scholarly journals Studies on the role of zinc in parturition in the rat

1983 ◽  
Vol 210 (3) ◽  
pp. 761-767 ◽  
Author(s):  
G E Bunce ◽  
G R Wilson ◽  
C F Mills ◽  
A Klopper
Keyword(s):  
Dehydrogenase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Zn Deficiency ◽  
Progesterone Concentration ◽  
Pregnant Rats ◽  
Plasma Progesterone ◽  
Prostaglandin F2 Alpha

1. Pregnant rats were fed either low (less than 1 p.p.m.) Zn or control (40 p.p.m. Zn) diets from day 10 of gestation. They were killed at intervals during the last 96 h preceding the normal time for onset of parturition, and differences in plasma progesterone, oestradiol-17 beta and ovarian 20 alpha-hydroxysteroid dehydrogenase were assessed. 2. Gestation was prolonged in Zn-deficient rats. 3. Although the preparturient decline in plasma progesterone began at the same time in all groups, at term, plasma progesterone concentration in Zn-deficient rats remained significantly higher than in normal females. 4. Induction of ovarian 20 alpha-hydroxysteroid dehydrogenase activity was delayed by about 8 h by Zn deficiency. This delay was not observed if prostaglandin F2 alpha was injected previously. 5. The results suggest a Zn-dependent step(s) in uterine synthesis and/or release of prostanoids.

scholarly journals Participation of intraluteal progesterone and prostaglandin F2 alpha in LH-induced luteolysis in pregnant rat

1998 ◽  
Vol 156 (2) ◽  
pp. 253-259 ◽  
Author(s):  
CO Stocco ◽  
RP Deis
Keyword(s):  
Corpus Luteum ◽  
Dehydrogenase Activity ◽  
Subcutaneous Administration ◽  
Hydroxysteroid Dehydrogenase ◽  
Good Evidence ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Prostaglandin F2 Alpha

We examined the participation of the intraluteal levels of progesterone (P4) and prostaglandin F2 alpha (PGF2 alpha) in the induction of luteolysis by LH and its relationship with the induction of the 20 alpha-hydroxysteroid dehydrogenase activity (20 alpha-HSD). Subcutaneous administration of four doses of 10 microgram ovine LH (oLH) at 0800, 0900, 1000 and 1100 h on day 19 of pregnancy induced a decrease in the activity of the enzyme 3 beta-HSD 24 and 48 h after treatment and an increase in luteal 20 alpha-HSD activity 48 h after oLH treatment when compared with control rats. Intraluteal and serum P4 levels were lower than control values 24 and 48 h after oLH treatment, with a significant increase in luteal PGF2 alpha content and a decrease in corpus luteum (CL) weight 48 h after oLH treatment. Intrabursal ovarian (i.b.) treatment with an inhibitor of PG's biosynthesis (diclofenac) (70 microgram/ovary) or P4 (3 microgram/ovary) on day 20 of pregnancy, prevented the increase in 20 alpha-HSD activity observed 48 h after oLH treatment, without any effect on 3 beta-HSD activity. The i.b. administration of P4 prevented the increase in intraluteal PGF2 alpha content induced by oLH treatment and the increases in 20 alpha-HSD activity and intraluteal PGF2 alpha content observed in control animals on day 21 of pregnancy. The inhibition of PG biosynthesis also prevents the decrease in intraluteal and serum P4 level induced by oLH. These results provide good evidence of the important participation of intraluteal P4 and PGF2 alpha on the oLH-induced luteolysis in pregnant rats. We also found the P4 produced by the CL is involved, in part, in the regulation of luteal PG synthesis. Thus, the early decline in 3 beta-HSD activity and the consequent fall in intraluteal P4 content, may trigger the synthesis of PGs and thereafter the increase in luteal 20 alpha-HSD activity to establish luteolysis.

Concentrations of cytochrome P450 cholesterol side-chain cleavage enzyme and 3 beta-hydroxysteroid dehydrogenase during prostaglandin F2 alpha-induced luteal regression in cattle

1995 ◽  
Vol 7 (5) ◽  
pp. 1213 ◽  
Author(s):  
RJ Rodgers ◽  
CA Vella ◽  
FM Young ◽  
XC Tian ◽  
JE Fortune
Keyword(s):  
Cytochrome P450 ◽  
Hydroxysteroid Dehydrogenase ◽  
Side Chain ◽  
Corpora Lutea ◽  
Steroidogenic Enzymes ◽  
Rapid Reduction ◽  
Plasma Progesterone ◽  
Side Chain Cleavage ◽  
Prostaglandin F2 Alpha ◽  
Chain Cleavage

Prostaglandin F2 alpha (PGF2 alpha)-induced regression of the corpus luteum causes both plasma progesterone concentrations and luteal concentrations of mRNA encoding the steroidogenic enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) to fall in parallel. To investigate the hypothesis that a decline in the concentrations of mRNA encoding steroidogenic enzymes causes plasma progesterone to fall, the luteal concentrations of the enzymes 3 beta-HSD and cytochrome P450 cholesterol side-chain cleavage were measured during induced luteolysis. Holstein heifers were treated with PGF2 alpha (25 mg Lutalyse) on Day 6 or Day 7 of the oestrous cycle and corpora lutea were collected 0 h, 2 h, 12 h, and 24 h later (n = 6, 4, 4, and 4 respectively). Analyses of the steroidogenic enzymes were carried out by Western immunoblotting. The luteal concentrations of both steroidogenic enzymes did not decrease over the 24-h period. It is concluded that, although the concentrations of mRNA encoding steroidogenic enzymes may decline in response to PGF2 alpha, this does not lead to a sufficiently rapid reduction in the concentrations of the enzymes to precede, and thus cause, the decline in plasma progesterone concentrations. Thus, the mechanism for the initial decline in plasma progesterone concentrations during luteolysis is still not known.

Attenuation of preovulatory gonadotrophin surges by epostane: a new inhibitor of 3β-hydroxysteroid dehydrogenase

1988 ◽  
Vol 118 (1) ◽  
pp. 59-68 ◽  
Author(s):  
L. V. DePaolo
Keyword(s):  
Peak Plasma ◽  
Plasma Concentrations ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effects ◽  
Plasma Progesterone ◽  
Ru 486 ◽  
Progesterone Secretion ◽  
Progesterone Antagonist

ABSTRACT Epostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, was administered orally to pro-oestrous rats to evaluate further a possible role for preovulatory progesterone secretion in eliciting surges of LH and FSH. Whereas a dose of 10 mg epostane/kg had essentially no effects on preovulatory gonadotrophin surges and ovulation, 200 mg epostane/kg markedly attenuated LH and FSH surges and blocked ovulation. A dose of 50 mg epostane/kg exerted effects on LH and FSH surges and ovulation intermediate between those of doses of 10 and 200 mg/kg. Plasma concentrations of progesterone were significantly lower in all anovulatory epostane-treated rats at 18.00 and 22.00 h on pro-oestrus than those measured in vehicle-treated rats. Concurrent injection of 2 mg progesterone in rats given 200 mg epostane/kg restored gonadotrophin surges to normal, but consistently failed to reverse the inhibitory effects of epostane on ovulation. Peak plasma progesterone levels produced by the progesterone injections were eight- to tenfold higher than the highest levels measured in vehicle-treated rats during the afternoon of pro-oestrus. Insertion of progesterone capsules was less effective than injections of progesterone in restoring gonadotrophin surges to normal, even though peak plasma progesterone concentrations achieved after insertion of two 20 mm long progesterone capsules were double the peak progesterone concentrations measured in control rats. Nevertheless, taken together with recent reports showing attenuation of preovulatory gonadotrophin surges by the progesterone antagonist RU 486 (17β-hydroxy-11β-[4-dimethyl-aminophenyl]-17α-[prop-1-ynl]estra-4,9-diene-3-one), the present results provide support for a role of preovulatory progesterone secretion in enhancing oestrogen-dependent LH/FSH surges on pro-oestrus. J. Endocr. (1988) 118, 59–68

Inhibition of progesterone secretion by a 3β-hydroxysteroid dehydrogenase inhibitor in late pregnant sheep

1985 ◽  
Vol 63 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Graham Jenkin ◽  
Geoffrey D. Thorburn
Keyword(s):  
Hydroxysteroid Dehydrogenase ◽  
Placental Lactogen ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
Pregnant Sheep ◽  
Plasma Estradiol ◽  
Prostaglandin F ◽  
Essential Prerequisite ◽  
Estradiol 17Β

The role of progesterone in the initiation of parturition in the sheep is unclear. Whether a decrease in plasma progesterone is the essential prerequisite for the initiation of parturition or whether other factors also maintain uterine quiescence until delivery is not known. The effect of withdrawal of progesterone on the initiation of parturition has been investigated by intravenous administration of trilostane, a 3β-hydroxysteroid dehydrogenase Δ5−4 isomerase inhibitor, to late pregnant sheep. Twenty-five or 100 mg trilostane caused a precipitous decrease in plasma progesterone to about 30% of preinjection levels. Progesterone remained depressed for up to 7 days after treatment. 13,14-Dihydro-15-keto-prostaglandin F2α (PGFM) became elevated between 7 and 36 h after trilostane injection but gradually returned to preinjection levels during the subsequent 36 h, at a time when plasma progesterone was still depressed. Four of 11 animals treated with 100 or 200 mg trilostane aborted prematurely at a time when plasma PGFM was maximal and plasma progesterone minimal. There were no consistent changes in plasma estradiol-17β or ovine placental lactogen concentrations after treatment with trilostane. It is suggested that a decrease in plasma progesterone will cause a transient increase in plasma PGFM concentrations which can lead to the premature initiation of parturition. In some instances the myometrium does not appear to respond to the elevated PGFM concentrations even when the estrogen:progesterone ratio is elevated by a decrease in plasma progesterone.

Pressor responsiveness in pseudopregnant and pregnant rats: role of maternal factors

1989 ◽  
Vol 257 (4) ◽  
pp. R866-R871 ◽  
Author(s):  
M. S. Paller ◽  
G. Gregorini ◽  
T. F. Ferris
Keyword(s):  
Vascular Reactivity ◽  
Pressor Response ◽  
Ang Ii ◽  
Maternal Factors ◽  
Synthesis Inhibitor ◽  
Pregnant Rats ◽  
Plasma Progesterone ◽  
Early Increase ◽  
In Pregnancy

During pregnancy the pressor response to vasoconstrictor substances such as angiotensin II (ANG II) is diminished, and renal, uterine, and vascular prostaglandin (PG) production may increase. However, little is known about the factors that alter vascular reactivity or stimulate PG synthesis during pregnancy. To ascertain whether these factors are of maternal or fetal-placental origin, we studied vascular reactivity and urinary PGE excretion in pseudopregnant rats. Pseudopregnant rats had plasma progesterone and weight gain similar to that observed in pregnant rats. Urinary PG excretion in nonpregnant rats was approximately 70 ng/24 h and remained constant during a 12-day observation. In contrast, urinary PG excretion in both pregnant and in pseudopregnant rats rose to levels approximately twice control within 4-6 days. The pressor response to ANG II was diminished in pseudopregnant rats compared with nonpregnant rats. When the PG synthesis inhibitor meclofenamate was given there was no change in the pressor response to ANG II in nonpregnant animals, but in pseudopregnant animals meclofenamate produced a significant increase in the pressor response to ANG II. The pressor response to norepinephrine and arginine vasopressin (AVP) was not diminished in pseudopregnant animals, and meclofenamate did not increase the pressor response to these agents. Therefore, a developing fetus and placenta is not necessary for the decrease in pressor response to ANG II nor for the early increase in urinary PGE excretion. Like in pregnancy, the pressor response to ANG II was increased after meclofenamate in pseudopregnancy. Increased PG production may, therefore, be partly responsible for the decrease in pressor responsiveness to ANG II. However, pseudopregnancy, unlike pregnancy, did not affect pressor responsiveness to norepinephrine or AVP. Both maternal and fetal-placental factors seem required for the reduction in responsiveness to norepinephrine and AVP in pregnancy.

scholarly journals Lysophosphatic acid modulates prostaglandin secretion in the bovine uterus

Reproduction ◽  
2009 ◽  
Vol 137 (1) ◽  
pp. 95-105 ◽  
Author(s):  
Izabela Woclawek-Potocka ◽  
Junichi Komiyama ◽  
Jean Sebastian Saulnier-Blache ◽  
Edyta Brzezicka ◽  
Mamadou Moussa Bah ◽  
...  
Keyword(s):  
Gene Expression ◽  
Estrous Cycle ◽  
Dehydrogenase Activity ◽  
Lysophosphatidic Acid ◽  
Early Pregnancy ◽  
Reproductive Tract ◽  
Hydroxysteroid Dehydrogenase ◽  
Lpa Receptor

Lysophosphatidic acid (LPA) modulates prostaglandin (PG) synthesis via LPA receptor 3 (LPAR3) in the murine endometrium. The lack of functional LPAR3 in mice may lead to embryo mortality. In the present study, we examined the role of LPA in the bovine uterus. We confirmed that LPA is locally produced and released from the bovine endometrium. Moreover, there are enzymes involved in LPA synthesis (phospholipase(PL)D2and PLA2G1B) in the bovine endometrium during estrous cycle and early pregnancy. Expression of the receptor for LPA (LPAR1) was positively correlated with the expression ofPGE2synthase(PGES) and negatively correlated with the expression ofPGF2αsynthase(aldose reductase with 20 α-hydroxysteroid dehydrogenase activity –PGFS) during early pregnancy.In vivoLPA induced P4 and PGE2secretion was inhibited by LPAR1 antagonist (Ki16425). The overall results indicate that LPA is locally produced and released from the bovine endometrium. Moreover,LPAR1gene expression in the endometrium during the estrous cycle and early pregnancy indicates that LPA may play autocrine and/or paracrine roles in the bovine uterus.LPAR1gene expression is positively correlated with the expression of the enzyme responsible for luteotropic PGE2production (PGES) in endometrium. In cow, LPA stimulates P4 and PGE2secretion. Thus, LPA in the bovine reproductive tract may indirectly (via endometrium) or directly support corpus luteum action via the increase of P4 synthesis and the increase of PGE2/PGF2αratio. It suggests that LPA may serve as an important factor in the maintenance of early pregnancy in cow.

scholarly journals Decline with Age in the Rate of Reduction of Progesterone to 20a-Hydroxypregn-4-en-3-one in the Blood of Perinatal Ruminants

1983 ◽  
Vol 36 (2) ◽  
pp. 183 ◽  
Author(s):  
CD Nancarrow
Keyword(s):  
Longitudinal Studies ◽  
Dehydrogenase Activity ◽  
Gestational Age ◽  
Hydroxysteroid Dehydrogenase ◽  
Adult Type ◽  
Sheep Blood ◽  
New Born ◽  
Final Volume ◽  
O 43

The activity of the enzyme 20IX-hydroxysteroid dehydrogenase present in erythrocytes of foetal and new-born ruminants has been determined by incubating 0�1 ml blood with 0�16,umol [4_'4C]_ progesterone for 15 min at 39�C in a final volume of 2 ml buffered saline. It was found that the activity, measured as ,umol 20IX-hydroxypregn-4-en-3-one produced from progesterone per millilitre of erythrocytes per hour, declined from levels at birth as high as 1'50,umol for sheep, 0'50,umol for goats and O' 43 ,umol for cattle to levels of around 0'11, O' 08 and O' 04 ,umol respectively by 30-60 days of age. This decline in activity was also apparent in blood taken from sheep foetuses in which longitudinal studies were possible and appeared to have begun prior to 35 days before term. The highest activity obtained was 2� 59 ,umol for foetal sheep blood taken at 115 days of gestation. It is suggested that the observed decline in 20IX-hydroxysteroid dehydrogenase activity is a function of the replacement of foetal erythrocytes with adult-type erythrocytes which begins around 120 days of gestational age and that the role of the enzyme is to maintain an appropriate progestational environment within the foetoplacental unit.

THE ROLE OF PROLACTIN IN THE REGULATION OF TESTICULAR FUNCTION: THE EFFECT OF PROLACTIN AND LUTEINIZING HORMONE ON 3β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE TESTES OF MICE AND RATS

1971 ◽  
Vol 50 (4) ◽  
pp. 619-623 ◽  
Author(s):  
A. A. HAFIEZ ◽  
J. E: PHILPOTT ◽  
A. BARTKE
Keyword(s):  
Luteinizing Hormone ◽  
Dehydrogenase Activity ◽  
Normal Mouse ◽  
Hydroxysteroid Dehydrogenase ◽  
Testicular Function ◽  
Hypophysectomized Rats ◽  
Dwarf Mice

SUMMARY Administration of 100 μg prolactin twice daily for 3 days increased 3β-hydroxysteroid dehydrogenase (3β-HSD) activity in the testes of dwarf mice compared with that found in the normal mouse. In hypophysectomized rats, prolactin (200 μg, same regimen) was without effect when given alone, whereas 5 μg luteinizing hormone (LH) alone injected twice daily, increased 3β-HSD activity to above normal. When prolactin and LH were administered in combination, 3β-HSD activity was raised to normal levels only.

Role of plasma progesterone concentration in early pregnancy of the ewe

1981 ◽  
Vol 21 (113) ◽  
pp. 562 ◽  
Author(s):  
FD Brien ◽  
IA Cumming ◽  
IJ Clarke ◽  
CS Cocks
Keyword(s):  
Early Pregnancy ◽  
Progesterone Level ◽  
Progesterone Concentration ◽  
Plasma Progesterone ◽  
Peripheral Plasma

Eighty-eight maiden and 125 mature Merino ewes were grazed on green irrigated pasture or given dry hay on a fallow area with or without a lupin grain supplement just before and during mating. Progesterone concentrations in peripheral plasma were measured at 12 d after coitus. Progesterone concentration was lower (2.27 vs 2.87 ng/ml, P < 0.001 ) when lupins were fed, and maiden ewes had higher progesterone concentrations than mature ewes (2.75 vs 2.36 ng/ml, P < 0.05). Pregnant ewes had higher progesterone concentrations than non-pregnant ewes (2.77 vs 2.36 ng/ml, P < 0.05), and ewes with two ovulations had higher progesterone concentrations than ewes with a single ovulation (3.13 vs 2.08 ng/ml, P < 0.001). There was an interaction between pasture type and lupin supplement, with lupins depressing progesterone level more on green irrigated pasture (lupins 2.11 ng/ml, no lupins 3.00 ng/ml, P < 0.05) than on dry pasture (lupins 2.45 ng/ml, no lupins 2.74 ng/ml, P < 0.05). The results confirm that a high plane of nutrition at mating lowers progesterone levels in plasma and suggest that this may be a factor in the increase in embryo deaths when ewes are fed lupin grain supplements.

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