The effects of intra-uterine growth retardation and postnatal undernutrition on onset of puberty in male and female rats

The nutritional status, prenatally and early postnatally, plays a critical role in postnatal growth and development. Early malnutrition may change the original programming of organs, especially those in developmental phases, which can result in long-term changes in metabolism. The association between a low birth weight and the increased risk on type 2 diabetes, hypertension and cardiovascular disease is well known. In the present study we investigated whether intrauterine malnutrition or direct postnatal food restriction affects the onset of puberty in male and female rats. Intrauterine growth retardation (IUGR) was induced by uterine artery ligation on day 17 of gestation and postnatal food restriction (FR) by litter-enlargement to 20 pups per mother from day 2 after birth until weaning (24 d). Both models of malnutrition resulted in a persistent growth failure postnatally. The parameter of the onset of puberty was balano-preputial-separation (BPS) in the male rat and vaginal opening (VO) in the female rat. In both male IUGR (n = 26) and FR (n = 20) rats, the age at BPS was significantly delayed, with 48.1 +/- 1.9 d (p < 0.0001) and 50.4 +/- 2.9 d (p < 0. 0001), respectively, compared with controls (n = 30) with 45.8 +/- 1.4 d. In female IUGR rats (n = 37) the age at VO was significantly delayed, with 37.4 +/- 2.7 d (p < 0.04) compared with 36.1 +/- 1.5 d in controls (n = 23), but not in female FR rats (n = 18) with 36.5 +/- 2.2 d. Weight at onset of puberty did not differ between male IUGR and control rats, 194.5 +/- 20.0 g and 201.7 +/- 16.8 g, respectively, but was significantly lower in male FR rats with a weight of 175.6 +/- 17.5 g (p < 0.0001). In female IUGR as well as in female FR rats, weight at onset of puberty was significantly lower compared with controls: weight in IUGR 106.1 +/- 13.1 g (p < 0.001), weight in FR 85.3 +/- 7.6 g (p < 0.0001) and weight in controls 116.9 +/- 9.3 g. We conclude that early malnutrition, during late gestation or direct postnatally, results in a delayed onset of puberty in IUGR and FR male rats and in IUGR female rats, but not in FR female rats. The onset of puberty in these growth retarded rats as well as in controls does not depend on the achievement of a certain, crucial weight. The perinatal period appears to be a "critical time period" for the maturational process of pubertal development.     

Effect of Nomega-nitro-L-arginine methyl ester-induced intrauterine growth restriction on postnatal lung growth in rats

Infants with intrauterine growth restriction (IUGR) are at high risk for morbidity and mortality. Preeclampsia, one of the leading causes of IUGR, begins during the canalicular phase of lung development. The aim of our study was to determine whether induced IUGR was responsible for abnormal lung development in rat pups. We randomized pregnant Sprague-Dawley rats to daily gavage with either the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME; n = 5, 50 mg . kg(-1) . d(-1)) or pure water (n = 6). The pups were weighed at birth and on postnatal days 7 and 14. At each of these time points, pups were killed and their lung growth was assessed on the basis of lung volume and light-microscopy morphometric data. At birth, body weight, total alveolar surface area, and alveolar surface density were significantly decreased and alveolar size was significantly increased in the L-NAME group, compared with the control group. On day 7, body weight was similar in the two groups, and the only significant difference was smaller total alveolar surface area in the L-NAME group. On day 14, neither body weight nor lung morphometric parameters were significantly different between the L-NAME group and the controls. These results suggest that postnatal catch-up growth may completely correct the lung development disorders present at birth in IUGR pups, in parallel with the catch-up body weight gain.     

Body mass index, body composition, and leptin at onset of puberty in male and female rats after intrauterine growth retardation and after early postnatal food restriction

In this study we examined the body composition at onset of puberty in intrauterine growth retarded (IUGR), postnatal food restricted (FR), and control male and female rats. IUGR was induced by ligation of the uterine artery on d 17 of gestation and FR by litter enlargement to 20 pups per mother from d 2 after birth until weaning (d 24). We defined onset of puberty as balanopreputial separation in male rats and vaginal opening in female rats. We calculated body mass index, measured body composition with dual-energy x-ray absorptiometry, and measured leptin concentrations in serum. It was reported previously that early malnutrition, either during late gestation or immediately postnatally, results in a delayed onset of puberty in IUGR and FR male rats and in IUGR female rats, but not in FR female rats. In IUGR male rats at balanopreputial separation and in IUGR female rats at vaginal opening no differences were found in body mass index, body composition, and leptin levels compared with controls. FR male rats had a significantly lower percentage of fat and serum leptin concentrations at balanopreputial separation. FR female rats had a significantly lower body mass index, percentage of fat, and serum leptin concentrations at vaginal opening. We conclude that the onset of puberty in the rat is not dependent on a certain percentage of body fat or a certain threshold of circulating levels of leptin and that food deprivation during different "critical" time periods around birth results in different effects in later life.     

生长追赶宫内发育迟缓大鼠早期糖脂代谢及脂肪细胞功能的改变

目的：探讨生长追赶宫内发育迟缓(IUGR)大鼠早期糖脂代谢及脂肪细胞功能的改变。方法：母孕期饥饿法建立IUGR大鼠模型。禁食组仔鼠作为生长追赶IUGR模型组（IUGR组）,正常喂养仔鼠作为对照组（AGA组）。12周龄时检测血浆甘油三酯（TG）、胆固醇（TC）、低密度脂蛋白-C（LDL-C）、高密度脂蛋白-C（HDL-C）以及脂联素、促酰化刺激蛋白（ASP）的水平。隔日行糖耐量试验（OGTT）,检测血浆葡萄糖和胰岛素水平,计算胰岛素抵抗指数（IRI）。随后仔鼠断头处死,共聚焦显微镜下观察免疫荧光染色的成熟脂肪细胞中葡萄糖转运体-4（GLUT-4)的表达。结果：12周末时IUGR组大鼠体重、BMI显著高于AGA组（均P<0.01）,血TG、TC、LDL-C水平显著高于AGA组,HDL-C水平明显低于AGA组（P<0.05）。OGTT中IUGR组注射葡萄糖后各时间点血糖水平均高于AGA组（P<0.05）,IRI值亦显著增高（P<0.05）。与AGA组比较,IUGR组ASP水平明显升高(P<0.05）,而脂联素水平显著降低（P<0.05）。IUGR大鼠成熟脂肪组织中GLUT-4在基础状态和不同浓度胰岛素刺激下的表达水平与AGA组相比均明显降低（P<0.05）。结论：IUGR大鼠生后发生明显的生长追赶,12周时即存在高血脂、高血糖及胰岛素抵抗。脂肪细胞分泌功能的异常和脂肪组织GLUT-4表达水平的降低可能参与了生长追赶IUGR大鼠胰岛素抵抗的形成。     

Evaluation of a core battery of tests for detecting behavioral dysfunction of rat offspring induced by retinoic acid: Collaborative work II of the Japanese behavioral teratology committee

ABSTRACT  The Japanese Behavioral Teratology Meeting, a satellite meeting of the Japanese Teratology Society, proposed a core battery of tests to detect behavioral teratogens in animals in 1992. The core battery consists of examining maternal body weight, offspring weight, external anomalies, viability, preweaning landmarks of physical development (pinna, incisor and eyelids), preweaning reflex tests (surface righting, negative geotaxis and mid-air righting), an open-field test at 5 weeks of age, a water-filled multiple T-maze (Biel-type water maze) test at 6 weeks, a shuttlebox test at 7 weeks and brain weight at termination on postnatal day 56. In order to evaluate the detectability of behavioral dysfunction in rat offspring by this core battery, the first collaborative study was carried out in 1993 using phenytoin. The present, second collaborative study using retinoic acid (RA) was performed in twenty-eight laboratories to further evaluate the proposed core test battery. Pregnant SD rats received 5 mg/kg RA orally from days 14 to 16 of gestation, and postnatal development of their offspring was evaluated. The effects of RA on offspring were detected as lower viability, increased incidence of minor anomalies in the paw and nail, delayed pinna detachment, negative geotaxis and air righting, and less frequent rearing and grooming behaviors in the open-field test. However, no effects were observed in the Biel-type maze and shuttlebox tests. These results suggest that our proposed core battery of tests is useful as a screening method to detect postnatal development disorders, including behavioral dysfunction, in SD rat offspring exposed to RA in utero.     

Effects of antenatal uteroplacental hypoperfusion on neonatal microvascularisation and excitotoxin sensitivity in mice

Vascular intrauterine growth restriction (IUGR) occurs in about 5% of pregnancies and may reduce the incidence of periventricular leukomalacia in preterm newborns. We evaluated neonatal excitotoxicity in a murine model of vascular IUGR involving unilateral uterine ligation on embryonic day (E)13.5. Birth weight was significantly decreased in the ligation group compared with the sham group (p < 0.001). VEGFs, VEGF receptors (VEGFRs), and NMDA receptor subunit mRNAs in brain extracts were assayed using quantitative RT-PCR. Ligation was associated with increased mRNAs for the vascular marker PECAM-1 on postnatal day (PD)2 and VEGFR-3 on PD2 and PD10, contrasting with decreased VEGFA and VEGFC on PD10. Microvessel density was increased on PD7. Ligated and sham pups received intracerebral ibotenate (NMDA agonist) on PD2 or PD10. Cortical and white matter (WM) lesions after 5 d were reduced in ligated versus sham pups injected on PD2 (p < 0.001 and p < 0.01, respectively); this effect persisted on PD42 (p < 0.01 and p < 0.05, respectively). With ibotenate on PD10, lesions were exacerbated after 5 d in the ligated group in the cortex (p < 0.05) and WM (p < 0.05) and on PD42 in the cortex (p < 0.05). In conclusion, vascular IUGR offered only transient protection against neonatal excitotoxic lesions, possibly via angiogenesis.     

IUGR大鼠胰岛素样生长因子与小肠及体格发育关系的研究

目的：生后早期的生长主要受营养的调控,营养物质-胰岛素-胰岛素样生长因子(IGF)轴在胎儿宫内发育迟缓(IUGR)生长追赶及胃肠发育中起着重要的作用,而胃肠发育又与营养物质的吸收、生长追赶关系密切。目前国内有关IUGR出生时小肠发育状况报道甚少,且仅限于IUGR出生时胃肠形态结构的观察。该研究探讨生后早期不同蛋白质和热卡水平的营养干预如何调控IGF系统及影响IUGR大鼠的小肠发育和体格生长追赶,并追踪至成年期。方法：采用孕母饥饿法建立IUGR模型。64只IUGR新生鼠随机分为4组：IUGR正常饮食组(SC组),饮食中蛋白含量20%;IUGR高蛋白组(SH组),饮食中蛋白含量占30%;IUGR低蛋白组(SL组),饮食中蛋白含量为10%;IUGR高热卡组(SA组),饮食中热卡较其它组高20%。16只正常新生鼠为正常对照组(C组)予以正常饮食。幼鼠3周断乳后继续予原饮食模式1周,第4周起各组均予正常饮食喂养。分别于出生时及生后第4周、12周测定各组大鼠的血清IGF-1、胰岛素生长因子结合蛋白-3(IGFBP-3)浓度及体重、身长和小肠重量、长度。结果：IUGR大鼠虽然宫内营养不良,但SH组及SA组呈快速小肠发育和体格生长追赶伴IGFs水平明显升高,其中4周时SH组IGFs水平显著高于其余各组(P0.05)。SL组4周和8周的体重、身长、小肠长度和重量均低于其它4组(P0.05)。结论：4周时血清IGF-1是反映生长追赶的灵敏指标,与小肠和体格的生长追赶呈正相关,至成年期这种相关性消失。     

Ghrelin及受体GHSR表达变化与宫内发育受限仔鼠追赶生长的关系

目的：了解Ghrelin及生长激素释放促分泌素受体（GHSR）表达变化与宫内发育受限（IUGR）仔鼠追赶生长的关系。方法：采用妊娠期食物限制法建立IUGR大鼠模型,孕鼠分娩后,获得限食小于胎龄（SGA）仔鼠和限食适于胎龄（AGA）仔鼠为实验组,不限食适于胎龄（AGA）仔鼠为对照组。于0、20、40日龄取胃底和下丘脑组织,实时荧光定量PCR法（real-time FQ-PCR）分别测定Ghrelin mRNA和GHSR mRNA;免疫组织化学法测定Ghrelin蛋白和GHSR蛋白。结果：0日龄限食SGA组仔鼠胃底组织中Gherlin mRNA和蛋白表达均高于限食AGA组和对照组,下丘脑GHSR mRNA的表达低于限食AGA组和对照组;20日龄SGA组追赶生长仔鼠胃底Ghrelin蛋白、下丘脑GHSR mRNA和蛋白的表达高于SGA未追赶生长和对照组仔鼠;40日龄时3组间则差异无统计学意义（P>0.05）。结论：Ghrelin-GHSR可能参与了宫内IUGR胎鼠的生理调节或病理过程,且可能在出生后参与了SGA个体早期追赶生长的调控。     

Aortic intima–media thickness in nicotine-exposed rat pups during gestation and lactation period

There have been several studies confirming an association between maternal smoking during pregnancy and low birth weight. The detrimental effect of nicotine exposure beginning in fetal life continues during lactation, in infancy and in the early childhood period. In our previous studies, we found increased aortic intima–media thickness (aIMT) as a preatherosclerotic lesion in neonates with intrauterine growth restriction and in infants of smoking mothers. We aimed to evaluate histopathologically the effect of nicotine exposure during pregnancy and lactation period on fetal growth and aIMT at postnatal 45 days of age (end of the mid-adolescent period) in rat pups living in the same conditions. Gravid rats were assigned into three groups. In nicotine A, pregnant rats received 6 mg/kg/day nicotine intraperitoneally during pregnancy from 1 to 21 days of gestation and lactation (until postnatal day 21). Nicotine B received 3 mg/kg/day nicotine for the same period. Control pregnant rats received only saline intraperitoneally. Abdominal aIMT was studied histopathologically at postnatal 45 days of age. Nicotine exposure resulted in decreased birth weight and pregnancy weight gain. The mean aIMT values of the rat pups exposed to nicotine in both nicotine A and B groups were higher than those of the control group (103.78 ± 21.33 μm, 99.11 ± 30.12 μm, and 62.56 ± 7.18 μm, respectively). In conclusion, the detrimental effect on birth weight of nicotine exposure that began in fetal life is dose dependent. Nicotine exposure during intrauterine life and the lactation period causes increased aIMT in rat pups.     

Fatty acid composition of the brain of intrauterine growth retardation rats and the effect of maternal docosahexaenoic acid enriched diet

Aim

To determine whether the intrauterine environment affects lipid metabolism, we measured the fatty acid composition of the brain in rats with intrauterine growth retardation (IUGR) induced by synthetic thromboxane A2 (STA2). Additionally, we evaluated the effect of maternal docosahexaenoic acid (DHA)-enriched diet.

Methods

Two experimental diets were provided: soy bean oil and DHA-enriched diets. Maternal rats were divided randomly into three groups, STA2−/Soy (Sham), STA2+/Soy (IUGR), and STA2+/DHA (DHA) groups. The Sham and IUGR groups were fed the soy diet, and the DHA group received the DHA-enriched diet from embryonic day 7 until delivery. On postnatal days 1 and 7, the pups were weighed and their brains were removed for lipid analysis.

Results

The body weight of the IUGR and DHA groups was significantly less than that of the Sham group both on the postnatal days 1 and 7, whereas it was not significantly different between the IUGR and DHA groups either on postnatal day 1 or day 7. There was no significant difference in the percentage of DHA between the Sham and IUGR groups either on postnatal day 1 or 7. On the other hand, the percentage of DHA was higher in the DHA group than in the IUGR group both on the postnatal days 1 and 7.

Conclusions

The fatty acid composition in the brain was not altered in the STA2-induced IUGR rat model. Increased DHA percentage was observed in the maternal DHA-enriched diet group, although no beneficial effect on body weight gain was observed.     

胰岛素受体底物在宫内发育迟缓大鼠胰腺组织中的表达

目的：研究胰岛素受体底物1（IRS-1）和胰岛素受体底物2(IRS-2)在宫内发育迟缓（IUGR）大鼠生后0周、3周和8周胰腺组织中的表达,探讨IUGR个体易患代谢综合征的分子机制。方法：采用母孕期低蛋白饮食法建立IUGR大鼠模型,应用RT-PCR技术检测子鼠在生后0周、3周、8周胰腺组织中IRS-1和IRS-2 mRNA水平。采用Western 杂交检测 IRS-1和IRS-2蛋白的表达。母孕期得到正常饮食的子鼠作为对照组。结果：IUGR 组0周、3周、8周胰腺组织IRS-2 mRNA和蛋白表达水平均显著低于对照组(P<0.05）,IRS-1 mRNA 和蛋白表达水平与对照组相比差异无统计学意义（P＞0.05）。结论：IUGR子鼠生后0周、3周和8周胰腺组织中IRS-2 mRNA和蛋白水平显著下降,可能是 IUGR 个体易患代谢综合征的分子机制之一。［中国当代儿科杂志,2010,12(12)：972-975］     

早期丰富环境对大鼠远期行为发育及血清皮质酮的影响

目的：探讨早期丰富环境对大鼠行为发育及血清皮质酮的影响。方法：将45只新生大鼠随机分为丰富环境组、空白对照组和隔离环境组,于大鼠生后31 d分别采用开场实验、Lat迷宫测验评价大鼠焦虑、烦躁等行为;采用放射免疫学方法测定大鼠血清皮质酮水平。结果：丰富环境组血清皮质酮水平（8±3 ng/mL）较空白对照组（11±4 ng/mL）及隔离环境组（22±4 ng/mL）明显降低,差异有统计学意义（P<0.01）。开场实验结果显示,丰富环境组大鼠穿越格子数、直立次数、理毛次数明显少于空白对照组及隔离环境组大鼠（P<0.05）。Lat迷宫试验结果显示,丰富环境组大鼠穿越角落数、直立次数、斜搭在墙上的频率明显少于空白对照组与隔离环境组大鼠（P<0.05）。结论：早期丰富环境使大鼠能保持较低的皮质酮水平,减缓焦虑、烦躁等行为,对促进脑发育有重要意义。     

早期营养干预对宫内生长迟缓大鼠小肠发育及体格生长的影响(英文)

目的：了解出生后早期营养干预对宫内生长迟缓 (IUGR)大鼠体格、小肠发育的影响。方法：生后 4周内每周分别测量正常大鼠正常饮食组 (CC) ,IUGR正常饮食组 (IC)、低蛋白饮食组 (IL)及高蛋白饮食组(IH)大鼠体重、身长。并于出生时及第 3,4周测量其小肠长度、重量及肠粘膜双糖酶 (乳糖酶、麦芽糖酶、蔗糖酶 )活力。结果：①IUGR鼠出生时体重、身长、小肠长度及重量均显著小于正常鼠 (P <0 .0 5 ) ;乳糖酶、麦芽糖酶活力高于正常组 (P <0 .0 5 )。②IL组身长、体重、小肠重量及长度生后初 4周均落后于CC ,IC和IH组 (P <0 .0 5 ) ;IH组体格、小肠追赶生长迅速 ,4周时体重与CC组比较差异无显著性 (P >0 .0 5 )。③ 3周时IL ,IH组乳糖酶活力高于CC组 (P <0 .0 5 ) ;4周时IL组蔗糖酶活力小于CC组 (P <0 .0 5 )。结论：生后早期营养干预对IU GR大鼠早期体格追赶生长、小肠发育有重要的影响。     

A Developmental Study of Reflex and Activity in Rats with Microcephaly Induced by Prenatal Methylazoxymethanol Acetate (MAM) Treatment

Pregnant Wistar rats were given a single i. p. injection of 30 mg/kg methylazoxymethanol (MAM) acetate or saline on day 13 of pregnancy (vaginal plug = day 0). All offspring were subjected to reflex tests during the preweaning period (surface righting reflex, from 3 to 12 days of age; negative geotaxis reflex, from 5 to 12 days of age), and then selected male rats were subjected to open-field test during the postweaning period (from 21 to 35 days of age). The MAM-treated rats showed significantly longer latencies in the both reflex tests, and also significant hyperactivity in the open-field test. These behavioral alterations were analyzed in relation to the large size reduction in the cerebral cortex and the morphological abnormalities of the hippocampus in the MAM-treated rats.     

Fructose-1,6-diphosphatase and glucose-6-phosphatase in newborn rats with intrauterine growth retardation.

The activities of two gluconeogenic enzymes, glucose-6-phosphatase and fructose-1,6-diphosphatase were examined in the normal and intrauterine growth retarded (IUGR) rat during the first 5 days of life. The fructose-1,6-diphosphatase activity, 1.54 +/- 0.10 mumol/min/g liver (means +/- SEM) in control and 1.47 +/- 0.20 in the IUGR rats, increased in both groups on days 2--4 but remained significantly lower in the IUGR rats through day 4 (4.53 +/- 0.6 mumol/min/g liver in control and 3.09 +/- 0.22 mumul/min/g liver in the IUGR rats, P less than 0.01). The glucose-6-phosphatase activity increased similarly in both groups. The weight of the IUGR rats remained lower through the third postnatal day (6.47 +/- 0.42 compared to 8.64 +/- 0.27 g in control rats). Blood glucose concentrations at birth were 117 +/- 11 mg/dl in control rats and 73 +/- 11 mg/dl in the IUGR rats (P less than 0.01). Although the glucose concentrations increased in both groups on days 2--4, the IUGR rats maintained relatively lower levels (P less than 0.01). The results indicate that IUGR fetal rats do not have augmented gluconeogenesis in spite of hypoglycemia. In addition, effective gluconeogenesis in the neonatal period appears to be delayed.     

Effect of respiratory acidosis on glucose homeostasis in experimental intrauterine growth retardation in rats

Hypoglycemia and asphyxia account for a significant proportion of morbidity in the infant with intrauterine growth retardation (IUGR). The purpose of this study was to evaluate changes in glucose homeostasis in IUGR rats during acute respiratory acidosis. IUGR was produced by bilateral uterine artery ligation at 17 days of gestation in 14 pregnant rats with 23 successfully delivered pups. The normal pups (n = 31) were those whose mothers were sham operated at the same gestational period. The IUGR and normal pups were studied at 2 days of age. One group of pups was studied under room air while another was subjected to 20 min of exposure to a gas mixture of 10% O2/15% CO2, balanced with N2. Gluconeogenesis in the liver and carcass, as well as plasma glucose and catecholamines were determined before and after the exposure to the gas mixture. The results showed that the 2-day-old IUGR rats have lower body weight (P less than 0.001), liver weight (P less than 0.001), plasma glucose (P less than 0.001), and rate of gluconeogenesis (P less than 0.01) when compared with the normally grown rats. During respiratory acidosis, the normally grown rats showed an increase in plasma epinephrine (P less than 0.005) without significant change in plasma glucose and rate of gluconeogenesis. The IUGR rats on the other hand, demonstrated a decrease in rate of gluconeogenesis (P less than 0.02), an increase in plasma glucose (P less than 0.001) while the plasma epinephrine level remained unchanged. We speculate that respiratory acidosis blunted cellular metabolism in the IUGR rat resulting in decreased peripheral glucose utilization.(ABSTRACT TRUNCATED AT 250 WORDS)     

胰岛素受体底物在宫内发育迟缓大鼠肝脏组织中的表达

目的 研究胰岛素受体底物1( IRS-1)和胰岛素受体底物2(IRS-2)在宫内发育迟缓(IUGR)大鼠出生0周、3周和8周时肝脏组织中的表达,探讨IUGR个体易患代谢综合征(MS)的分子机制.方法 采用母孕期低蛋白饮食法建立IUGR大鼠模型,应用反转录( RT)-PCR技术检测仔鼠在出生0周、3周、8周肝脏组织中IRS-1、IRS-2 mRNA水平,凝胶电泳条带用成像系统照相定量分析结果,分别计算PCR产物条带与β-actin条带吸光度值的比值,作为目的基因相对表达量.采用Western blot杂交检测仔鼠在出生0周、3周、8周肝脏组织IRS-1蛋白、IRS-2蛋白的水平表达.母孕期得到正常饮食的仔鼠作为对照组.结果 IUGR鼠出生时体质量显著低于对照组,出生后出现生长追赶,至8周时IUGR组体质量超过对照组;IUGR组0周、3周、8周时其肝脏组织IRS-2 mRNA和蛋白表达水平均显著低于对照组(Pa＜0.05,0.01),肝脏组织IRS-1 mRNA和蛋白表达水平与对照组比较差异无统计学意义(Pa＞0.05).结论 IUGR大鼠0周、3周和8周肝脏组织中IRS-2 mRNA和蛋白水平显著下降,可能是IUGR个体易患MS的分子机制之一.     

Lipin基因表达与宫内发育迟缓大鼠肝脏脂肪含量的相关性研究

目的 探讨宫内发育迟缓（intrauterine growth retardation,IUGR）大鼠肝脏Lipin2基因和内脏脂肪组织Lipin1基因的表达与肝脏脂肪含量的相关性。 方法 使用母孕期低蛋白（10%蛋白）饮食法喂养孕鼠制造IUGR仔鼠模型,对照组孕鼠在孕期使用正常蛋白饲料喂养（蛋白含量21%）。分别在两组仔鼠生后1 d、1周、3周、8周和12周时称体重并留取仔鼠的肝脏组织,在生后3周、8周和12周留取两组仔鼠的内脏脂肪组织。采用3.0T氢质子磁共振波谱法检测两组大鼠生后3周、8周、12周时肝脏脂肪含量;采用Real-time PCR法检测两组大鼠各时间点肝脏组织Lipin2、内脏脂肪组织Lipin1基因的mRNA表达水平;采用Western blot法检测两组大鼠肝脏组织Lipin2、内脏脂肪组织Lipin1蛋白表达水平。采用Pearson相关分析Lipin mRNA及其蛋白表达与肝脏脂肪含量的相关性。 结果 生后3周、8周、12周时,IUGR组仔鼠内脏脂肪组织Lipin1 mRNA及其蛋白表达水平均高于对照组（P<0.05）。生后1 d时IUGR组肝脏组织Lipin2 mRNA及其蛋白表达水平低于对照组（P<0.05）,而生后1周、3周、8周、12周时Lipin2 mRNA及其蛋白表达水平均高于对照组（P<0.05）。生后3周时IUGR仔鼠和对照组肝脏脂肪含量比较差异无统计意义（P>0.05）,生后8周、12周时IUGR组仔鼠肝脏脂肪含量显著高于对照组（P<0.05）。Lipin1蛋白和mRNA表达与肝脏脂肪含量呈正相关（分别r=0.628、0.521,P<0.05）,Lipin2蛋白和mRNA表达与脂肪含量呈正相关（分别r=0.601、0.524,P<0.05）。 结论 IUGR大鼠内脏脂肪组织Lipin1和肝脏组织Lipin2 mRNA及其蛋白表达上调可引起肝脏脂肪含量增加,可能与导致IUGR大鼠成年期肥胖有关。     

TGF-β1、TGF-βr Ⅲ在邻苯二甲酸二丁酯诱导尿道下裂新生雄性仔鼠生殖结节中的表达及意义

目的 通过验证大鼠孕期污染邻苯二甲酸二丁酯(DBP)所致尿道下裂雄性仔鼠生殖结节中TGF-β1、TGF-βr Ⅲ的表达异常,探讨其在DBP生殖毒性过程中的作用机制.方法 孕鼠20只,随机分二组,在怀孕(GD)14～18 d期间,每天分别灌胃给予大豆油、DBP750 mg/kg,出生第一天(PND1),统计仔鼠出生数,尿道下裂发生率.PND7,雄性仔鼠称重,测量雄性仔鼠肛门至生殖器距离(AGD),拍摄尿道下裂大体图片,取尿道下裂生殖结节进行病理学切片检查,用实时定量逆转录聚合酶链反应(Real-time quantitative PCR)方法 检测生殖结节中的TGF-β1、TGF-βr Ⅲ的mRNA表达水平.结果DBP染毒后导致新生仔鼠与正常组相比数量明显减少,雄性仔鼠尿道下裂的发生率为:43.75%.PND7时,雄性仔鼠体重明显下降,AGD明显缩短.大体图片和病理切片显示典型尿道下裂改变.同时与对照组相比,DBP导致尿道下裂雄性仔鼠生殖结节中TGF-β1、TGF-βr Ⅲ的tuRNA表达水平明显下降.结论 DBP对母体有着明显的毒性作用,DBP干预了TGF-β1、TGF-βr Ⅲ基因的表达,导致子代的生殖结节发育异常,引起尿道下裂.     

钳夹子宫血管致宫内生长迟缓幼鼠肝及脑组织变化的研究

目的　建立简便可靠的大鼠宫内发育迟缓(IUGR)模型,观察其幼鼠肝及脑重量和病理变化。方法　将大鼠分为2组:钳夹组于孕17d 行双侧子宫血管钳夹术30m in;对照组行同期开关腹术,但不钳夹子宫血管。随机获得孕21d 剖宫产及自然分娩两队。结果　剖宫产队:钳夹组幼鼠体重、肝重、脑重均明显低于对照组(P< 0.05),肝及脑组织光镜下有明显的病理形态学异常。自然分娩队:生后d6 两组幼鼠体重无明显差异(P> 0.05),但钳夹组幼鼠肝及脑重仍明显低于对照组(P<0.05),光镜下脑的异常改变部分恢复,肝的形态学改变恢复正常。结论　钳夹子宫血管法能造成IUGR模型,且IUGR幼鼠出现可测定的肝及脑损伤,生后6d 肝损伤恢复,脑损伤部分恢复