| Background and purposeNeonatal intracranial hemorrhage is a serious brain injury occurring in the neonatal period, especially for the premature infants. It is one of the most common causes of morbidity and mortality, and the survivors often left with serious neurological deficiency, including mental retardation, sensory or motor dysfunction, ataxia, and even cerebral palsy. In the recent years, with the development of technology in perinatal medicine and the establishing of neonatal intensive care unit (NICU), the survival incidence of periventricular-intraventricular hemorrhage has significantly improved.The preterm brain injury is divided into periventricular-intraventricular hemorrhage (PVH-IVH) and periventricular leucomalacia (PVL). The neonate brain injury caused by intracranial hemorrhage by now can not be cure yet,but clinical investigation in recent two years show that most newborn infants especially preterm infants confront with hypothyroid. At the same time medical research find that thyroid hormone exerts dynamic effects on the vascular during CNS development by altering the expression of angiogenic factors such as vascular endothelial growth factor A (VEGF A) and basic fibroblast growth factor (FGF2). In this study thyroid hormone (TH) and proplthiouracil(PTU) was added to the drinking water of the adult female rats from the first day of pregnancy separately to the first day of lactation period, newborns of post neonatal day 1st in each group were used:their serum total thyroxine (TT4), total triiodothyronine (TT3) were estimated by electrochemical luminescence and brain vascular endothelial growth factor(VEGF) were measured by enzyme-linked immunosorbent serologic assay (ELISA) at the same time, furthermore, immunohistochemistry was used to exhibit the expression of VEGF in the germinal matrix region in their brain.The present study aimed to assess the effect of hypothyroidism and hyperthyroidism in brain angiogenesis of rat newborns,at the same time to offer some medical data in preventing of intracranial hemorrhage of the newborns and point out an new way in preventing of intracranial hemorrhage of the newborns.Materials and methods1 Animal model7 nests of clean SD rats were used in this experiment,3 rats for each,18 mature virgine females and 3 mature males. Females of each nest were divided into 3 groups randomly after mating:6-N-propyl-2-thiouracil(PTU) regulated group,thyroid hormone(TH) regulated group and Control group from the first day of pregnancy to the first day of lactation period.1) 6-N-propyl-2-thiouracil(PTU) regulated group:six rats were rendered hypothyroid, to establish a hypothyroid rat model PTU was administered to the drinking water (0.1g/L). drinking bottles were replaced daily with fresh PTU solution. PTU was offered directly after mating.2) thyroid hormone(TH) regulated group: further six rats were rendered Hyperthyroid by exogenous thyroxine (T4) intragastric administration in the dose of 200ug/kg body weight,these T4 was administered to the drinking water (0.02 g/L), drinking bottles were replaced daily with fresh T4 solution, T4 was offered directly after mating.3)control group:six rats received tap water.2 Estimation of serum TT4 and TT3 levelsNewborn rats were deeply anesthetized with 0.02ml sodium Phenobarbital and subsequently killed by decapitation. Their plasma were collected and centrifuged at 1000×g for 20 minutes to separate the serum, which was collected and stored in fridge at the temperature of -20℃, plasma TT4 and TT3 concentrations were determined using electrochemical luminescence.3 Estimation of brain vascular endothelial growth factor (VEGF) levelsNewborn rats were deeply anesthetized with 0.02ml sodium Phenobarbital and subsequently killed by decapitation, the brains were rapidly removed and stored at-70℃for ELISA.4 ImmunohistochemistryNewborn rats were deeply anesthetized with 0.02ml sodium Phenobarbital and transcardically perfused with 0.9%NaCl, followed by 4% paraformaldehyde per 0.1mmol/L phosphate-buffered saline, PH7.4, the brains were removed rapidly,postfixed for3 days in 4% paraformaldehyde,the brains were sagitally cut into 5-um-thick sections, and the sections were stored in fridge at 4℃for SP immunohistochemistry.5 Statistics analysisAll the results were presented as mean±tandard deviation, using SPSS16.0 statistical software, One Way Analysis of Variance and LSD-t test were used, P< 0.05 was considered as statistically significant.Results1 Serum TT4 were decreased significantly below normal values(TT4 45.11±0.43μg/L) in newborns of hypothyroid mothers(TT4 16.83±0.45μg/L) (P<0.001),However, serumTT4 in newborns of hyperthyroid mothers (TT4 103.50±2.37μg/L) were increased significantly than normal values (P<0.001).2 SerumTT3 were decreased significantly below normal values(TT3 844.57±20.85ng/L)in newborns of hypothyroid mothers(TT3 142.35±7.76ng/L) (P< 0.00),However, serumTT3 levels in newborns of hyperthyroid mothers (TT3 1269.63±32.18ng/L) were increased significantly than normal values (P<0.001).3 Brain VEGF were decreased significantly below normal values(VEGF 11.15±1.33 ng/ml) in newborns of hypothyroid mothers(VEGF 8.69±0.48 uglL) (P<0.001),However, brain VEGF in newborns of hyperthyroid mothers (VEGF53.46±10.62 ug/L) were increased significantly than normal values (P<0.001).4 The expression of VEGF in the germinal matrix region were decreased significantly below normal values(OD 0.14±0.02 A) in newborns of hypothyroid mothers(OD 0.03±0.01 A) (P<0.001),However, the expression of VEGF in the germinal matrix region in newborns of hyperthyroid mothers (OD 0.32±0.06 A) were increased significantly than normal values (P<0.001).Conclutions1 Offer thyroid hormone (T4) to female rats of pregnancy can significantly raise serum T4 and T3 levels of newborn rats. It shows thyroid hormone can permeate placenta protective screen.2 Offer thyroid hormone (T4) to female rats of pregnancy can significantly raise brain VEGF levels of newborn rats. It shows thyroid hormone has a substantial impact on vasculature development in the brain of newborn rats.3 The expression of VEGF in the germinal matrix region in newborns of hyperthyroid mothers were increased significantly than normal values, It shows that thyroid hormone is a contributing factor to brain angiogenesis in the germinal matrix region. |
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