RELATIONSHIP BETWEEN FOETAL CORTICOSTEROIDS, MATERNAL PROGESTERONE AND PARTURITION IN THE RAT

1977 ◽  
Vol 84 (1) ◽  
pp. 167-176 ◽  
Author(s):  
C. E. Martin ◽  
M. H. Cake ◽  
P. E. Hartmann ◽  
I. F. Cook
Keyword(s):  
Body Weight ◽  
Protein Binding ◽  
Binding Assay ◽  
Maternal Plasma ◽  
Adrenal Weight ◽  
Significant Fall ◽  
Protein Binding Assay ◽  
Corticosteroid Binding Globulin ◽  
Unit Body Weight ◽  
Low Levels

ABSTRACT The concentration of total corticosteroids, corticosteroid binding globulin (CBG) and progesterone were determined in maternal and foetal/neonatal plasma from rats on days 5, 4, 3, 2, 1 before birth and days 0, 1, and 4 after birth. In addition free corticosteroids and adrenal weight/unit body weight were measured on the foetuses/neonates and the foetuses, respectively. Although the concentration of maternal total corticosteroids and CBG ranged from 53.0 ± 12.5 to 31.0 ± 13.1 μg/100 ml (x̄ ± sem) and 26.6 ± 2.2 to 45.1 ± 0.9 μg corticosteroid bound/100 ml plasma, respectively, the changes in the concentration of these constituents were not related to the initiation of either parturition or lactation. The concentration of total corticosteroids in foetal plasma increased significanly (P < 0.05) from day 5 (14.6 μg/100 ml) to reach peak concentrations (44.9 μg/100 ml) on day 3 before birth and then decreased to low levels (7.7 μg/100 ml) at birth. The pattern of change in foetal adrenal weight/unit body weight closely followed the pattern of change in the concentration of total corticosteroids in foetal plasma during the last 5 days of gestation. There was a significant (P < 0.05) daily decrease in the concentration of CBG in the foetuses from 4 days before until 1 day before birth, which resulted in a significant (P < 0.01) increase from 3.08 to 5.94 μg/100 ml of free corticosteroids in the foetal plasma between day 2 and day 1 before birth, respectively. This peak corresponded with a significant fall (P < 0.02) in the maternal progesterone (measured by protein binding assay) from 2.57 μg/100 ml to 0.62 μg/100 ml between day 2 and day 1 before birth. Foetal progesterone (measured by radioimmunoassay) showed the same changes as maternal progesterone but was between 25–50 % of that in maternal plasma. These findings suggest that the changes in foetal free corticosteroids and maternal progesterone are important in the initiation of parturition in the rat.

A Simplified competitive protein-binding assay for 25-hydroxycalciferol

1976 ◽  
Vol 68 (2) ◽  
pp. 99-105 ◽  
Author(s):  
B. Garcia-Pascual ◽  
A. Peytremann ◽  
B. Courvoisier ◽  
D.E.M. Lawson
Keyword(s):  
Protein Binding ◽  
Binding Assay ◽  
Protein Binding Assay ◽  
Competitive Protein Binding Assay ◽  
Competitive Protein Binding

24,25-dihydroxyvitamin D3 in serum: sample purification with Sep-Pak C-18 cartridges and liquid chromatography before protein-binding assay.

1983 ◽  
Vol 29 (10) ◽  
pp. 1806-1807 ◽  
Author(s):  
M L Traba ◽  
M Babé ◽  
C de la Piedra ◽  
A Marín
Keyword(s):  
Liquid Chromatography ◽  
Protein Binding ◽  
Serum Sample ◽  
High Performance ◽  
Binding Assay ◽  
Reversed Phase ◽  
Specific Method ◽  
Dihydroxyvitamin D3 ◽  
Protein Binding Assay ◽  
24,25 Dihydroxyvitamin D3

Abstract We describe a precise, specific method for measuring 24,25-dihydroxyvitamin D3 in human serum. A 2-mL serum sample is extracted with acetonitrile and passed through a Sep-Pak C-18 cartridge. The sample is further purified by "high-performance" liquid chromatography under isocratic conditions on a normal-phase column (Radial-Pak silica-gel cartridge), then subjected to a protein-binding assay. The mean concentration of 24,25-dihydroxyvitamin D3 in serum from 22 normal adults (measured during the spring) was 2.9 micrograms/L (SD 1.9, range 6.3-0.42 microgram/L). The intra-assay CV was 7.7%, the interassay CV 11.2%. Purification of the sample with Sep-Pak C-18 and liquid chromatography on normal plus reversed-phase columns leads to a mean value of 3.4 micrograms/L (SD 1.6 micrograms/L, n = 12), not significantly different from results with our method.

A Competitive Protein-Binding Assay for 25-Hydroxycholecalciferol

1975 ◽  
Vol 17 (2) ◽  
pp. 57-57
Author(s):  
Yoshiki Seino ◽  
Tsunesuke Shimotsuji ◽  
Shintaro Okada ◽  
Teisuke Hiejima ◽  
Chiiko Ikehara ◽  
...  
Keyword(s):  
Protein Binding ◽  
Binding Assay ◽  
Protein Binding Assay ◽  
Competitive Protein Binding Assay ◽  
Competitive Protein Binding ◽  
25 Hydroxycholecalciferol

An improved protein binding assay for cyclic AMP

1974 ◽  
Vol 58 (2) ◽  
pp. 459-468 ◽  
Author(s):  
Charles O. Brostrom ◽  
Christine Kon
Keyword(s):  
Cyclic Amp ◽  
Protein Binding ◽  
Binding Assay ◽  
Protein Binding Assay

Lesions of hypothalamic paraventricular nuclei do not prevent the effect of estradiol on energy and fat balance

1994 ◽  
Vol 267 (1) ◽  
pp. E32-E38 ◽  
Author(s):  
A. Dagnault ◽  
D. Richard
Keyword(s):  
Body Weight ◽  
Adrenocorticotropic Hormone ◽  
Binding Assay ◽  
Placebo Treatment ◽  
The Body ◽  
Ovariectomized Rats ◽  
Paraventricular Nuclei ◽  
Chronic Effects ◽  
Protein Binding Assay ◽  
Hypothalamic Paraventricular Nuclei

The chronic effects of estradiol (E2) on energy balance have been investigated in ovariectomized rats with hypothalamic paraventricular nuclei (PVH) lesions. Body weight and food intake were monitored throughout the E2 treatment, which lasted 26 days. At the end of this treatment, rats were decapitated, and their carcasses were processed to determine the body contents in energy, fat, and protein. Plasma adrenocorticotropic hormone (ACTH) and corticosterone were determined by radioimmunoassay and protein-binding assay at the end of the study. Regardless of whether they were sham- or PVH-lesioned, E2-treated rats ate, expended, and gained significantly less energy than untreated animals. In addition, E2-treated rats deposited less fat and protein than the rats not receiving E2. In contrast to the E2 treatment, PVH lesions accelerated the gains in energy and fat regardless of whether the rats were treated with E2 or with a placebo. There were no interaction effects of PVH lesions and the E2 treatment on energy or fat gains. Plasma levels of corticosterone and ACTH were higher in E2-treated rats than in animals receiving the placebo treatment. The present results provide evidence that the hypothalamic PVH is not an essential neuroanatomical structure in the effects of E2 on energy and fat balances.

THYROID FUNCTION IN THE FOETAL LAMB DURING THE LAST THIRD OF GESTATION

1973 ◽  
Vol 58 (3) ◽  
pp. 535-546 ◽  
Author(s):  
P. W. NATHANIELSZ ◽  
R. S. COMLINE ◽  
MARIAN SILVER ◽  
A. L. THOMAS
Keyword(s):  
Body Weight ◽  
Thyroid Function ◽  
Maternal Plasma ◽  
Maternal Circulation ◽  
Foetal Circulation ◽  
Unit Body Weight ◽  
Intravascular Catheters ◽  
Pregnant Ewe ◽  
Foetal Lamb

SUMMARY Foetal plasma thyroxine levels as well as thyroxine turnover and placental permeability to this hormone were investigated in the conscious pregnant ewe with foetal and maternal intravascular catheters. Foetal plasma thyroxine levels ranged from 4·6 to 6·2 μg/100 ml between 103 days of gestation and the day of birth. Maternal plasma thyroxine levels varied between 2·3 and 4·1 μg/100 ml over the same period. The maternal: foetal ratio across the placenta for thyroxine varied from 0·52 to 0·65. Distribution of radioactive thyroxine injected into the foetal or maternal circulation demonstrated the impermeability of the placenta to thyroxine. Maternal to foetal ratios for labelled thyroxine were 6·2 to 11·9 when injected into the maternal circulation and 0·013 to 0·003 when injected into the foetal circulation. The sheep placenta appears to be capable of actively transporting iodide to maintain a foetal to maternal iodide ratio of up to 8:1. Foetal thyroxine utilization was of the same order at 111 days of gestation as immediately before parturition when expressed per unit body weight. Utilization of thyroxine per kg by the foetus was about five times that of the mother. Various factors which influence thyroid function are discussed and the activity of the foetal pituitary—thyroid system is compared with other foetal endocrine systems.

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