Ultrastructural changes in female germ cells during the meiotic prophase in the rat: a special study of membranes after cryofracture

Ultrastructural changes in the nuclear and cytoplasmic elements in the germ cells of female rats were followed before meiotic prophase (15.50 days post-co?tum and 17.25 days post-co?tum) and during it (17.75 days post-co?tum to birth). We observed: modifications in the nuclear envelope which was thick during the oogonial stage, becoming thinner when the chromosomes entered preleptotene stage. The thinning of the envelope was due to the disappearance of the chromatin material lining it; variations in the number and distribution of germ cell nuclear pores according to stage; the pores were first scattered in small clusters of 6 to 8 over the entire nuclear membrane. From the preleptotene to zygotene stage, these clusters enriched in pores to form large areas. Finally, in the pachytene and diplotene stages, clusters of more than 100 pores were seen; nucleolar fragmentation from the preleptotene stage, followed by the formation of a new active nucleole in the diplotene; polarization of the mitochondria in the oldest oogonia just before the beginning of meiotic prophase. This polarization disappeared after the onset of the meiotic processes, then appeared again near the developing Golgi apparatus at the end of the pachytene stage; the formation of large gap junctions and numerous bands of tight junctions between the somatic cells; these formations contrasted with small gap junctions, and the tight junctions became scarce just before the meiotic process began. These observations, as well as those concerning nuclear pore distribution were made using the cryofracture technique.     

Allosteric activation of brain hexokinase by magnesium ions and by magnesium-ion–adenosine triphosphate complex

1. The highest blood concentrations of ketone bodies were found at 5 days of age, after which time the concentration fell to reach the adult value by 30 days of age. 2. Both mitochondrial and cytoplasmic hydroxymethylglutaryl-CoA synthase activities were detected, with highest activities being found in the mitochondria at all stages of development. Activity of the mitochondrial enzyme increases rapidly immediately after birth, showing a maximum at 15 days of age, thereafter falling to adult values. The cytoplasmic enzyme, on the other hand, increased steadily in activity after birth to reach a maximum at 40 days of age, after which time activity fell to adult values. 3. Both mitochondrial and cytoplasmic aceto-acetyl-CoA thiolase activities were detected, with the mitochondrial enzyme having considerably higher activities at all stages of development. The developmental patterns for both enzymes were very similar to those for the corresponding hydroxymethylglutaryl-CoA synthases. 4. The activity of heart acetoacetyl-CoA transferase remains constant from late foetal life until the end of the suckling period, after which time there is a gradual threefold increase in activity to reach the adult values. The activity of brain 3-oxo acid CoA-transferase increases steadily after birth, reaching a maximum at 30 days of age, thereafter decreasing to adult values, which are similar to foetal activities. Although at all stages of development the specific activity of the heart enzyme is higher than that of brain, the total enzymic capacity of the brain is higher than that of the heart during the suckling period.     

The fetal and postnatal development of small intestinal disaccharidases in the rabbit

The development of small intestinal enzymes (lactase, acid- and hetero beta-galactosidases, cellobiase, maltase, trehalase, and sucrase) was studied from 18 days after conception until birth in 24 rabbit fetuses, and during the postnatal period in 15 newborn, juvenile, and adult rabbits. Lactase, acid- and hetero beta-galactosidases, cellobiase, and trehalase activities increased significantly during the fetal stage, while changes in sucrase and maltase activities were not substantial. In the postnatal period, lactase and cellobiase activities decreased significantly whereas maltase, sucrase, and trehalase activities increased significantly to reach adult values by 30 days of age. The acid- and hetero beta-galactosidases remained unchanged.     

Mitochondrial activity of rat kidney during ontogeny

The development of oxidative metabolism was studied from the late fetal to adult stages in mitochondria isolated from rat kidney. We used the oxygen consumption rate, as an index of inner membrane activity and citrate synthase and fumarase activities as an index of matrix activity and cytochrome c oxidase activity as an index of the number of mitochondria. Fumarase and citrate synthase activities displayed different developmental patterns, suggesting that these Krebs cycle enzymes did not mature synchronously. In fetal mitochondria, net oxygen consumption measured in the presence of succinate or glutamate as substrate, was low; it increased during the day after birth and reached adult level between days 10 and 15. During this period, the levels of citrate synthase and cytochrome c oxidase activity did not change significantly in the isolated mitochondrial fraction. However, in fetal and adult kidney homogenates, these levels increased four-fold, suggesting a corresponding increase in the number of mitochondria. Most of these increases occurred during the 15 days after birth. These results suggest that in rat kidney, mitochondrial maturation precedes the maturation of reabsorptive ion transport and does not limit its development.     

Urea biosynthesis in normal human fetuses

Normal human fetuses at different gestation periods were collected on ice after hysterotomy and the enzymes of the urea cycle were measured in the liver. The activity of all enzymes increased with increasing gestational age towards the adult value, however, in no case did the values reach the normal adult level. The bladder fluid of these fetuses contained urea and ammonia nitrogen at concentrations which were akin to the concentrations found in fetal blood. The ornithine transcarbamylase activity was the lowest when compared to the adult values and appeared to be the rate-limiting enzyme in the cycle, along with argininosuccinic acid synthetase activity, which was also very low. The activity of arginase was found to be the highest in the cycle. The very low ornithine transcarbamylase and argininosuccinic acid synthetase activities and the comparatively higher arginase activity migh lead to the channeling of ornithine into alternate metabolic pathways.     

Changes in hepatic lipogenesis during development of the rat

1. Changes in the activities of ATP citrate lyase, ;malic' enzyme, glucose 6-phosphate dehydrogenase, pyruvate kinase and fructose 1,6-diphosphatase, and in the ability to incorporate [1-(14)C]acetate into lipid have been measured in the livers of developing rats between late foetal life and maturity. 2. In male rats the activities of those systems directly or indirectly concerned in lipogenesis (acetate incorporation into lipid, ATP citrate lyase and glucose 6-phosphate dehydrogenase) fall after birth and are maintained at a low value until weaning. After weaning these activities rise to a maximum between 30 and 40 days and then decline, reaching adult values at about 60 days. ;Malic' enzyme activity follows a similar course, except that none could be detected in the foetal liver. Pyruvate kinase activity is lower in foetal than in adult livers and rises to slightly higher than the adult value in the post-weaning period. Fructose 1,6-diphosphatase activity rises from a very low foetal value to reach a maximum at about 10 days but falls rapidly after weaning to reach adult values at about 30 days. 3. Weaning rats on to a high-fat diet caused the low activities of acetate incorporation, ATP citrate lyase, glucose 6-phosphate dehydrogenase and pyruvate kinase, characteristic of the suckling period, to persist. ;Malic' enzyme and fructose 1,6-diphosphatase activities were not altered appreciably. 4. No differences could be detected in hepatic enzyme activities between males and females up to 35 days, but after this time female rats gave higher values for acetate incorporation, glucose 6-phosphate dehydrogenase activity and ;malic' enzyme activity. 5. The results are discussed in relation to changes in alimentation and hormonal influences.     

Nutritional control of respiratory and other muscular activities in relation to plasma prostaglandin E in the fetal sheep

The effects of nutrient availability on fetal plasma prostaglandin E (PGE) concentrations, on fetal breathing movements and electromyographic (EMG) activities of fetal nuchal and forelimb muscles were investigated in pregnant ewes by varying dietary intake and by manipulation of fetal plasma glucose concentration. The incidence of fetal breathing movements (06.00-10.00 h) decreased with increasing gestational age while fetal arterial concentrations of plasma PGE increased significantly over the same period of gestation. Maternal fasting for 48 h reduced the incidence of fetal breathing movements and the amount of nuchal EMG activity (06.00-10.00 h) in animals older than 130 days but had no effect earlier in gestation. No changes in forelimb EMG activity were observed during fasting at any gestational age. Plasma PGE levels increased significantly during fasts begun both before and after 130 days of gestation. When data from fed and fasted states were combined for all fetuses, irrespective of gestational age, there was a significant inverse correlation between fetal breathing movements incidence and plasma PGE concentration in utero. This relationship was even more pronounced when the fetuses were considered individually. Insulin infusions induced hypoglycaemia, an increase in fetal plasma PGE concentration and a significant reduction in the incidence of fetal breathing movements at all ages. Glucose infusions of fetal breathing movements only after 130 days and had no effect on plasma PGE levels in utero at any gestational age. Neither insulin nor glucose infusions altered the EMG activities of the nuchal and forelimb muscles. The results show that glucose availability is an important factor in determining the incidence of fetal breathing movements in utero and indicate that nutritionally induced changes in fetal breathing movements are mediated in part by PGE. They also suggest that PGE is a physiological regulator of fetal breathing movements in the sheep during late gestation.     

CHANGES DURING DEVELOPMENT OF MOUSE BRAIN IN THE ACTIVITIES AND SUBCELLULAR DISTRIBUTIONS OF CREATINE AND ADENYLATE KINASES

Abstract— The activities and electrophoretic patterns of creatine (CK) and adenylate (AK) phosphokinases were determined in the mitochondrial and high speed supernatant fractions of developing and adult mouse brain. The CK activity of the cytosol increases three-fold between 9 and 19 days of age and four-fold by 29 days. Mitochondrial CK activity increases from birth to reach a maximum four-fold that at birth by 19 days of age. The developmental changes in soluble AK activity parallels that of CK. Although the increase in CK activity of the mitochondria exceeds that of the mitochondrial proteins during the period of rapid brain development, mitochondrial AK specific activity changes little. No major changes were found during development in the electrophoretic patterns of proteins with CK or AK activity in the supernatant and mitochondrial fractions. The changes in mitochondrial CK and AK activity parallel the change from a predominantly glycolytic to an aerobic mode of brain metabolism and support the concept that these enzymes play an important role in mitochondrial energy metabolism. Soluble CK and AK activity increase concomitant with neuronal maturation and the associated greatly increased need for rapidly available high energy phosphate.     

Strontium-85 in the fetuses of pregnant rats and mice

Pregnant SPF Wistar rats and ICR/Swiss albino mice were injected in the tail vein with 85SrCl2 with 0.05 mM inactive carrier (SrCl2) given in volumes of 0.1 ml. The activity in the injected volume was about 14 MBq per kg of rat and 13 MBq per kg of mouse. The animals were injected at 2 or 13 days of gestation. The activity retained by the fetuses was quantitatively determined at three stages of the fetal intrauterine development: in rats at 14, 16 and 21 days of gestation, in mice at 14, 16 and 20 days of gestation. The activity of fetuses and/or placentas with fetal membranes was measured using a TESLA automatic gamma counter. Results indicate that fetuses of mice retained a significantly (P less than 0.01) greater percent of strontium activity than fetuses of rats. The highest specific activities (the percentage of total activity retained per gram of fetal tissue) were found in the late pregnancy period (at 21 days of gestation in rats and 20 days of gestation in mice) in animals that were injected with the radionuclide at 13 days of gestation.     

Development of the metanephric kidney. Protein and nucleic acid synthesis

The metanephric kidney was studied in fetal and older mice beginning at 16 days after mating of the parents. Polyribosomes from fetal kidneys labeled in vitro with 14C-labeled amino acids had 10-20 times more acid-precipitable radioactivity associated with them than polysomes from adult kidneys similarly labeled. Between 3 and 6 days after birth the rate incorporation of labeled amino acids by polyribosomes from neonatal kidneys declined sharply to only twice the value found for adult kidneys. There was no change in the shape of the polyribosome profile with increasing age, but before birth few, if any, ribosomes were bound to membranes compared with 20% 2 days after birth and between 20 and 30% in the adult. Total protein represented less than 10% of the wet weight in the fetal kidney but increased to 17% of the wet weight in the adult kidney. There was a steady decline in the concentration of RNA and DNA with respect to dry weight throughout kidney development. DNA concentration declined more rapidly than RNA concentration, so that the milligram to milligram ratio of RNA to DNA increased. In males the RNA/DNA ratio was stable at 1.3 at 40 days after birth; but in females the decline in DNA concentration was more protracted, and at 200 days after birth the RNA/DNA ratio was only 0.99. Thus, total nucleic acids show only gradual changes in concentration throughout development of the kidney, but a sharp change in the synthetic activity of the ribosomes and in their binding to membranes occurs in kidneys soon after birth.     

Amelioration of some metabolic effects produced by hyperthyroidism in late pregnant rats and their fetuses. Effects on lipids and proteins.

We have studied the effect of 40-45 days administration of 1 mg/kg thyroxine on protein and lipid metabolism in liver, heart, lungs, kidneys and adrenal glands of virgin and 21-day pregnant rats and their fetuses and placentae. The chronic administration of thyroid hormone produced significant increases in serum T3 and T4 in both groups as well as in organ weights and protein concentrations in virgin rats, but much smaller modifications in pregnant ones. Hyperthyroidism decreased the weight of fetal livers and increased that of placentae; protein content was increased in all fetal organs. Hyperthyroidism induced increases in phospholipid concentrations in all the organs and in total lipids only in liver and heart of adult rats, which were not counteracted by pregnancy. Pregnant rats had increases in total lipids in liver and kidneys and in adrenal phospholipids. In hyperthyroid fetuses there was an increase in hepatic total lipids and no changes in phospholipids. Hepatic lipogenesis (measured by in vivo incorporation of 3H2O into lipids) was increased by hyperthyroidism in virgin and pregnant rats, but the increase was significantly smaller in the pregnant hyperthyroid rats compared with the virgin ones. Fetal lipogenesis in liver and lung was not changed. In addition, an increase was observed in lipogenic enzyme (fatty acid synthetase and glucose-6-phosphate dehydrogenase) activities in hyperthyroid virgin rats which was prevented by pregnancy. In fetuses only pulmonary glucose-6-phosphate dehydrogenase was increased when expressed in terms of tissue weight. Our results indicate that the metabolic effect of hyperthyroidism is attenuated in pregnant rats and their fetuses, when compared with adult virgin rats, in most of the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Subacute inhalation of cigarette smoke by pregnant and lactating rodents: AHH changes in perinatal tissues

To study the transplacental acquisition of tobacco smoke products and the effects on fetal tissue enzymes, pregnant rats, guinea pigs, and hamsters were exposed to freshly generated cigarette smoke via a nose-only inhalation system on a daily basis through the latter one-third (guinea pigs) or latter half (rats, hamsters) of the gestational period. Following euthanasia on the day of parturition, microsomal aryl hydrocarbon hydroxylase (AHH) activities were determined in the lungs, livers, and kidneys of both dams and fetuses. The possible acquisition of tobacco smoke products via the milk was studied by exposing lactating dams to cigarette smoke daily for either 4 or 14 days (rats), 4 or 7 days (guinea pigs), or 10 days (hamsters), with analysis of tissues from the euthanized pups for AHH. Pups were also exposed directly (nose only) to cigarette smoke. In the treated pregnant and lactating rat, maternal pulmonary, hepatic, and renal AHH was significantly increased but only fetal lung and the liver of 14-day-old pups showed a marked induction of AHH activity. In the pregnant and lactating guinea pig, only the pulmonary and renal AHH activities were increased following exposure, whereas in the fetuses and nursing pups, none of the tissue AHH activities was significantly altered by exposure. In the pregnant and lactating hamster, only the pulmonary AHH was increased following exposure to cigarette smoke, whereas the activity in fetal and pup tissues remained unchanged from the levels observed in control animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of maternal diabetes on the development of carbohydrate metabolizing enzymes in fetal rat liver

Effects of streptozotocin-induced maternal diabetes on fetal hepatic carbohydrate-metabolizing enzyme development and hormonal status has been explored in the rat. Hepatic glycogen synthase a activity of the normal fetus rose to a maximum at 20 days of gestation, then fell prior to parturition. In fetuses of diabetic mothers, this prepartum decline was curtailed, resulting in enhanced synthase a activity and increased glycogen content in fetal livers at term. Elevation in hepatic synthase a in fetuses of diabetic mothers was due, not to altered interconversion between existing synthase a and b, but to equivalent increases in both forms of the enzyme. Both hepatic and free plasma corticosterone levels were elevated in fetuses of diabetic mothers and may be responsible for the enhanced development of total glycogen synthase observed in these fetuses. In normal fetuses hepatic phosphofructokinase and pyruvate kinase activities also rose to maxima at 20 days, then declined prior to term. In fetuses of diabetic mothers pyruvate kinase activity attained higher than normal maximal levels and phosphofructokinase activity fell more gradually, thus resulting in elevations in both enzyme activities at term. Augmentations in these glycolytic enzymes are compatible with hyperinsulinemia observed in fetuses of diabetic mothers. The following conclusions may be drawn from these findings. During late fetal life developmental patterns of rate-limiting hepatic glycogen-synthesizing and glycolytic enzymes are adapted to glucose utilization. In the normal fetus these patterns reverse at term, thereby promoting glucose mobilization, which prepares the fetus for abrupt deprivation of maternal glucose at birth. Maternal diabetes results in retardation of these reversal processes, presumably due to elevations in fetal glucocorticoid and insulin levels. Glycogenolytic and glucogenic capacities are thereby impaired in these fetuses.     

Fetal and postnatal development of cyclic GMP phosphodiesterase activity in the rat brain

Cyclic GMP concentration and cyclic GMP phosphodiesterase activity were studied in rat mothers and fetuses at 17, 19 and 21 days of intrauterine life and 0, 1, 4, 10, 15,20, 30 and 45 days after birth. During this developmental period, the increase in cyclic GMP concentration was discrete and the value in 15-day-old rats was already similar to the adult level. Cyclic GMP phosphodiesterase activity increased from 17- to 19-day fetuses and was significantly reduced in 21-day fetuses, neonates, and 1-day-old rats. This reduction may be a result of fetal endocrine preparation for parturition. During postnatal development, cyclic GMP phosphodiesterase activity increased in a parallel way in the limbic system, corpora striata, cerebral hemispheres, and diencephalon, reaching maximal level between 20 and 30 days after birth, and then decreasing to the adult value. The highest activity was found in corpora striata and the lowest in diencephalon. Cerebellar cyclic GMP phosphodiesterase activity was very high in the 4-day-old rat (257% of adult value) and diminished significantly in the 10-day-old rat with no subsequent changes. Kinetic analysis of the enzyme during postnatal forebrain development showed an increase in both the V_max and the apparent K_m. A decrease in the enzyme's V_max was observed only in the cerebellum.The importance of cyclic GMP phosphodiesterase regulation of cyclic GMP concentrations in the brain during development is discussed.     

超声评分法及肾动脉阻力指数对胎儿肾积水预后的评价价值分析

目的:研究超声评分法及肾动脉阻力指数(RRI)对胎儿肾积水预后的评价价值。方法:将从2016年1月2019年1月经我院超声检查发现的孕晚期肾积水胎儿210例纳入研究,测定其肾实质厚度(RPT)、肾盂前后径(APD)以及肾盂肾盏形态,对上述各项超声检测指标进行评分,累计计算分值。此外,对所有胎儿的积水肾脏肾门部位的RRI值进行测定,并以受试者工作特征(ROC)曲线分析超声评分法与RRI值诊断胎儿肾积水预后类型的价值。结果:所有胎儿出生1年内分别行超声检查以及临床诊断,结果显示210例胎儿,共计420只肾脏,共发生285只肾积水,包括病理性肾积水84只(病理性组),非病理性肾积水201只(非病理性组)。病理性肾积水胎儿超声评分为13分的肾只数占比显著低于非病理性胎儿(P<0.05),而79分的肾只数占比显著高于非病理性胎儿(P<0.05)。病理性肾积水胎儿的平均RRI值为0.74±0.05,显著高于非病理性肾积水胎儿的0.63±0.02,差异有统计学意义(t=26.563,P=0.000)。超声评分法与RRI联合诊断病理性肾积水的曲线下面积(AUC)、敏感度、特异度、准确度均显著高于超声评分法或RRI单独诊断(P<0.05)。结论:超声评分法及RRI诊断对胎儿肾积水预后评价具有较重要的价值,值得临床推广应用。     

Activities of enzymes of phospholipid and fatty acid synthesis in fetal and adult rat type II pneumocytes

Although differentiated fetal and adult type II pneumocytes are ultrastructurally similar, it is not known whether there are metabolic differences between them. We measured the activities of selected enzymes of phospholipid and fatty acid synthesis in fetal and adult rat type II cells, in late gestation fetal rat lung explants and in intact lung from rat fetuses of comparable gestational age. The activity of 1-acylglycerophosphocholine acyltransferase was significantly greater in adult type II cells than in fetal type II cells, fetal explants or intact fetal lung. The activity of CDP diacylglycerol:glycerol-3-phosphate 3-phosphatidyltransferase was similar in fetal and adult type II cells, but significantly lower in explants and intact fetal lung. There was a significant positive correlation between the percentage of alveolar epithelial cells in the cultures and tissue studied and CDP diacylglycerol:glycerol-3-phosphate 3-phosphatidyltransferase activity. This suggests that the previously reported correlation between phosphatidylglycerol synthesis and the percentage of alveolar epithelial cells in various lung culture systems may be related to the activity of this enzyme. Phosphatidylglycerol synthesis and CDP diacylglycerol:glycerol-3-phosphate 3-phosphatidyltransferase activity may be metabolic markers of type II cells, whereas the acyltransferase activity may be an indicator of type II cell maturation.     

Retardation of fetal brain cell growth during maternal starvation: Circulating factors versus altered cellular response

Maternal starvation inhibits fetal brain development during late gestation in the rat. To determine whether intrinsic or extrinsic factors might be the principal contributor to altered growth, brain cells from 20 day fetuses were cultured in a 96 well plate with MEM and 10% adult rat serum. Tissue growth was monitored by spectrophotometric measurement of the mitochondrial reduction of a chromagen 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT). After 1, 4 or 6 days incubation, MTT activity in non confluent cultures was shown to be directly related to tissue mass. When fetal brain cell cultures were incubated with 1% and 10% concentrations of adult rat serum, an 11-fold increase in MTT activity paralleled a 15-fold increase in tritiated thymidine incorporation. The impact of maternal starvation on fetal brain cell growth was examined by measuring MTT activity in fetal brain cells from fed and starved mothers. When cultures were incubated for 6 days with graded concentrations of fed adult serum (1.25–10%), the MTT response was slightly but consistently lower in cells from starved when compared with cells from fed mothers. By contrast, a marked difference in MTT activity which was paralleled by a lower DNA content became apparent when fetal rat brain cells were incubated with starved adult serum. Fetal serum and adult male serum were found to support growth equally well, while incubation of fetal brain cells with maternal sera resulted in lower MIT values than with the corresponding fetal sera. When cells were incubated with fetal sera pooled from starved mothers, MTT activity was decreased by 42 to 45%. A relative decrease in MTT activity was also apparent when cells were exposed to sera from starved mothers. Graded concentrations of starved fetal serum (2.5–10%) produced an increase in MTT activity that was consistently lower than similar concentrations of fed fetal serum, a finding suggesting a decrease in growth factors. Mixing fasted with fed serum did not correct the diminished growth, and indicated that an inhibitor might also be functioning to restrict growth. These findings therefore suggest that the principal determinants of diminished fetal brain growth during maternal starvation are not only intrinsic to the cells but are importantly related to the altered extrinsic factors in the fetal circulation.     

The appearance, properties, and functions of gluconeogenic enzymes in the liver and kidney of the guinea pig during fetal and early neonatal development.

The changes in the activity and properties of the four gluconeogenic enzymes have been followed during development of the guinea pig. Pyruvate carboxylase was almost exclusively mitochondrial and kinetically identical to the adult liver enzyme and did not appear in significant activity until after day 50 when it rose to values several times higher than those in the adult liver, then fell after birth. Little activity was detected in the fetal kidney. Phosphoenolpyruvate carboxylase appeared in the fetal liver from day 30 on, both in the mitochondrial and cytoplasmic fractions. The cytoplasmic enzyme was kinetically and chromatographically identical to the mitochondrial enzyme of the fetal and maternal liver. After birth the activity of the cytoplasmic enzyme increased and that of the particulate enzyme fell. Fetal kidney activity appeared several days before birth. Fructose 1,6-diphosphatase and glucose 6-phosphatase appeared in the fetal liver and kidney after day 40; the former showed no postnatal change while the latter rose 10-fold after birth. Fetal liver fructose 1,6-diphosphatase was more sensitive to AMP and fructose 1,6-diphosphate inhibition but was chromatographically indistinguishable from the maternal liver enzyme. Despite the presence of the gluconeogenic enzymes, gluconeogenesis and glyconeogenesis were not detected in the fetal liver until 7–9 days before birth. While the synthesis of glyceride-glycerol from 3-carbon compounds was detected from 35–40 days onwards and some of the gluconeogenic enzymes participate in that pathway, gluconeogenesis was not detected in the fetal kidney.     

Adrenal growth and ontogeny of adrenal substance P, enkephalins and catecholamines in the ovine fetus

Biologically active peptides have been identified in the adrenal glands of several adult mammalian species. Some of these peptides appear to modulate the nicotine-induced catecholamine release from the adrenal medulla. The present study was carried out to investigate the presence and ontogeny of the peptides substance P, met-enkephalin and leu-enkephalin in the ovine fetal adrenal gland from 70 to 140 days gestation (term = 145-150 days). Concurrently, the growth of the fetal adrenal as well as the gestational changes in catecholamine content were determined. The maternal adrenal glands were also studied for comparison. The ovine fetal adrenal gland increased in weight with advancing gestation at a single exponential rate. Total adrenal substance P content correlated with gestational age, while met-enkephalin, leu-enkephalin and total catecholamine contents correlated with adrenal weight. The adrenal content (normalized as per unit protein) of substance P was highest in the young fetuses at 70 days gestation, decreased progressively towards term and, in the adult levels were significantly lower than those measured in the fetuses. The contents of met-enkephalin and leu-enkephalin were low in the young fetuses at 70 days gestation, but reached high levels at 130 to 140 days gestation. Maternal adrenal contents of the two enkephalins were significantly lower than those measured in the near-term fetal adrenal. Total catecholamine content in the fetal adrenal medulla increased as the fetus matured. Norpinephrine was the primary catecholamine present in the medulla of fetuses at 70 and 80 days gestation, while epinephrine was the major one in the adult.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biochemical and Molecular Responses to Loss of Renal Mass: Atpase and Cyclic Nucleotides: Evidence for Altered Cyclic Nucleotide Metabolism During Compensatory Renal Hypertrophy and Neonatal Kidney Growth

In adult male Sprague-Dawley rats contralateral nephrectomy was followed by an initial fall of the concentration of cGMP in renal cortical tissue followed by a rise to a peak level of 300 percent of the initial concentration within two hours. cGMP concentration in the remaining renal cortex remained at about 300 percent of the initial value during the subsequent 72 hours and slowly declined to 150-200 percent in the following two weeks. The changes in cGMP concentration were due to exactly parallel changes in the soluble fraction of renal cortical guanylate cyclase activity, while cGMP-phosphodiesterase activity remained unchanged. cAMP concentration after contralateral nephrectomy fell significantly by about 25 percent within two hours and remained below baseline level for up to eight hours. In the kidneys of newborn rats the concentration of cAMP was approximately one-half that found in adult kidneys: it slightly fell between the fourth and the seventh day after birth and subsequently continuously rose to reach adult values approximately two weeks after birth. The concentration of cGMP was significantly greater four days after birth than in adult rats, further rose between the fourth and the seventh day after birth and subsequently gradually declined to adult levels. The increased cGMP concentration appears to be due to an increase of guanylate cyclase activity in total kidney homogenates which, in turn, was mainly due to an increase of the particulate (membrane-bound) fraction of the enzyme. cGMP-phosphodiesterase activity, however, was also increased in respect to adult levels, one or three weeks after birth. Renal growth from the seventh day after birth to adulthood is accompanied by a continuous increase of the ratio cAMP/cGMP. Removal of one kidney four to seven days after birth resulted in a slower increase of this ratio. The data suggest that cGMP may trigger renal growth and that increases of cGMP concentration in the kidneys are the result of a primary increase in the activity of guanylate cyclase.