Effect of protein malnutrition and maternal caffeine intake on the growth of fetal rat brain

Pregnant dams were divided into two subgroups on day 10 of gestation. Half were fed a 20% protein diet and the other half an 8% protein diet. A second group also subdivided was pair-fed with rats of the first group. Their diet was supplemented with caffeine in amount calculated to provide daily doses of 2 mg/100 g body weight. On days 18, 20, and 22 randomly selected dams were injected with 3H-thymidine intraperitoneally and 1.5 h later their fetuses were delivered surgically in order to determine the rate of DNA synthesis along the gestation. The rest of the fetuses were delivered surgically on day 22. Pups' brains were rapidly removed and DNA, RNA, protein and 3H-thymidine uptake were studied. Average body weights of the fetuses in the caffeine-supplemented control group were smaller than those of the noncaffeine group. Effects of caffeine that were similar in both diet groups included a decrease in brain DNA content and concentration and an increase in brain protein content and concentration. However, the percent decrease and increase, respectively, was different depending on the nutritional status. DNA synthesis was not affected by malnutrition or caffeine supplementation on day 18 of gestation. Caffeine's effect on the rate of DNA synthesis was different on day 20 of gestation depending on nutritional status. Caffeine supplementation resulted in a decrease in DNA synthesis in both groups on day 22 of gestation. These data indicate that caffeine intake during pregnancy produces differential effects on fetal rat brain depending on dietary protein content.     

Maternal caffeine ingestion increases the tyrosine level in neonatal rat cerebrum

The cerebral free amino acids in neonatal rats, from dams given 0.04% caffeine in the drinking fluid ad libitum before and/or during pregnancy throughout the lactational period, were examined on days 1, 5 and 10. Significantly reduced cerebral weight was observed on day 1 with a mean caffeine level of 7 micrograms/g wet weight. The tyrosine concentration in the cerebrum, but not that in the liver, was increased on days 1 and 5 with approximate mean caffeine levels of above 1.5-2.0 micrograms/g wet weight. The tyrosine level showed a positive correlation with the caffeine level in neonatal cerebrum only on day 1 in the group with caffeine ingestion after pregnancy. There was no significant increase in the fetal cerebral concentration of MOPEG-SO4 on day 5 with maternal caffeine. These results suggest that maternal caffeine disturbs the neonatal cerebrum through tyrosine and tyrosine hydroxylase, and then produces behavioral abnormalities in developing rats.     

Chronic caffeine intake by rat dams during gestation and lactation affects various parts of the neonatal brain

Timed-pregnant rats were randomly divided into 2 groups on day 13 of gestation. Group 1 received a 20% protein diet. Group 2 was pair-fed to group 1 with a 20% protein diet containing caffeine (1 mg/100 g body weight). At parturition, the dams of each group were continued on their respective diets until day 22 postpartum. At the time of weaning (day 22), only male rats were continued in the study. At this time, rats from both groups were fed the control diet containing 20% protein. On day 57 and 58, rats were killed, the brains divided into six areas, and DNA, RNA and protein contents were measured. In certain areas of the brain, weight, cholesterol, DNA, RNA and protein contents were different even long after returning to the caffeine-free control diet. The present study demonstrates that even if a relatively small amount of caffeine is taken during gestation and lactation, a time during which the growth rate is greater than in any other period of life, certain areas of the brain may be affected. These findings suggest that future central nervous system impairment may be expressed later in life in these offspring.     

Perinatal respiratory control and its modulation by adenosine and caffeine in the rat.

The perinatal development of respiratory rhythm generation and its modulation by adenosinergic drugs have been examined in rats from embryonic d 18 (E18) to postnatal d 3 using an in vitro brain stem-spinal cord preparation. Generation of rhythmic respiratory activity in the medulla oblongata and inhibition of this activity by pontine structures were evident on E18. The adenosine A(1)-receptor agonist, N(6)-(2-phenylisopropyl) adenosine, R (-) isomer (R-PIA) (1 microM), induced an age-dependent reduction of respiratory frequency that could be reversed by the adenosine antagonist theophylline (55 microM). The effect of R-PIA was reduced 24 h after birth compared with E21 and 2 h postnatal age. In preparations from pups that had been exposed to a low dose of caffeine (0.3 g/L in drinking water to dams), pontine inhibition of respiratory rhythm generation in the medulla was more pronounced. When the pons was removed, the respiratory frequency was higher than in the control group. Adenosine A(1)-mRNA and A(1)-receptor development in pons and medulla were studied, and by E18, mRNA, receptor protein, and functional coupling to G-proteins were confirmed using guanylyl-5'-O-(gamma-[(35)S]thio)-triphosphate binding. There were no major changes in receptor numbers or distribution of A(1) receptors or mRNA in rat pups subjected to caffeine exposure. We conclude that respiration is already modulated by adenosine A(1) receptors at the level of the medulla oblongata in the fetal period in an age-dependent manner. Furthermore, long-term maternal caffeine intake during gestation seems to increase the pontine inhibition of, and the activity of, respiratory rhythm-generating neuronal networks in medulla oblongata without detectable changes in expression of A(1)-receptor number or A(1)-receptor mRNA.     

Effects of orally administered caffeine on cellular response in protein energy-malnourished neonatal rat brain

The purpose of this study was to determine the effects of caffeine on growing rats and how protein energy malnutrition can modify these potential effects. Caffeine (1,3,7-trimethylxanthine) is not only the most commonly consumed, neurally active stimulant in our daily lives, but it is widely used in the management of apnea in the premature neonate. One group of dams (20%) (n = 6) was begun on a 20% protein diet ad libitum. The second group (6%) (n = 4) was begun on a 6% protein diet. A third group (20% + C) (n = 4) was pair-fed to group 1 (20%) with the 20% protein diet, but beginning on day 3 the pups received 10 mg/kg body weight of caffeine via intragastric feeding needle every other day. The fourth group (6% + C) (n = 5) was pair-fed with group 2 (6%) with the 6% protein diet and the pups received 10 mg/kg of caffeine in the same manner as the 20% + C group from day 3. Although the 6% protein diet was associated with the expected reduced body and brain growth, there were no additional growth alterations associated with caffeine administration in either the 20% or 6% diet groups. This growth failure was accompanied by the expected reductions in total whole brain DNA, RNA, protein, and cholesterol content regardless of whether caffeine was received or not. Effects of caffeine which were similar in both diet groups included an increase in brain RNA content and concentration and an increase in the RNA/DNA ratio. However, there were differential effects of caffeine seen depending on diet group assignment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synergistic effects of thyroxine and dexamethasone on enzyme ontogeny in rat small intestine.

The synergistic effects of dexamethasone (DEX) and thyroxine (T4) on the postnatal maturation of the 13-d-old rodent small intestine has been studied. Previous studies have shown that hydrocortisone and T4 produced a synergistic response in enzyme maturation. However, T4 elevates corticosteroid-binding globulin, which reduces the clearance of hydrocortisone. Thus, the apparent synergy between T4 and hydrocortisone may have been due to increased glucocorticoid availability. DEX, which does not bind to corticosteroid-binding globulin, was given (d8-12) at 25 pmol (i.e. 0.01 micrograms)/g body wt/d as established by a dose-response study in which this dose of DEX induced one third the maximum response in sucrase activity. In this way, synergy with T4 (130 pmol/g body wt/d, i.e. 0.1 micrograms/g body wt/d, d 5-12) could still be observed. Glucoamylase, lactase, acid beta-galactosidase, alkaline phosphatase, and sucrase activities were determined in two regions of the small intestine. Overall, the results for the two hormones administered alone showed intestinal maturation to be not significantly affected in the T4 group and partially stimulated in the DEX group. When combined, DEX + T4 synergistically increased jejunal sucrase, ileal glucoamylase, and duodenal alkaline phosphatase, and lowered ileal acid beta-galactosidase. The striking exceptions to the general pattern were two brush border enzymes that normally decline during intestinal maturation, namely ileal alkaline phosphatase and jejunal and ileal lactase. For these enzymes, DEX alone did not elicit precocious maturation, and there was no evidence for a synergistic interaction of these two hormones. Serum corticosterone concentrations also were measured. When corticosterone concentrations were compared with enzyme activity, no correlation was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of prenatal exposure to structurally diverse chemicals on the ontogeny of rat dehydrogenases

Activity levels of sorbitol dehydrogenase (SDH), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH) were measured in the livers and brains of rats treated prenatally with 3,4,3',4'-tetrachlorobiphenyl (4CB, 3 mg/kg/day), diethylstilbestrol (DES, 10 micrograms/kg/day), zeranol (ZN, 4mg/kg/day), and cadmium (Cd, 25 mg/kg/day) and compared with enzyme levels for control groups. Enzyme activities were measured at days 15, 17, 19, and 21 prenatally, and days 1, 5, 10, 21, 35, and 56 postnatally. SDH activity was not altered by treatment with 4CB, DES, or ZN, but Cd produced reduced levels in both liver and brain of sexually mature offspring. The patterns of LDH and G6PDH, including sexual differentiation of the latter in adult liver, were not affected by any of the treatments in either tissue. The developmental profiles of each of these enzymes in untreated animals is unique, suggesting that a similar catalytic mechanism is not a factor in determining the patterns of their developmental accumulation.     

新生大鼠反复惊厥对皮质区糖皮质激素受体表达的影响

目的：研究新生期反复惊厥对大鼠大脑皮层内糖皮质激素受体（glucocorticoid receptor, GR）表达的影响。方法：生后（postnatal,PN）7 d的Sprague-Dawley大鼠48只,随机分成两组,惊厥组每日吸入三氟乙醚诱导惊厥发作1次,每次持续30 min,连续6 d;对照组同样操作但不吸入三氟乙醚。分别于PN 13 d、15 d和19 d每组各处死8只大鼠,Western blot法和免疫组化法观察大鼠大脑皮层GR表达的变化。结果：与对照组相比,在PN-15 d时惊厥组大鼠大脑皮层胞浆中GR的表达明显下调（P<0.01）,在PN-15 d、PN-19 d时胞核中GR表达水平明显下调（P<0.05）。与对照组相比较,PN-13 d时,惊厥组大鼠顶叶区GR免疫化学累积光密度（AOD）明显降低（P<0.05）;PN-15 d时,惊厥组大鼠皮层顶叶区GR免疫化学AOD明显降低（P<0.01）;PN-19 d时,惊厥组大鼠皮层顶叶、颞叶、额叶区GR免疫化学AOD明显降低（P<0.01）。结论：新生大鼠反复惊厥造成皮质GR表达的异常,可能参与发育期脑损伤。［中国当代儿科杂志,2010,12（1）：47-50］     

Maternal nicotine effects on vascular endothelial growth factor expression and morphometry in rat lungs

Aims

Maternal smoking during pregnancy may impair pulmonary function in infants, and the exact mechanisms underlying these changes are unknown. We evaluated the effects of maternal nicotine exposure on lung VEGF expression and morphometry during the postnatal period in rats.

Methods and results

Timed pregnant Sprague–Dawley rats were injected subcutaneously with nicotine at a dose of 2 mg/kg/day from Day 3 to Day 21 of gestation. A control group was injected with saline. Body weight, lung weight, and lung volume were comparable between control and nicotine-exposed rats. Plasma vascular endothelial growth factor (VEGF) levels and lung VEGF mRNA expression decreased with advancing age, and nicotine exposure insignificantly decreased plasma VEGF levels and lung VEGF mRNA expression, compared with the control rats during the study period. Nicotine exposure caused a significant decrease in vascular endothelial growth factor receptor (VEGFR)-2 mRNA expression, compared with the level of the control rats on Postnatal Day 1. On Postnatal Day 1, nicotine-exposed rats exhibited a significantly lower volume fraction of alveolar airspace and alveolar surface area and a significantly higher alveolar wall volume fraction than did the control rats.

Conclusions

Maternal nicotine exposure during pregnancy decreases VEGF and VEGFR-2 mRNA expression and alters lung structure in the lungs of postnatal rats. Because angiogenesis is vital for alveolarization during normal lung development, these results suggest that decreased VEGF expression might be involved in the structural alterations of the developing lung after exposure to antenatal nicotine.     

Effect of sympathectomy on ontogeny of small intestinal disaccharidases in the rat

In the present study the effect of chemical sympathectomy on the development of small intestinal enzymes in the rat was analyzed. Eight doses of guanethidine sulfate were administered subcutaneously every 48 h to 34 newborn rats, starting at birth. The last dose was given at 14 days of age. Twenty-two littermates served as controls. Intestinal lactase, maltase, sucrase, and alkaline phosphatase were determined at 15, 17, 20, 23, and 25 days of age. Sympathectomy was demonstrated by reduction of the number of perikarya in the superior cervical ganglia in treated rats as compared with control rats. A normal developmental pattern of activities of the disaccharidases in the small intestine was observed in both groups. The activity of alkaline phosphatase was significantly lower (p less than 0.01) in the 15- and 17-day-old treated animals.     

Theophylline effects on cellular response in protein-energy malnourished neonatal rat brain

The present study employed an animal model in an attempt to document effects on brain growth of long-term exposure to theophylline in the presence or absence of malnutrition. One group of dams was randomly divided into half. One-half was fed a 20% protein diet and the other half a 6% protein diet. Similarly, a second group of dams was also randomly divided into two groups. These were pair-fed with rats of the first group, receiving diets comparable to those in group one but to which theophylline was added in amounts calculated to provide daily doses of 2 mg/100 g of body weight. Theophylline supplementation in the dams' 6% protein diet decreased the body weight of the pups consistently from d 3 to the end of the study at d 15 in comparison to the non-theophylline group. In contrast, the presence of theophylline in the control diet increased the body weight of the pups at d 15 compared with that of the non-theophylline group. Brain weight was essentially identical in the normal controls and the normally nourished group given theophylline. No difference in brain weight was noted between the malnourished group and the malnourished group given theophylline. We found a significant reduction in DNA content per brain or per mg of brain weight in the normally nourished group given theophylline compared with non-theophylline group. DNA values per mg of brain weight from the controls that received theophylline were not different from either malnourished group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maternal treatment with propofol attenuates lipid peroxidation after transient intrauterine ischemia in the neonatal rat brain

The purpose of this study was to investigate whether propofol has a neuroprotective effect on the fetal brain after intrauterine ischemia-reperfusion (I/R) injury in the rat fetus. Fetal brain ischemia was induced by clamping the utero-ovarian artery bilaterally for 30 min and reperfusion was achieved by removing the clamps for 2 h. A 40-mg/kg single dose of propofol was administered intraperitoneally 15 min before I/R injury. Lipid peroxidation in the brain tissue was determined as the concentration of thiobarbituric acid reactive substances (TBARS) for each fetal rat. Results showed that lipid peroxidation byproducts increased after I/R injury. Maternal treatment with propofol reduced TBARS compared to the I/R group. Propofol has been shown to have neuroprotective effects in intrauterine I/R-induced fetal brain damage in rats.     

新生大鼠反复惊厥对脑内γ-氨基丁酸A受体α1和β2亚单位表达的短期影响

目的γ-氨基丁酸A受体(GABAAR)作为脑内最重要的抑制性受体在脑功能中起重要作用。该实验通过研究新生期反复惊厥对大鼠脑内GABAARα1和β2亚单位表达的短期影响,探讨其与发育中脑损伤的关系。方法生后7d的Sprague-Dawley大鼠随机分成两组,每组32只,惊厥组每日吸入三氟乙醚诱导惊厥发作1次,每次持续30min,连续6d;对照组同样操作但不吸入三氟乙醚。分别于反复惊厥后1d和7d每组各处死16只大鼠,每个时间点分别采用免疫组化方法和Western blot方法观察大鼠大脑皮层及海马GABAARα1和β2亚单位表达的变化。结果反复惊厥后1d时,在惊厥组大鼠顶叶及海马齿状核、CA3和CA4区GABAARα1亚单位免疫化学累积光密度(AOD)较对照组明显增高(P<0.05),反复惊厥后7d时,在惊厥组大鼠顶叶及海马齿状核、CA1至CA4区GABAARα1亚单位免疫化学AOD较对照组明显增高(P<0.05),反复惊厥后1d和7d时,在惊厥组大鼠大脑皮层和海马区GABAARα1亚单位蛋白表达均明显高于对照组(P<0.01)。反复惊厥后7d时,在惊厥组大鼠海马CA1、CA2区GABAARβ2亚单位免疫化学AOD明显高于对照组(P<0.05),在丘脑区明显低于对照组(P<0.05),惊厥组大鼠海马区GABAARβ2亚单位蛋白表达明显高于对照组(P<0.05)。结论新生大鼠反复惊厥造成脑内GABAARα1和β2亚单位表达的短期改变,这种改变可能参与发育期惊厥性脑损伤。     

Association between adenosine receptor gene polymorphism and response to caffeine citrate treatment in apnea of prematurity; An Egyptian single-center study

Background

Caffeine citrate is the methyl-xanthine of choice used in controlling apnea of prematurity (AOP). Caffeine central effect is mediated via non-selective (A₁) and selective (A_2a) adenosine receptors antagonism. Variability in caffeine response had been frequently noticed in AOP, suggesting underlying genetic predisposition.

外源性bFGF对缺氧缺血新生大鼠脑c-Fos表达影响的研究

探讨外源性碱性成纤维细胞生长因子(bFGF),对缺氧缺血性脑损伤(HIBD)新生大鼠脑c-fos基因蛋白产物(c-Fos)表达影响,研究原癌基因c-fos表达与HIBD的关系,采用免疫组织化学染色及定量图像分析方法,观察c-Fos表达强度、染色灰度及面积的变化.结果显示正常生后7-14 d新生大鼠脑有c-Fos表达,以生后10 d最为明显;缺氧缺血20min后即刻c-Fos表达增强,并于缺氧缺血后4 h达高峰,持续至72 h;脑内不同部位c-Fos表达时间、强度、灰度及面积不同.连续腹腔注射外源性bFGF 3 d后鼠脑c-Fos表达增强.结论外源性bFGF可增强HIBD新生大鼠脑c-Fos的表达,bFGF及c-fos基因可能参与HIBD修复的病理生理过程.     

The metabolic effects of caffeine in the newborn infant

We studied the effects of intravenous administration of 20 mg/kg caffeine citrate on glucose homeostasis, cardiorespiratory status, and urinary excretion of catecholamines and electrolytes in 12 premature infants with recurrent apnea. Six infants received intravenous dextrose (5% or 10% in 0.225% saline) during the study, and six were fed formula every 3-4 hours. In the intravenously fed infants, the plasma glucose concentration postcaffeine did not vary significantly from the precaffeine level of 73 +/- 3.2 mg/dl (mean +/- SEM) at 0.5, 1, and 1.5 hours. However, in the formula-fed infants, there was a consistent fall in plasma glucose levels after caffeine administration. This decrease from a precaffeine level of 99 +/- 12 mg/dl (mean +/- SEM) approached statistical significance at 0.5 hours (P = 0.07), and was significantly lower at 1 and 1.5 hours (P less than 0.02). In five infants, cardiorespiratory status and urinary excretion of catecholamines and electrolytes were evaluated for 12-hour periods before and after caffeine administration. There was a significant reduction in the number of apneic episodes following caffeine administration; however, caffeine did not appear to affect mean heart rate or urinary excretion of sodium, potassium, epinephrine, norepinephrine, or dopamine. Our data suggest that the effects of caffeine on glucose homeostasis may vary with the nature and/or route of substrate administration.     

The effects of caffeine on the preterm sheep ductus arteriosus

Caffeine and other methyl xanthines are widely used in the neonatal period. A recent, randomized, placebo-controlled, multicenter trial found that infants who were randomly assigned to caffeine treatment had less need for pharmacologic and/or surgical closure of a patent ductus arteriosus (PDA). We hypothesized that the decreased need for pharmacologic and surgical closure of the PDA after caffeine treatment might be due to a direct effect of caffeine on ductus contractility. We examined preterm fetal lamb ductus arteriosus (from 24 fetuses, 105 +/- 4 d of gestation, term = 147 d), in vitro to determine the direct effects of caffeine on the isometric tension of the ductus arteriosus. Caffeine (0.003-0.3 mM) had no direct effect on ductus arteriosus tension, nor did it affect the contractile response of the ductus arteriosus to increasing oxygen concentrations. Caffeine's lack of effect was observed in both the presence and absence of indomethacin and NG-nitro-L-arginine methyl ester (L-NAME) (inhibitors of prostaglandin and nitric oxide production). In conclusion, we found no evidence of a direct effect of therapeutic caffeine concentrations on ductus contractility.     

Atrial natriuretic polypeptide in the fetal rat: ontogeny and characterization

The presence of immunoreactive atrial natriuretic polypeptide (ANP) has been demonstrated in fetal atria early in gestation but further definition of fetal ANP has not been reported. To characterize the principal molecular forms of fetal ANP and to compare fetal ANP to that of the adult of the same species, we extracted the atria of pregnant adult and 20-day fetal rats, the hearts of 14-day fetuses, and intact 12-day fetuses in 1 M acetic acid. Tissue collected from littermates was pooled. We measured ANP by radioimmunoassay before and after gel filtration on Sephadex G-75 in each group. ANP concentrations (means +/- 1 SD) in ng/mg protein and ng/animal were 1296 +/- 505 and 7707 +/- 1877 in adult atria (n = 17), 174 +/- 44 and 62 +/- 13 in 20-day fetal atria (n = 7), and 33 +/- 5.3 and 3.7 +/- 0.9 in 14-day fetal hearts (n = 6), respectively. Acid extracts from intact 12-day fetuses did not dilute in parallel to the standard curve; therefore, concentrations of ANP for the 12-day fetuses are not reported. ANP concentration rose from the 20-day fetus to the adult (p less than 0.0001). The major species of ANP eluting from the Sephadex column had an apparent molecular weight of 16 K in all groups. We conclude: 1) ANP is present in the fetus shortly after the completion of organogenesis; 2) 16 K ANP is the principal intracardiac species in the fetus and the adult; and 3) the existence of ANP soon after cardiac development suggests a possible role for ANP in fetal blood pressure and sodium and water homeostasis.