孕期咖啡因暴露导致子代成年雌性大鼠代谢综合征易感及发生机制

Prenatal caffeine exposure induces high susceptibility to metabolic syndrome in offspring adult female rats and possible mechanism

目的观察经历出生后早期追赶性生长和后期慢性应激的孕期咖啡因暴露(PCE)子代成年雌性大鼠代谢综合征(MS)的易感现象并探讨其发生机制。方法 Wistar大鼠于孕11 d每天ig给予咖啡因120 mg·kg^(-1)至分娩,子代雌性大鼠4周龄(PW4)~PW24给予高脂饮食,并于PW38~PW40给予2周不可预知性慢性应激,分别检测血糖及血清促肾上腺皮质激素释放激素、皮质酮、胰岛素、甘油三酯、总胆固醇、低密度脂蛋白(LDL-C)和高密度脂蛋白(HDL-C)水平。实时定量PCR技术检测肾上腺组织的甾体合成急性调节蛋白、P450侧链裂解酶、3β-羟类固醇脱氢酶、类固醇11β-羟化酶和类固醇21β-羟化酶,以及肝组织的胰岛素受体、胰岛素受体底物2和葡萄糖转运体2(GLUT2)m RNA表达。HE染色观察肾上腺、胰腺和肝组织形态。结果 PCE子代雌性大鼠PW1时体质量为(10.5±1.0)g,显著低于对照组(13.9±2.8)g(P<0.01),这种低体质量持续至PW40(P<0.05,P<0.01),但体质量增长率在PW4~PW16处于高水平(P<0.05,P<0.01)。同时,血糖〔(5.9±0.3)mmol·L^(-1)〕水平和血清胰岛素水平〔(100±31)m U·L^(-1)〕、胰岛素抵抗指数(26.3±5.7)和血清LDL-C水平〔(0.55±0.05)mmol·L^(-1)〕及LDL-C/HDL-C比值(0.87±0.11)分别高于对照组〔血糖:(4.3±0.3)mmol·L^(-1);血胰岛素:(45±4)m U·L^(-1);胰岛素抵抗指数:8.3±0.9;LDL-C:(0.38±0.04)mmol·L^(-1);LDL-C/HDL-C比值∶0.66±0.07〕(P<0.05,P<0.01)。PCE组肝组织GLUT2 m RNA表达低于对照组(P<0.05)。光镜下可见,PCE组肾上腺束状带变薄,胰腺胰岛面积变小,而肝组织形态无明显变化。结论 PCE子代成年雌性大鼠MS易感性增加,主要表现为以高血糖和高胰岛素血症为特征的胰岛素抵抗、脂代谢紊乱、多脏器结构及功能异常,其发生与下丘脑-垂体-肾上腺轴相关的宫内神经内分泌代谢编程紊乱有关。

OBJECTIVE To observe the increased susceptibility to metabolic syndrome （MS） in offspring adult female rats which experienced prenatal caffeine exposure （PCE） and underwent early postnatal catch-up growth and late chronic stress, and to explore the underlying mechanism. METHODS Starting from gestational day 11, pregnant Wistar rats were intragastrically administered with caffeine at the dose of 120 mg. kg-1 per day until delivery. The female offspring rats were fed a high-fat diet from postnatal week 4 （PW4） to PW24, and then exposed to two weeks of unpredictable chronic stress at PW38-PW40. Blood glucose and serum adrenocorticotropic hormone, corticosterone, insulin, triglycer- ides, total cholesterol, low-density lipoprotein-cholesterol （LDL-C） and high-density lipoprotein-cholesterol （HDL-C） levels were detected. Meanwhile, the mRNA expression of adrenal steroidogenic acute regulatory protein, P450 side-chain cleavage enzyme, 315-hydroxysteroid dehydrogenase, steroid 1115-hydroxy- lase, steroid 2115- hydroxylase, hepatic insulin receptor, insulin receptor substrate 2 and glucose trans- porter 2 （GLUT2） were examined by real-time quantitative PCR. The morphological changes of the adrenal gland, pancreas and liver were observed using hematoxylin-eosin staining. RESULTS Compared with control group [（13.9±2.8） g], the body mass of the PCE offspring female rats at PW1 E（10.5±1.0） g） was significantly lower （P〈0.01）, which lasted until PW40 （P〈0.05, P〈0.01）. However, the gain rate of body mass was higher in the PCE group at PW4-PW16 （P〈0.05, P〈0.01）. Levels of blood glucose （5.9±0.3） mmol. L-1） and serum insulin C（100±31） mU. L-l）, the insulin resistance index （26.3± 5.7）, LDL-C [（0.55＋0.05） mmol-L-1 level and LDL-C/HDL-C ratio （0.87±0.11） were increased compared with （4.3±0.3） mmol. L-1, （45±4） mU-L-1, 8.3~0.9, （0.38＋0.04） mmol. L-1 and 0.66±0.07 in the control group, respectively （P〈0.05, P〈0.01）. The mRNA expression of hepatic GLUT2 in the PCE group was lower than in the control group （P〈0.05）. Furthermore, the thicknesses of the adrenal zona fasciculata was re- duced and the area of pancreatic islets became smaller, but there was no significant change in liver morphology. CONCLUSION PCE offspring adult female rats display high susceptibility to MS, which is mainly manifested as insulin resistance, characterized by hyperglycemia and hyperinsulinemia, lipid metabolism disorder and structural and functional abnormalities of multiple organs. The mechanism is possibly related to the disorder of hypothalamic-pituitary-adrenal axis-associated neuroendocrine metabolic programming.