scholarly journals Highly sensitive in vitro bioassay for Luteinizing Hormone and Chorionic Gonadotropin

2021 ◽  
Author(s):  
Danièle Klett ◽  
Yves Combarnous
Keyword(s):  
Cyclic Amp ◽  
Mammalian Species ◽  
Detection Threshold ◽  
In Vitro Bioassay ◽  
Luteinizing Hormones ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
Amplifying Effect ◽  
Luminescence Measurement

IIn previous studies, we had shown the synergistic effect of 10-5 M forskolin (FSK) on the detection threshold of the cyclic AMP response to Luteinizing Hormones (LH) and Chorionic Gonadotropins (CG) from various species in the mouse Leydig Tumor cell (mLTC) cell line. Indepedently, we had started to study the effect of 10-12 – 10-6 M OXT also on the cyclic AMP response to LH and CG preparations on these same cells and found an amplifying effect on the luminescence response caused by gonadotropins. The aim was then to explore the effects of 10-12 – 10-6 M OXT on the gonadotropin-induced cAMP response, in the presence or absence of 10 µM FSK to optimize the assay down to a sensitivity compatible with the detection of the circulating concentrations of these hormones in various species. Finally the optimization relies on three independent phenomena: 1/ the inhibition of nucleotide phosphodiesterase by IBMX to avoid cAMP degradation, 2/ the strong synergy of 10 µM forskolin with low concentrations of LH or CG during the 1-hour luminescence measurement and, 3/ the stimulatory effect of 10-8M oxytocin on the amplitude of transfected cAMP-sensitive luciferase response. By doing this, the detectable concentrations are at the 1-10 pg/well (pM range) for the LHs and CGs from various species. The bioactivities of circulating LHs and CGs in blood or urine are therefore expected to be measurable in 10µL-plasma samples from mammalian species and maybe others.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Regulation of Thromboplastin Synthesis in Mouse Placental Cells In Vitro

1983 ◽  
Vol 50 (04) ◽  
pp. 831-834 ◽  
Author(s):  
Knut Dalaker ◽  
Hans Prydz
Keyword(s):  
Cyclic Amp ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Low Concentrations ◽  
Placental Cells ◽  
Dose Dependent ◽  
Higher Doses ◽  
Dose Dependent Effect ◽  
Methyl Xanthine

SummaryMouse placental cells are probably constitutive producers of the thromboplastin apoprotein in vitro. The effect of cyclic AMP- elevating compounds on their expression of thromboplastin activity has been studied. Dibutyryl cyclic AMP, the phosphodiesterase inhibitor Ro 20-1724 and the adenyl cyclase stimulator forskolin all decrease the synthesis of thromboplastin. Prostaglandin E2 and the phosphodiesterase inhibitor butyl-methyl-xanthine have a biphasic dose dependent effect. A stimulation was observed at low concentrations, whereas higher doses decreased the synthesis of thromboplastin. Adrenaline had no effect. Combination of two compounds, each at maximally inhibiting concentration gave no significant additive inhibitory effect, showing that they probably act via the same pathway.

Accumulation of Adenosine 3′,5′-Monophosphate and Relaxation in the Rat Uterus In Vitro

1971 ◽  
Vol 49 (11) ◽  
pp. 999-1004 ◽  
Author(s):  
Ivo Polacek ◽  
Jean Bolan ◽  
Edwin E. Daniel
Keyword(s):  
Cyclic Amp ◽  
Contractile Activity ◽  
Phosphodiesterase Activity ◽  
Dibutyryl Camp ◽  
Rat Uterus ◽  
Low Concentrations ◽  
Uterine Contractile ◽  
Camp Levels

Theophylline, diazoxide, and papaverine in low concentrations relaxed the uterus with minimal or no elevation of cyclic AMP (cAMP) levels. In higher concentrations, theophylline relaxed the uterus and increased its cAMP levels, but imidazole reversed the increase in cAMP without causing recontraction. Imidazole and NaF caused uterine contractures but did not detectably decrease cAMP levels until several minutes after the onset of contractures. The uterine relaxations produced by theophylline and/or dibutyryl cAMP in amounts which increased uterine cAMP were not reversed by propranolol. These results eliminate the possibility that propranolol interfered with a relaxant action of cAMP. Along with previous data, these results also show that uterine contractile activity was not determined primarily by the general levels of cAMP and that phosphodiesterase activity in the uterus was insufficient to rapidly affect these cAMP levels. Also, substances like theophylline, diazoxide, and papaverine, postulated to inhibit phosphodiesterase activity, did not bring about their relaxant effects by this mechanism.

A phylogenetic study of the role of cyclic AMP in lipid synthesis in vertebrates

1975 ◽  
Vol 229 (1) ◽  
pp. 211-214 ◽  
Author(s):  
LA Bricker ◽  
LA Marraccini
Keyword(s):  
Fatty Acid ◽  
Cyclic Amp ◽  
Mammalian Species ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Sterol Synthesis ◽  
Phylogenetic Study ◽  
Nurse Shark ◽  
Lower Vertebrates

The effect of cyclic AMP on the incorporation of acetate-2-14C into sterols and fatty acid in vitro in slices of liver and intestine was examined in various representatives of the vertebrate group. In no instance was an effect on lipid synthesis noted in intestine. Cyclic AMP exerted no significant effects on hepatic lipogenesis in lower vertebrates, including the nurse shark, catfish, toad, or iguana. However, the nucleotide strongly inhibited the incorporation of acetate-2-14C into fatty acid by the chicken liver. Similar inhibition of fatty acid synthesis was also noted in rat liver, but in this mammalian species hepatic sterol synthesis was also strikingly suppressed by cyclic AMP. Interruption of the enterohepatic circuit in the rat, while enhancing rates of sterol synthesis in both liver and intestine, neither enhanced nor diminished hepatic susceptibility to suppressed sterologenesis by cyclic AMP, nor did it confer on the intestine any newfound capacity for cyclic AMP-regulated lipid synthesis.

Hyperpolarization of thyroid cells in vitro by thyrotropin and cyclic AMP

1976 ◽  
Vol 231 (1) ◽  
pp. 52-55 ◽  
Author(s):  
R Batt ◽  
JM McKenzie
Keyword(s):  
Cyclic Amp ◽  
Short Term ◽  
Thyroid Cells ◽  
Low Concentrations ◽  
Thyroid Glands ◽  
The Relationship ◽  
Effect Of Feeding ◽  
Mouse Thyroid

With the use of microelectrodes, membrane potential (MP) was measured in mouse thyroid glands in vitro. A basal resting MP of about -39 mV was confirmed. The initial effect of feeding a low-iodine diet (6-12 days) was hyperpolarization, up to -47 m V; chronic low-iodine diet led to depolarization. Low concentrations of thyrotropin (less than 3 mU/ml superfusate) caused hyperpolarization and high ones (greater than 10 mU/ml) led to depolarization. Cyclic AMP (10(-3) M), dibutyryl cyclic AMP (1.2 X 10(-4) M or 1.2 X 10(-3) M) and theophylline (10(-2) or 10(-3) M) caused similar hyperpolarization: D- and DL-propranolol (5 X 10(-5) -5 X 10(-4) M) produced depolarization and inhibited hyperpolarization by thyrotropin. Conclusions are that hyperpolarization is a consequence of short-term increased secretion of thyrotropin in vivo or of low (near physiological) concentrations in vitro; these effects are probably mediated by cyclic AMP. The relationship to and mechanism of depolarization resulting from chronic enhanced endogenous secretion or high in vitro concentrations of thyrotropin are unknown.

EFFECT OF MAGNESIUM DEFICIENCY AND PARATHYROID HORMONE ON CYCLIC AMP METABOLISM IN RAT RENAL CORTEX

1975 ◽  
Vol 67 (1) ◽  
pp. 105-112 ◽  
Author(s):  
J. P. ASHBY ◽  
F. W. HEATON
Keyword(s):  
Parathyroid Hormone ◽  
Cyclic Amp ◽  
Renal Cortex ◽  
Magnesium Deficiency ◽  
Standard Dose ◽  
Calcium Content ◽  
Low Calcium ◽  
Low Concentrations ◽  
Basal Concentration

SUMMARY The influence of magnesium deficiency on cyclic AMP metabolism was investigated in rats on diets of normal and low calcium content. Magnesium deficiency itself did not significantly affect either the basal concentration or the parathyroid hormone-stimulated formation of cyclic AMP in the renal cortex. Magnesium-deficient rats with hypercalcaemia excreted more cyclic AMP in the urine, but similar rats that developed hypocalcaemia on low calcium intake excreted less than their respective controls. The former type of animals also tended to accumulate more cyclic AMP in the renal cortex in response to the injection of a standard dose of parathyroid hormone, whereas rats of the latter type accumulated less. The activity of parathyroid hormone-stimulated renal cortical adenylate cyclase in vitro was increased by magnesium and reduced by calcium under most conditions, but with low concentrations of magnesium small amounts of calcium had a stimulatory effect. These observations suggest that cyclic AMP metabolism is influenced by metabolic disorders developing secondary to magnesium deficiency.

EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF MELANOCYTE-STIMULATING HORMONE FROM RAT NEUROINTERMEDIATE LOBES IN VITRO

1974 ◽  
Vol 63 (3) ◽  
pp. 533-538 ◽  
Author(s):  
BRIDGET I. BAKER
Keyword(s):  
Cyclic Amp ◽  
Gel Electrophoresis ◽  
Incubation Medium ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Dibutyryl Cyclic Amp ◽  
Melanocyte Stimulating Hormone ◽  
Low Concentrations ◽  
Stimulating Hormone

SUMMARY A method for measuring melanocyte-stimulating hormone (MSH) in rat neurointermediate lobe in vitro and in incubation medium, using polyacrylamide gel electrophoresis, is described. Using this technique, it was shown that dibutyryl cyclic AMP increased the release of MSH in vitro, the degree of stimulation depending on the concentration of the nucleotide. The effect of low concentrations of the nucleotide was potentiated by theophylline.

Cyclic AMP response to recombinant human relaxin by cultured human endometrial cells—A specific and high throughput in vitro bioassay

1990 ◽  
Vol 170 (1) ◽  
pp. 214-222 ◽  
Author(s):  
David T.W. Fei ◽  
Mary C. Gross ◽  
Julie L. Lofgren ◽  
Marina Mora-Worms ◽  
Anthony B. Chen
Keyword(s):  
Cyclic Amp ◽  
High Throughput ◽  
In Vitro Bioassay ◽  
Endometrial Cells
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