Effects of supplement of thyroxine for hypothyroid pregnant rat on the expression of homeobox gene Nkx2.1 mRNA in the offspring's cerebrum tissue / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the effects of thyroid hormone on the expression of homeobox gene Nkx2.1 mRNA in child rat by supplying their hypothyroidism pregnant mother with different dose of levothyroxine (L-thyroxine, L-T(4)) in different times.</p><p><b>METHODS</b>120 female Wistar rats were randomly divided into eight groups according to the body weight: control group, non-treatment hypothyroidism group, hypothyroidism groups supplied with L-T(4) in high, medium and low dosage in early stage (1st-17th day of pregnancy) and in late stage (18th day of pregnancy-20th day after childbirth). According to 100 grams of body weight, the concentrations of L-T(4) were 3.5, 2.0, 0.5 µg/d in high, medium and low dosage group. All the rats were fed with low-iodine food. The control group was given 200 µg/L potassium iodate solution as drinking water and the other groups were given deionized water. After three months, the rats were mated with normal male rats. After the pregnancy was confirmed, hypothyroidism groups were supplied with L-T(4) of different concentrations. Brain samples were taken from the 17-day fetal rats, new-born and 20-day old offsprings and the levels of Nkx2.1 mRNA in brain tissue were analyzed by real-time fluorescence quantitative PCR techniques.</p><p><b>RESULTS</b>The levels of TT(3) in hypothyroidism groups supplied with L-T(4) in high, medium and low dosages in early and late pregnant stages, non-treatment hypothyroidism group and control group were (0.85 ± 0.17), (0.81 ± 0.18), (0.86 ± 0.21), (0.85 ± 0.20), (0.89 ± 0.18), (0.85 ± 0.20), (0.86 ± 0.20), (1.08 ± 0.07) nmol/L (F = 4.08, P < 0.01); the levels of TT(4) in each group were (0.43 ± 0.16), (0.39 ± 0.11), (0.39 ± 0.13), (0.43 ± 0.17), (0.51 ± 0.19), (0.43 ± 0.16), (0.41 ± 0.15), (39.43 ± 14.16) nmol/L (F = 31.99, P < 0.01); the levels of FT(3) in each group were (3.29 ± 0.61), (3.29 ± 0.61), (3.24 ± 0.61), (3.28 ± 0.63), (3.31 ± 0.59), (3.28 ± 0.50), (3.24 ± 0.49), (4.93 ± 0.46) pmol/L (F = 5.79, P < 0.01); the levels of FT(4) in each group were (3.38 ± 0.80), (3.31 ± 0.67), (3.29 ± 0.73), (3.27 ± 0.71), (3.48 ± 0.81), (3.56 ± 0.66), (3.29 ± 0.61), (27.29 ± 4.53) pmol/L (F = 26.34, P < 0.01). The expression of Nkx2.1 mRNA in non-treatment hypothyroidism group (9.15 × 10(-5) ± 9.17 × 10(-5)) was lower than control group (65.1 × 10(-5) ± 40.90 × 10(-5)) in 17th day of pregnancy (t = 66.224, P < 0.05); the expression of Nkx2.1 mRNA in non-treatment hypothyroidism group (3.16 × 10(-5) ± 0.142 × 10(-5)) was lower than control group (55.6 × 10(-5) ± 51.05 × 10(-5)) in new-born (t = 102.225, P < 0.05); the expression of Nkx2.1 mRNA in non-treatment hypothyroidism group (8.09 × 10(-5) ± 8.21 × 10(-5)) was lower than control group (13.9 × 10(-5) ± 7.43 × 10(-5)) in 20th day after birth (t = 9.235, P < 0.05). The trend of Nkx2.1 mRNA in hypothyroidism groups was decreased in group supplied with L-T(4) in medium dosage in early stage descends in 17th day of pregnancy, new-born and 20th day after birth (57.1 × 10(-5) ± 22.90 × 10(-5)), (30.8 × 10(-5) ± 27.20 × 10(-5)), (17.1 × 10(-5) ± 0.623 × 10(-5)) (F = 13.394, P < 0.01). The expression of Nkx2.1 mRNA in hypothyroidism groups supplied with L-T(4) in medium dosage in early stage in 17th day of pregnancy, new-born and 20th day after childbirth was closest to the control group in every period (t values were 0.225, 0.336, 0.345, all P values > 0.05).</p><p><b>CONCLUSION</b>The difference in the expression of homeobox gene Nkx2.1 mRNA is highly related to the level of thyroid hormone.</p>

Effects of thyroid hormone on the expression of homeobox gene Nkx6.1 in the cerebrum tissue of offspring of hypothyroidism rat / 中国地方病学杂志

Objective To explore the effects of thyroid hormone on the expression of homeobox gene Nkx6.1 in offspring of hypothyroidism rats and the relationship between gene expression and hormone level by supplying their hypothyroidism pregnant mother with thyroid hormone. Method A total of 240 Wistar rats were half nude and half female. Female rats were randomly divided into eight groups: control, hypothyroidism group, hypothyroidism groups which were supplied with thyroid hormone in high, medium and low dosage in early stage(1- 17 d) and in late stage( 18 - 20 d). According to 100 grams of body weight, the concentration of thyroid hormone were 3.5,2.0,0.5 μg/d in high, medium and low dosage group. All the rats were fed with low-iodine food. The normal control group was given KIO_3 solution and the other groups were given deionized water. After three months female rats were mated with male rats. The content of Nkx6.1 mRNA in brain tissue of 17-day fetal rats, new-born and 20- day old offspring by real-time fluorescence quantitative PCR techniques. Results①A rat model of hypothyroidism was successfully established, there were statistical significance between 8 groups in TT_3,TT_4,FT_3,FT_4(F=4.08,31.99,5.79,26.34, all P < 0.01 ). ② The expression of Nkx6.1 mRNA had significant difference(F = 758.720, 1121.589,144.716, all P < 0.01 ) between groups in 17-day fetal rats, new-bern and 20-day old offsprings and intra- groups in different time (F=2898.863,325.605,716.285,56.329,236.727,196.678,7115.752,9152.306, all P < 0.01 ). ③The time factor and dosage factor had influence on Nkx6.1 mRNA expression(F = 1176.655,246.530, all P < 0.01 ). There were interaction between time and dosage factor(F = 1249.934, P < 0.01 ). ④Comparison of Nkx6.1 mRNA expression between hypothyroidism group and normal control group had significant difference in the above three time points(all P < 0.01 ). ⑤Comparisons of Nkx6.1 mRNA expression between 6 hypothyroidism groups which were supplied with thyroid hormone and hypothyroidism group had significant difference(all P < 0.01 ) in new-bern and 20-day old offspring; comparisons of Nkx6.1 mRNA expression between hypothyroidism groups which were supplied with high and medium thyroid hormone and hypothyroidism group had significant difference in 17-day fetal rats(all P < 0.01 ). ⑥Comparison of Nkx6.1 mRNA expression between hypothyroidism groups which were supplied with medium thyroid hormone in early stage and normal control group had no statistical significance (all P > 0.05), while between the other 5 groups which were supplied with thyroid hormone and normal control group had significant difference(all P < 0.01 ) in the above three time points.⑦Multiple comparison of early stage groups which were supplied with thyroid hormone showed that the expression of Nkx6.1 mRNA had significant difference(all P < 0.01) between high, low dosage groups and medium group in 17-day fetal rats, new-bern and 20-day offspring(all P< 0.01). ⑧Multiple comparison of late stage groups supplied with thyroid hormone showed that old offspring and between high dosage groups and low dosage groups in 17-day fetal rats and 20-day the expression of Nkx6.1 mRNA had significant difference(all P < 0.01 ) between three groups in new-bern and 20- day old offspring. Conclusion The expression of Nkx6.1 in rats offspring is highly related to the supply dosage and supply time of thyroid hormone in hypothyroidism pregnant rats.

Sleep-related hypoxemia aggravates systematic inflammation in emphysematous rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Sleep disturbance is common in patients with emphysema. This study aimed to develop a novel model of sleep-related hypoxemia (SRH) in emphysema (SRHIE) with rats, and to explore the inflammatory status of SRHIE in lung, liver, pancreas, carotid artery and whole blood.</p><p><b>METHODS</b>Seventy-five male Wistar rats were assigned to 5 groups with 15 per group according to the exposure conditions. The protocols varied with the degree of hypoxia exposure and severity of pre-existing emphysema caused by cigarette smoke exposure: (1) SRH control (SRHCtrl) group, sham smoke exposure (smoke exposure, exposed to smoke of 15 cigarettes twice everyday, 16 weeks) and SRH exposure (12.5% O2, 3 hours, SRH exposure, divide total hypoxia time (1.5 hours or 3 hours) into 4 periods evenly (22.5 minutes or 45 minutes) and distribute these hypoxia periods evenly into physiological sleep time of rats identified by electroencephalogram, week 9 to week 16); (2) Emphysema control (ECtrl) group, smoke exposure and sham SRH exposure (21% O2, 3 hours); (3) Short SRH in emphysema (SRHShort) group, smoke exposure and short SRH exposure (12.5% O2, 1.5 hours); (4) Mild SRH in emphysema (SRHMild) group, smoke exposure and mild SRH exposure (15% O2, 3 hours); (5) Standard SRH in emphysema (SRHStand) group, smoke exposure and SRH exposure (12.5% O2, 3 hours). ECtrl, SRHShort, SRHMild and SRHStand groups were groups with emphysematous rats. Two days before the end of exposure, 5 rats in each group were randomly selected for arterial blood gas analysis. In the rest 10 rats in each group, we obtained blood samples and bronchoalveolar lavage fluid (BALF) for routine tests. We also obtained tissue blocks of lung, liver, pancreas, and right carotid artery for pathologic scoring and measurements of liver oxidative stress (measuring hepatic oxidative stress enzymes, superoxide dismutase (SOD) activity, catalase (CAT) activity and malondialdehyde (MDA) concentration).</p><p><b>RESULTS</b>Emphysematous groups had higher mean linear intercept (MLI) and mean alveolar number (MAN) values than SRHCtrl group. MLI values in SRHStand group were the highest (all P < 0.05). O2Sat in SRHStand rats when SRH exposure was (83.45 ± 1.76)%. Histological scores of lung, liver, pancreas and right carotid artery were higher in emphysematous groups than SRHCtrl group, and SRHStand group were the highest (all P < 0.05) (SOD and CAT values were lower and MDA values were higher in groups with emphysema than without and in SRHStand group than in ECtrl group (all P < 0.05)). MDA values were the highest in SRHStand group (all P < 0.05). Total cellular score in BALF and White blood cell (WBC) in whole blood were the highest in SRHStand group (all P < 0.05). Lymphocyte ratios were the highest in SRHStand group both in BALF and blood (all P < 0.05). Red blood cell (RBC) and hemoglobin in emphysematous groups were higher than that in SRHCtrl group, and SRHStand group were higher than ECtrl group (all P < 0.05).</p><p><b>CONCLUSIONS</b>With a proper novo model of SRHIE with Wistar rats, we have demonstrated SRH may aggravate the degree of emphysematous changes, polycythemia, oxidative stress and systematic inflammation. SRH and emphysema may have a synergistic action in causing systematic damages, and lymphocyte may be playing a central role in this process. Longer duration and more severe extent of SRHIE exposure also seem to result in more serious systematic damages. The mechanisms of all these concerned processes remain to be studied.</p>

Expression of neuron specific enolase gene in the brains of rats induced by iodine excess / 中国地方病学杂志

Objective To observe expression of neuron specific enolase (NSE) gene in the brain of rats induced by iodine excess. Methods One hundred and fifty one-month weaning Wistar rats were divided into ten groups according to 5 × 2 factorial experiment. Rats were fed with normal feedstuff and water of a series of iodine concentration by adding potassium iodide respectively: norrmal iodine (NI), five-fold high iodine (5HI), ten-fold high iodine(10HI), fifty-fold high iodine(50HI) and one hundred-fold iodine(100HI). After these rats were fed for three or six months, rat serum thyroid hormones were measured by radioimmunoassay including TT4, TT3, FT4, FT3, rT3 and the mRNA level of NSE in rat brain tissue was studied using RT-PCR technique. Results The levels of serum TT4 and TT3 were significantly different in five iodine level groups(F values were 18.867,27.287, both P < 0.01). The interaction between time and iodine level in TT4 was significant in our study(F values were 2.486, P < 0.05). The levels of TT4 and TT3 of 100 HI group at third and sixth month were lower than those of NI, 5HI, 10HI, 50HI groups in the same period (all P < 0.01). The levels of serum FT4, FT3 and rT3 were significantly different at different time(F values were 4.968,27.046,59.776 respectively, P < 0.05 or < 0.01) and in different iodine level groups(F values were 33.058,28.420,17.482 respectively, all P < 0.01). Moreover, the interaction between time and iodine level in FT3 and rT3 was significant in our study(F values were 6.894,5.233 respectively, both P < 0.01). FT4, FT3 and rT3 in 100HI group were lower than that of other iodine dosage groups at the same time (P < 0.05 or < 0.01). The levels of NSE mRNA in brain tissue was significantly different in five iodine level groups (F values were 29.006, P < 0.05). The levels of mRNA NSE of 100HI group in both three and six months (0.61 ± 0.19,0.61 ± 0.22) were all lower than that of any other groups[NI(0.73±0.13 and 0.72 ±0.26), 5HI (0.72 ± 0.15 and 0.72±0.16), 10HI (0.73 ±0.32 and 0.70±0.13), 50HI(0.71±0.18 and 0.69±0.31), all P < 0.05]. The results of correlation analyses show that the levels of serum FT3 and FT4 had correlations with the levels of NSE mRNA (P < 0.05) both in three and six months(r values were 0.987, 0.969 in three month, and 0.890, 0.910 in six month respectively). Conclusions The expression of NSE gene can tolerant the excess of iodine to a certain extent. Exposure to heavy excess iodine(100HI) can decrease the mRNA level of NSE gene. FT4 and FT3 may both have important roles on the regulation of NSE mRNA induced by excess iodine.

Overdose of iodine on expression of CCK gene in rat brains / 中华预防医学杂志

<p><b>OBJECTIVE</b>To observe the effect of overdose iodine on the expression of CCK gene in brains of rats and identify the possible mechanisms.</p><p><b>METHODS</b>One-month weaning Wistar rats were randomly divided into five groups which were fed with normal feedstuff and water supplemented with different concentrations of potassium iodide, named A group (iodine ration was about 6.15 microg per day), B group (iodine ration was about 30.75 microg per day), C group (iodine ration was about 61.5 microg per day), D group (iodine ration was about 307.5 microg per day) and E group (iodine ration was about 615 microg per day). Rats were sacrificed after being fed for three or six months. Then serum thyroid hormones were measured by radioimmunoassay and the mRNA level of CCK gene was studied by using RT-PCR technique.</p><p><b>RESULTS</b>At the end of three months, the values of thyroid hormones in E group [TT4 (45.2 +/- 13.7) nmol/L, TI'3 (0.65 +/- 0.20) nmol/L, FT3 (0.93 +/- 0.45) pmol/L, FT4 (7.07 +/- 2.43) pmol/L, rT3 (0.15 +/- 0.04) nmol/L] were all lower than those in A group [TT4 (76.0 +/- 18.8) nmol/L, TT3 (1.34 +/- 0.41) nmol/L, FT3 (2.45 +/- 0.62) pmol/L, FT4 (15.12 +/- 3.40) pmol/L, rT3 (0.24 +/- 0.04) nmol/L]. There were significant differences between E group and A group on the levels of serum TH (F values are 14.68, 16.03, 21.16, 20.25, 13.52 respectively, P < 0.01); FT3 levels in C and D groups were significantly decreased as compared to A and B groups (F = 21.16, P < 0.05). rT3 level in D group was significantly decreased compared with A,B and C groups (F = 13.52, P < 0.05). At the end of six months, the levels of serum TH in E group (TT4 (51.84 +/- 15.83) nmol/L, TT3 (0.77 +/- 0.22) nmol/L, FT4 (6.88 +/- 2.23) pmol/L, FT3 (0.74 +/- 0.28) pmol/L, rT3 (0.14 +/- 0.03) nmol/L) were lower than those in any other groups (F values were 6.05, 12.22, 11.25, 13.42, 5.89 respectively, P < 0.05). At the end of both three and six months, the mRNA levels of CCK gene in E group were lower than any other groups (F values were 4.04, 3.95 respectively, P < 0.01). The results of correlation analysis showed that serum FT4 had linear correlation with levels of CCK mRNA (r values were 0.990, 0.948 respectively; P < 0.05); However serum FT3 had no linear correlation with the levels of CCK mRNA (r values are 0.970, 0.932 respectively).</p><p><b>CONCLUSIONS</b>Exposure to overdose of iodine (iodine ration was 100-fold higher than that of A group) could decrease the mRNA level of CCK gene. Compared with FT3, FT4 might have more important role on the regulation of CCK mRNA induced by excess of iodine.</p>

Effect of rhBMP-2 on the Osteogenesis of Osteoblast Compounded Chitosan / 中国生物工程杂志

Recombinant human BMP-2 was compounded with chitosan/gelatin/hydroxyapatite(HCG) scaffold and the complex was sterilized by 60Co radiating. Osteoblast isolated from cranial bones of newborn rat was primary cultured and seeded onto the complexes. 3 days after culturing, scanning electron microscope(SEM) was applied to detect the compatibility of the cell with the complex. SEM showed osteoblast attached closely with the complex and grew well in its pores. Then the complexes with osteoblast modification were implanted into athymic nude mice subcutaneously. 8 weeks after implantation, X-ray photograph and histological observation were applied to detect the bone formation of the complexes. Under X-ray a high-density areas consistent with the shape of the implanted complex could be seen. Histological observation also proved there was bone formation in the interspace of the complex. A conclusion was drawn that rhBMP-2 compounded HCG scaffold had good osteogenesis ability in vivo.

Effects of different levels of iodine nutrition on liver typeⅠdeiodinase and brain typeⅡdeiodinase activities in rat / 中华内分泌代谢杂志

Wistar rats with different levels of iodine nutrition were killed after 3,6 and 12 months of experiments.Serum thyroid hormones were assayed with RIA.The activity of typeⅠdeiodinase(DⅠ)and typeⅡdeiodinase(DⅡ)was measured based on the release of radioiodide from the ~(125)Ⅰ-labeled substrate.The result showed that hypothyroidism reflected by decreased T_4 happened during the initial phase of iodine deficiency.The activity of DⅠand DⅡin rats was raised significantly in iodine deficiency groups.An excess of iodine inhibited DⅠactivity resulting in decreased serum TT_3 and FT_3.However,DⅡactivity increased in rats with iodine excess, attributing to the inactivation of T_3 and T_4 to the substrate of DⅡenzyme.