Fetal Rabbit Tissues Research Articles

Leptin Gene Expression in Rabbits During Pregnancy and Fetal Life

Leptin may act as the critical link between adipose tissue and reproduction. Although considerable progress has been achieved in understanding the reproductive actions of leptin, much work is needed for understanding its physiological role. Till now, no data has been published about the distribution and expression levels of leptin in the rabbit maternal adipose tissue, placenta, and various fetal rabbit tissues during pregnancy and postpartum. Our results indicated that circulating leptin levels in rabbit serum during pregnancy were significantly higher than in postpartum and non pregnant rabbits. Furthermore, leptin showed positive correlations with body weight and estrogen and negative correlation with progesterone in pregnant and postpartum rabbits. RT-PCR verified the presence of RNAs encoding leptin in the rabbit maternal perirenal adipose tissue, placenta, and several fetal tissues; including brain, liver, adipose tissue, and bone. The relative abundance of leptin RNA in rabbit maternal adipose was significantly higher at 20 th day of pregnancy than that of non pregnant rabbits, while it was significantly decreased at 2 nd day after parturition. No significant changes in the placental leptin RNA levels were noticed in pregnant rabbits at 10 th , 20 th , and 30 th day of pregnancy. The relative abundance of fetal leptin transcripts at day 30 th of pregnancy was in the order of liver> bone ? adipose tissue > brain. The present study provides new evidence for the distribution and expression levels of leptin in the rabbit maternal and fetal tissues during pregnancy and supports the importance of leptin in reproductive physiology and fetal development.

Leptin Gene Expression in Rabbits during Pregnancy And Fetal Life

Leptin may act as the critical link between adipose tissue and reproduction.Although considerable progress has been achieved in understanding the reproductive actions of leptin, much work is needed for understanding its physiological role. Till now, no data has been published about the distribution and expression levels of leptin in the rabbit maternal adipose tissue, placenta, and various fetal rabbit tissues during pregnancy and postpartum. Our results indicated that circulating leptin levels in rabbit serum during pregnancy were significantly higher than that in postpartum and non pregnant rabbits. Furthermore, leptin showed positive correlations with body weight in pregnant and postpartum rabbits. RT-PCR verified the presence of RNAs encoding leptin in the rabbit maternal perirenal adipose tissue, placenta, and several fetal tissues; including brain, liver, adipose tissue, and bone. The relative abundance of leptin RNA in rabbit maternal adipose tissue was significantly higher at 20th day of pregnancy than that of non pregnant rabbits, while it was significantly decreased at 2nd day after parturition. No significant changes in the placental leptin RNA levels were noticed in pregnant rabbits at 10th, 20th, and 30th day of pregnancy. The relative abundance of fetal leptin transcripts at day 30th of pregnancy was in the order of liver> bone ≥ adipose tissue > brain. The present study provides new evidence for the distribution and expression levels of leptin in the rabbit maternal and fetal tissues during pregnancy and supports the importance of leptin in reproductive physiology and fetal development.

Fluorescent Microscopic Study of Epithalon Binding in Maternal and Fetal Rabbit Tissues in Health and under Conditions of Placental Insufficiency

Epithalon (regulatory tetrapeptide) labeled with dansil (fluorescent stain) easily penetrates into all tissues and organs of pregnant rabbit females and through the placenta into fetal organs. Incorporation of labeled epithalon in placental tissues is more often observed in fetuses developing under conditions of placental insufficiency than in normal fetuses.

Rapid characterization of cellular retinoid-binding proteins by high-performance size-exclusion chromatography

A high-performance size-exclusion chromatographic method was developed for the analysis of cellular retinol and retinoic acid-binding proteins. The chromatographic analysis of the retinol-retinol-binding protein complex or the retinoic acid-retinoic acid-binding protein complex requires 15 min. The use of high-specific-radioactivity retinoid ligand (30–40 Ci/mmol) allows routine detection of 25 fmol of retinoid-binding protein/mg of cytosolic protein. Thus, this method provides a rapid alternative to sucrose density gradient sedimentation analysis of the cellular retinoid-binding proteins. High-performance size-exclusion chromatography is well suited to screening novel tissues, tumors, and cell lines for the presence of retinoid-binding proteins and to the further characterization of these cellular proteins. This method was applied to the characterization of cellular retinol- and retinoic acid-binding proteins in fetal rabbit tissues. Both retinol- and retinoic acid-binding proteins were detected in fetal rabbit brain, intestine, kidney, and lung at a gestational age of 28 days. Neither retinoidbinding protein was detected in 28-day-old fetal rabbit placenta. Specific retinoic acid binding in fetal intestinal cytosol decreased as a function of increasing gestational age.

Cyclic nucleotide phosphodiesterase and protein activator in fetal rabbit tissues

Cyclic nucleotide phosphodiesterase activity (EC 3.1.4.17) was studied in fetal and newborn rabbit brain, heart, liver, kidney, and lung. Kinetic analysis of phosphodiesterase activity from homogenates of organs from the 25-day embryo suggested the presence of a high K m and a low K m activity for both cyclic AMP and cyclic GMP hydrolysis. The addition of 1 μ m cyclic GMP to the assay stimulated the hydrolysis of cyclic AMP by whole homogenates of liver, brain, lung, and kidney, but not heart, at all of the ages studied. The addition of micromolar levels of calcium ion stimulated cyclic GMP hydrolysis by homogenates of fetal brain, heart, and kidney, with or without added protein activator. Cyclic GMP phosphodiesterase activity was not stimulated by the addition of calcium ion in homogenates of early fetal rabbit liver and lung, but stimulation was detected in the late embryo and newborn. The presence of the heat-stable protein activator was demonstrated in brain, heart, kidney, liver, and lung tissue at all of the fetal ages studied, and in the newborn rabbit. DEAE-cellulose chromatography demonstrated the presence of three separable enzymes in brain and liver at 15 days, heart at 19 days, and lung and kidney at 25 days of gestation, with no changes in the kinetic properties of the isolated enzymes during development. These experiments suggest that all of the organs studied have the mature array of phosphodiesterases early in development, but an enzyme from liver and lung becomes sensitive to regulatory control by calcium only late in gestation.

Uptake and metabolism of 14C-palmitate by fetal rabbit tissues.

The uptake and esterification of 14C-palmitate into lipid classes in placenta, fetal brown adipose tissue (BAT) and liver of rabbits were investigated in vitro. Fetal BAT showed a high rate of fatty acid uptake, 8.5 mumol-a-1 tissue-h-1. From 5 min onwards, the majority of incorporated label was in the triglyceride fraction. The placenta and fetal liver also incorporated I-[14C]-palmitate into both FFA and esterified lipid fractions, although at much lower rates than observed for BAT. In the liver, triglycerides, but in the placenta phospholipids, contained the majority of the label after 1 h incubation. BAT from both fetal and newborn rabbits released 14CO2 and the production of 14 CO2 was greater in the presence of noradrenaline. The specific activity of the CO2 was the same in stimulated and unstimulated tissue. It is concluded that BAT as well as the liver are important sites of free fatty acid removal from the fetal circulation. The potential for fatty acid oxidation is present in BAT of the 28-day rabbit fetus.

General presence of glucocorticoid receptors in mammalian tissues.

The adrenal glucocorticoids are almost ubiquitous as physiologic regulators in mammalian tissues. The present experiments show that specific cytoplasmic “receptors” for glucocorticoids are present in most tissues of the juvenile rat and rabbit which respond to these hormones. These findings suggest that most physiologic effects of glucocorticoids are mediated through these receptors. A few tissues such as prostate, uterus, and seminal vesicle lack the receptor and thus may not be direct “targets” for glucocorticoids. Receptor levels in juvenile and fetal rabbit tissues are generally similar. However, with rabbit thymus and rat lung there are marked changes during development, suggesting that in some cases developmental changes in receptor levels may determine hormone responsiveness. (Endocrinology 94: 998, 1974)

Comparison of 95Zr and 95Nb Distributions in Maternal and Fetal Rabbit Tissues.

The fission products 95Zr and 95Nb form a radioactive “parent-daughter” pair whose metabolic behavior in animals and man is of interest because of their appearance in the environment following the detonation of nuclear devices. Peaks in the concentrations of 95Zr-95Nb on airborne particles were observed during early 1962 and 1963(1), and these nuclides have been identified in food(2) and humans (3,4). The early work of Hamilton and associates (5) and others (6,7) has shown that small but measurable amounts of 95Zr-95Nb can enter the mammalian body via ingestion and inhalation. 95Zr and 95Nb both emit gamma rays, but their energies (0.72–0.76 Mev) are so similar that it is impractical to assay the amounts of each nuclide in a mixture by γ-scintillation spectrometry. This has made it difficult to compare the metabolic behavior of the parent 95Zr to that of the daughter 95Nb, in the carrier-free condition. Sastry et al(8) approached this problem by determining the effective physical half life of γ-activity i...