探讨β3肾上腺素能受体（β3-AR）在慢性心力衰竭（CHF）大鼠心肌中的作用及其与磷脂酰肌醇3激酶（PI3K）-蛋白激酶B（Akt）的关系。

将16只Wistar大鼠分为对照组和阿霉素组，每组各8只。阿霉素组大鼠每周腹腔注射阿霉素2次（每次1 mg/kg），对照组注射等量等渗NaCl溶液（每次1 mL/kg），分别注射8周后再继续饲养3周，第11周结束后将所有大鼠称重并直接处死。采用酶联免疫吸附测定法检测两组大鼠血浆氨基末端脑钠肽前体（NT-proBNP）和一氧化氮水平，同时采用苏木素-伊红（HE）染色观察两组大鼠心肌组织。分别采用实时荧光定量PCR和Western-blotting法检测两组大鼠心室肌β3-AR、PI3K、Akt信使RNA（mRNA）及β3-AR、PI3K、磷酸化Akt（p-Akt）、Akt蛋白表达水平。

实验结束时，阿霉素组大鼠体质量显著低于对照组大鼠[（275 ± 6）g vs.（353 ± 5）g，t = 9.571，P < 0.001]，而血浆NT-proBNP水平较对照组显著升高[（2 158 ± 69）ng/L vs.（1 071 ± 59）ng/L，t = 11.969，P < 0.001]。HE染色结果显示，对照组大鼠心肌结构清晰，肌纤维排列整齐，连接紧密，无细胞水肿与坏死；而阿霉素组大鼠心肌细胞条纹不清，心肌纤维排列紊乱，细胞水肿，间隙增宽，炎症细胞浸润，少量不同程度的斑片状坏死。阿霉素组大鼠心肌β3-AR（t = 2.418、6.965，P均< 0.05）、PI3K（t = 3.704、4.926，P均< 0.05）mRNA和蛋白表达水平以及p-Akt（t = 7.210，P < 0.001）蛋白表达水平均较对照组显著升高。Pearson相关分析结果显示，心肌β3-AR（r = 0.749、0.803，P均< 0.05）mRNA和蛋白水平与PI3K，β3-AR蛋白（r = 0.748，P = 0.001）与p-Akt蛋白均呈正相关。

在CHF大鼠中，β3-AR水平显著升高且与PI3K和p-Akt密切相关，β3-AR可能通过PI3K-Akt信号通路对阿霉素所致CHF产生影响。

To investigate the role of beta3-adrenergic receptor (β3-AR) in the myocardium of chronic heart failure (CHF) and its association with phosphatidylinositol 3 kinase (PI3K)-protein kinase B (Akt).

Totally 16 Wistar rats were divided into a control group and a doxorubicin group, with eight rats in each group. Rats in the doxorubicin group were intraperitoneally injected with doxorubicin twice a week (1 mg/kg each time), and rats the control group were injected with the same amount of isosmotic NaCl solution (1 mL/kg each time). Kept for three weeks after eight weeks of injection, all rats were weighed and killed directly. The plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) and nitric oxide of rats in the two groups were detected by enzyme-linked immunosorbent assay, and the myocardial conditions were observed by hematoxylin-eosin (HE) staining. The messenger RNA (mRNA) levels of β3-AR, PI3K and Akt in the ventricular muscle were determined by real-time fluorescence quantitative PCR, and the protein levels of β3-AR, PI3K, phospho-Akt (p-Akt) and Akt were detected by Western-blotting.

At the end of the experiment, the body mass of rats in the doxorubicin group was significantly lower than that in the control group [(275 ± 6) g vs. (353 ± 5) g, t = 9.571, P < 0.001], while the plasma NT-proBNP level was significantly higher [(2 158 ± 69) ng/L vs. (1 071 ± 59) ng/L, t = 11.969, P < 0.001]. HE staining showed that the myocardial structure of rats in the control group was clear, the muscle fibers were neatly arranged and tightly connected, and there was no cell edema and necrosis. The myocardial cells of rats in the doxorubicin group were not striped, the myocardial fibers were disordered, and there was cell edema, gap widening, inflammatory cell infiltration and a small amount of patchy necrosis. The mRNA and protein levels of myocardial β3-AR (t = 2.418, 6.965; both P < 0.05), PI3K (t = 3.704, 4.926; both P < 0.05) and the protein levels of p-Akt (t = 7.210, P < 0.001) in the doxorubicin group were significantly higher than those in the control group. Pearson correlation analysis showed that the mRNA and protein levels of myocardial β3-AR (r = 0.749, 0.803; both P < 0.05) were positively correlated to PI3K, and the protein level of β3-AR was positively correlated to p-Akt protein (r = 0.748, P = 0.001).

In the rats with CHF, the levels of β3-AR are significantly elevated and closely related to PI3K and p-Akt, which may affect doxorubicin-induced CHF through the PI3K-Akt signaling pathway.