scholarly journals Oxytocin and vasopressin have no effect on progesterone production and cyclic AMP accumulation by rat luteal cells in vitro

Reproduction ◽  
1984 ◽  
Vol 72 (1) ◽  
pp. 137-141 ◽  
Author(s):  
A. K. Mukhopadhyay ◽  
A. Kumar ◽  
R. Tams ◽  
H. G. Bohnet ◽  
F. A. Leidenberger
Keyword(s):  
Cyclic Amp ◽  
Luteal Cells ◽  
Progesterone Production ◽  
Cyclic Amp Accumulation

The autonomy of the rabbit corpus luteum

1994 ◽  
Vol 143 (3) ◽  
pp. 423-431 ◽  
Author(s):  
P L Keyes ◽  
J L Kostyo ◽  
R Towns
Keyword(s):  
Cyclic Amp ◽  
Adenylyl Cyclase ◽  
Corpus Luteum ◽  
High Rate ◽  
Cyclase Activity ◽  
Corpora Lutea ◽  
Adenylyl Cyclase Activity ◽  
Luteal Cells ◽  
Progesterone Production

Abstract The rabbit corpus luteum possesses LH receptors that are coupled to adenylyl cyclase, but paradoxically it does not require LH as a luteotrophic factor for the maintenance of progesterone secretion. This suggests that rabbit luteal cells may not respond physiologically to LH. Therefore, the present study was undertaken to investigate the responsiveness of the rabbit corpus luteum of pseudopregnancy to human chorionic gonadotrophin (hCG) which acts on the same receptor as LH. Pseudopregnancy was induced by injection of 40 IU pregnant mare serum gonadotrophin followed 50 h later by an injection of 40 IU hCG (day 0). On days 7 and 11 of pseudopregnancy, corpora lutea were obtained and incubated for 2 or 5 h in the presence of either 0·1 or 1 μg/ml hCG or 1 mm monobutyryl cyclic AMP (bcAMP). Neither hCG nor bcAMP stimulated progesterone production by the isolated corpus luteum, despite a sustained high rate of progesterone production by the tissue throughout the incubation period. By contrast, Graafian follicles removed from the same ovaries and incubated under the same conditions responded both to hCG and bcAMP with large increases in progesterone production. To determine whether the cyclic AMP content of the corpus luteum was altered by in vitro exposure to hCG, day 7 and day 11 corpora lutea were incubated for 5 or 15 min with various concentrations of hCG, and cyclic AMP in the tissue was then measured. Even at the highest concentration of hCG tested (10 μg/ml), the cyclic AMP content of the corpus luteum was unaltered. Given this result, the acute effects of various concentrations of hCG on the adenylyl cyclase activity of homogenates of day 11 corpora lutea were examined. Consistent with previous reports of others, adenylyl cyclase activity was stimulated, but only at a high concentration of hCG (1 μg/ml), and the degree of stimulation of the enzyme (∼75%) was quite modest. By contrast, the adenylyl cyclase activity of homogenates of rabbit Graafian follicles was stimulated by even the lowest concentration of hCG tested (0·01 μg/ml). Thus, the adenylyl cyclase of the rabbit follicle is much more sensitive to hCG stimulation than the luteal form of the enzyme. Given the poor responsiveness of luteal adenylyl cyclase to hCG, the possibility was considered that cyclic AMP production in response to hCG might be obscured by luteal cell phosphodiesterase. When day 11 corpora lutea were incubated with hCG in the presence of the phosphodiesterase inhibitor, isobutyl methylxanthine (5 mm), there was a marked increase in the cyclic AMP content of the tissue. Despite this large increase in endogenous cyclic AMP, progesterone production by the corpora lutea was again unaffected. Thus, the rabbit corpus luteum is insensitive to stimulation in at least two major respects. The adenylyl cyclase coupled to the LH receptor is resistant to stimulation by LH (hCG), and steroidogenesis, as reflected by progesterone production in vitro, is not stimulated acutely by cyclic AMP. These results suggest that progesterone biosynthesis in the rabbit corpus luteum is not a regulated process, but rather a process that becomes autonomous as a result of the differentiation of granulosa cells into luteal cells. Therefore, the role of a luteotrophin, such as oestrogen in the rabbit, is to maintain the health and viability of the luteal cells, which have, as an intrinsic property, the capacity to produce progesterone at a high rate. Journal of Endocrinology (1994) 143, 423–431

Vasopressin and oxytocin regulation of cyclic AMP accumulation in rat hypothalamo-neurohypophysial explants in vitro

1990 ◽  
Vol 114 (2) ◽  
pp. 225-230 ◽  
Author(s):  
R.B. Meeker ◽  
K.M. Michels ◽  
J.N. Hayward
Keyword(s):  
Cyclic Amp ◽  
Cyclic Amp Accumulation

scholarly journals Receptor-mediated gonadotropin action in the ovary. Regulatory role of cyclic nucleotide phosphodiesterase(s) in intracellular adenosine 3′:5′-cyclic monophosphate turnover and gonadotropin-stimulated progesterone production by rat ovarian cells

1979 ◽  
Vol 180 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Salman Azhar ◽  
K. M. Jairam Menon
Keyword(s):  
Cyclic Amp ◽  
Kinase Activity ◽  
Phosphodiesterase Inhibitors ◽  
Protein Kinase Activity ◽  
Dibutyryl Cyclic Amp ◽  
Steroid Production ◽  
Progesterone Production ◽  
Ovarian Cells ◽  
Cyclic Amp Accumulation

The regulatory role of cyclic nucleotide phosphodiesterase(s) and cyclic AMP metabolism in relation to progesterone production by gonadotropins has been studied in isolated rat ovarian cells. Low concentrations of choriogonadotropin (0.4–5ng/ml) increased steroid production without any detectable increase in cyclic AMP, when experiments were carried out in the absence of phosphodiesterase inhibitors. The concentration of choriogonadotropin (10ng/ml) that stimulated progesterone synthesis maximally resulted in a minimal increase in cyclic AMP accumulation and choriogonadotropin binding. Choriogonadotropin at a concentration of 10ng/ml and higher, however, significantly stimulated protein kinase activity and reached a maximum between 250 and 1000ng of hormone/ml. Higher concentrations (50–2500ng/ml) of choriogonadotropin caused an increase in endogenous cyclic AMP, and this increase preceded the increase in steroid synthesis. Analysis of dose–response relationships of gonadotropin-stimulated cyclic AMP accumulation, progesterone production and protein kinase activity revealed a correlation between these responses over a wide concentration range when experiments were performed in the presence of 3-isobutyl-1-methylxanthine. The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine each stimulated steroid production in a dose-dependent manner. Incubation of ovarian cells with dibutyryl cyclic AMP or 8-bromo cyclic AMP mimicked the steroidogenic action of gonadotropins and this effect was dependent on both incubation time and nucleotide concentration. Maximum stimulation was obtained with 2mm-dibutyryl cyclic AMP and 8-bromo cyclic AMP, and this increase was close to that produced by a maximally stimulating dose of choriogonadotropin. Other 8-substituted derivatives such as 8-hydroxy cyclic AMP and 8-isopropylthio cyclic AMP, which were less susceptible to phosphodiesterase action, also effectively stimulated steroidogenesis. The uptake and metabolism of cyclic [3H]AMP in ovarian cells was also studied in relation to steroidogenesis. When ovarian cells were incubated for 2h in the presence of increasing concentrations of cyclic [3H]AMP, the radioactivity associated with the cells increased almost linearly up to 250μm-cyclic [3H]AMP concentration in the incubation medium. The 3H label in the cellular extract was recovered mainly in the forms ATP, ADP, AMP, adenosine and inosine, with cyclic AMP accounting for less than 1% of the total tissue radioactivity. Incubation of cyclic AMP in vitro with ovarian cells resulted in a rapid breakdown of the nucleotide in the medium. The degradation products in the medium have been identified as AMP, adenosine and inosine. The rapid degradation of cyclic AMP by phosphodiesterase(s) makes it difficult to correlate changes in cyclic AMP concentrations with steroidogenesis. These observations thus provide an explanation for the previously observed lack of cyclic AMP accumulation under conditions in which low doses of choriogonadotropin stimulated steroidogenesis without any detectable changes in cyclic AMP accumulation.

Characteristics of Action of Prostaglandins on Cyclic AMP Accumulation in Rat Anterior Pituitary Gland

1975 ◽  
Vol 53 (4) ◽  
pp. 455-460 ◽  
Author(s):  
Pierre Borgeat ◽  
Fernand Labrie ◽  
Pierre Garneau
Keyword(s):  
Cyclic Amp ◽  
Pituitary Gland ◽  
Incubation Medium ◽  
Anterior Pituitary ◽  
Complete Removal ◽  
Anterior Pituitary Gland ◽  
Pituitary Hormone ◽  
Maximal Effect ◽  
Cyclic Amp Accumulation

Prostaglandins (PGs) were found to lead to a marked stimulation of cyclic AMP accumulation in rat anterior pituitary gland in vitro in the following decreasing order of potency: [Formula: see text]. The effect of PGs is potentiated by theophylline. The stimulatory effect of PGs on cyclic AMP accumulation is already detected 2 min after the addition of 1 × 10−7 to 1 × 10−6 M PG E2 and its maximal effect is reached after approximately 30 min of incubation, with a progressive decrease toward basal cyclic AMP levels at later time intervals. Increased intracellular cyclic AMP concentrations are accompanied by an increased release of the nucleotide into the incubation medium. Complete removal of Ca2+ from the incubation medium by addition of EGTA was found to increase the stimulatory effect of PG E2 on cyclic AMP accumulation. The action of PGs on hormonal release and cyclic AMP accumulation support the hypothesis of a role of PGs in the mechanism of anterior pituitary hormone (particularly growth hormone) release.

In. vitro evaluation of corpus luteum function of cycling and pregnant rhesus monkeys: Progesterone production by dispersed luteal cells

Steroids ◽  
1976 ◽  
Vol 27 (4) ◽  
pp. 543-551 ◽  
Author(s):  
Richard L. Stouffer ◽  
Wilbert E. Nixon ◽  
Bela J. Gulyas ◽  
David.K. Johnson ◽  
Gary D. Hodgen
Keyword(s):  
Corpus Luteum ◽  
Rhesus Monkeys ◽  
In Vitro Evaluation ◽  
Luteal Cells ◽  
Progesterone Production

CYCLIC AMP AND CYCLIC GMP ACCUMULATION IN HAMSTER PRE-OVULATORY FOLLICLES STIMULATED WITH LH AND FSH

1978 ◽  
Vol 87 (1) ◽  
pp. 158-163 ◽  
Author(s):  
Anastasia Makris ◽  
Kenneth J. Ryan
Keyword(s):  
Cyclic Amp ◽  
Dose Response ◽  
Cyclic Gmp ◽  
Time Course ◽  
Hormone Action ◽  
Acute Response ◽  
Cyclic Amp Accumulation ◽  
Ovulatory Follicles ◽  
Higher Doses

ABSTRACT Cyclic AMP and cyclic GMP accumulation in hamster pre-ovulatory follicles was determined after in vitro stimulation by LH and FSH. Combined time course and dose response experiments determined that the acute response of the follicles (0–30 min) to LH and FSH was similar with respect to cyclic AMP accumulation. The pattern of cyclic GMP accumulation was, however, distinctly different in LH and FSH stimulated follicles. LH increased follicular cyclic GMP only at the lowest dose (0.005 IU/ml), while higher doses of LH had no effect. In contrast, FSH at all doses stimulated cyclic GMP accumulation. The different cyclic AMP to cyclic relationships generated in the follicles by LH and FSH may be determinants in specificity of hormone action in pre-ovulatory follicles.

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