research, Estrogen was known to play a permissive role in cardioprotection of mammals, which is a key factor lead to the gender difference of cardiovascular disease in human. No research was focused on the effect of estrogen on cardiovascular system of broilers before. This study use ovariectomized broilers to investigated the effects of estrogen on cardiovascular system of broilers, and the role of estrogen receptor in this process.1. Broilers were ovariectomized at 7 day-old. Ovariectomized broilers were supplemented with 17-β-estradiol (E2) or both selective estrogen receptor antagonist ICI 182,780 (ICI) and E2. ECG was monitored, serum enzymes activities, lipids and electrolyte levels were detected at 28 day-old.2. Heart rate, serum aspartate amino transferase (AST), lactate dehydrogenase (LDH) and creatine kinase (CK) levels increased after ovariectomy, suggesting the cardiac injury occurred. Estrogen treatment inhibited the cardiac injury induced by ovariectomy, suggesting estrogen had protective effect on cardiac function in broilers. The effects of estrogen were suppressed if experimental broilers were treated with estrogen receptor antagonist, suggesting that the effects of estrogen on cardiac function in broilers were estrogen receptor-mediated.3. Estrogen replacement prevented the serum cholesterol, triglycerides, and LDL-C levels from increasing by ovariectomy. Moreover, the effects of estrogen were attenuated after estrogen receptor was blocked, suggesting the effect of estrogen on lipid metabolism was also estrogen receptor-mediated.4. Hearts for histopathological studies were obtained from each group of experimental broilers. No significant pathological changes were observed by light microscopy. 5. Conclusion:Estrogen improved the cardiovascular function and lipid metabolism of broilers. This effect was probably mediated by estrogen receptor.