Potential role for lipoxygenase products of arachidonic acid in prostaglandin F2α-stimulated oxytocin release from the ovine corpus luteum

1994 ◽  
Vol 142 (1) ◽  
pp. 47-52 ◽  
Author(s):  
R G Cooke ◽  
N Ahmad
Keyword(s):  
Arachidonic Acid ◽  
Corpus Luteum ◽  
Potential Role ◽  
Prostaglandin F2α ◽  
Nordihydroguaiaretic Acid ◽  
Luteal Function ◽  
Lipoxygenase Inhibition ◽  
Lipoxygenase Products ◽  
Oxytocin Release ◽  
Prostaglandin F

Abstract Intrauterine administration of nordihydroguaiaretic acid (NDGA) will maintain luteal function in sheep and also suppress the release of both oxytocin and prostaglandin F2α (PGF2α) suggesting that 5-lipoxygenase products of arachidonic acid may be involved in ovine luteolysis. During luteolysis, uterine PGF2α is considered to be the major stimulus for the secretion of luteal oxytocin, and we report the effects of 5-lipoxygenase inhibition, via intrauterine NDGA administration, on the ability of PGF2α to effect such secretion. In the NDGA-treated ewes, luteal function was maintained and oestrus delayed, the duration of the oestrous cycle (20 ±1 days; mean ± s.d.; n=9) being significantly (P<0·01) longer than in intact controls (15 ± 1 days, n=4). Jugular infusions of PGF2α did not stimulate luteal secretion of oxytocin, the effects being comparable with those in ovariectomized ewes. In intact ewes receiving intrauterine infusions of vehicle only, PGF2α produced marked increases in luteal secretion of oxytocin. Also, preinfusion or basal concentrations of oxytocin in this group of ewes (6·6 ± 1·9 pg/ml) were significantly (P<0·01) greater than in either the NDGA-treated (3·1 ± 1·1 pg/ml) or ovariectomized (3·0 ± 0·6 pg/ml) ewes. The results suggest involvement of 5-lipoxygenase products of arachidonic acid in the release of oxytocin from the ovine corpus luteum. Journal of Endocrinology (1994) 142, 47–52

Prostaglandin F2α and oxytocin release during persistence of the corpus luteum in sheep

1987 ◽  
Vol 115 (4) ◽  
pp. 469-477 ◽  
Author(s):  
S. B. Hooper ◽  
G. D. Thorburn
Keyword(s):  
Corpus Luteum ◽  
Prostaglandin F2α ◽  
Pulse Frequency ◽  
Ovarian Vein ◽  
Luteal Regression ◽  
Oxytocin Release ◽  
Prostaglandin F ◽  
Frequency Of Stimulation

Abstract. Oxytocin (OT), progesterone and prostaglandin F2α (PGF2α) concentrations were measured in the utero-ovarian vein (UOV) of ewes which displayed persistence of the corpus luteum (CL). During the period of expected luteolysis, the frequency of OT and PGF2α pulses in the UOV was significantly (P < 0.005 for both) lower in ewes with persistent CLs, compared with ewes that underwent normal luteal regression. In contrast, the amplitude of both OT and PGF2α pulses was similar in both groups of animals. It is suggested that persistence of the CL resulted from a decreased PGF2α pulse frequency, which may have arisen from a decreased frequency of stimulation by OT. In two persistent CL ewes, however, it appeared that a failure at the level of the uterus may have contributed to the observed decrease in PGF2α release. Although a PGF2α analogue (Lutalyse) infusion into the uterine vein of two ewes with persistent CLs failed to induced luteolysis, it did stimulate a large release of OT into the UOV. This suggests that persistent CLs maybe more resistant to PGF2α and, that at day 22 post-oestrus, these CLs are capable of releasing large quantities of OT into the UOV.

Expression of prostaglandin G/H synthase (PGHS) and heat shock protein-70 (HSP-70) in the corpus luteum (CL) of prostaglandin F2α-treated immature superovulated rats

2004 ◽  
Vol 82 (6) ◽  
pp. 363-371 ◽  
Author(s):  
R M Narayansingh ◽  
M Senchyna ◽  
M M Vijayan ◽  
J C Carlson
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Protein Expression ◽  
Corpus Luteum ◽  
Heat Shock Protein 70 ◽  
Prostaglandin F2α ◽  
Sampling Period ◽  
Immunoblot Analysis ◽  
Hsp 70 ◽  
Prostaglandin F

In this study we examined the mechanism of corpus luteum (CL) regression by measuring changes in expression of prostaglandin G/H synthase-1 (PGHS-1) and -2 (PGHS-2) in day 4 CL and inducible heat shock protein 70 (HSP-70) in day 4 and day 9 CL of immature superovulated rats. The rats were superovulated and treated with 500 µg of prostaglandin F2α (PGF2α) on day 4 or day 9 after CL formation. Ovaries and serial blood samples were removed during the 24-hour period following treatment. Plasma progesterone was determined by radioimmunoassay while mRNA abundance and protein expression were assessed by semiquantitative RT-PCR and immunoblot analysis, respectively. One hour after PGF2α, both day 4 and day 9 rats exhibited a significant decrease in progesterone secretion; however, there was a greater decrease in day 9 rats. In ovarian samples removed on day 4, there was a significant increase in mRNA for PGHS-2 at 1 hour after PGF2α. PGHS-1 mRNA content remained unchanged. Immunoblot analyses showed an increase in PGHS-2 protein expression only at 8 h. There were no changes in PGHS-1 protein expression. In day 9 rats, ovarian HSP-70 protein levels increased by 50% after PGF2α injection; however, on day 4 there was no change in expression of this protein over the sampling period. These results suggest that expression of PGHS-2 may be involved in inhibiting progesterone production and that expression of HSP-70 may be required for complete CL regression in the rat.Key words: rat, prostaglandin F2α, corpus luteum, prostaglandin G/H synthase, heat shock protein-70.

Collagen solubility and tensile properties of the rat uterine cervix in late pregnancy: effects of arachidonic acid and prostaglandin F2α

1982 ◽  
Vol 95 (3) ◽  
pp. 341-347 ◽  
Author(s):  
Keith Hillier ◽  
R. M. Wallis
Keyword(s):  
Acetic Acid ◽  
Arachidonic Acid ◽  
Tensile Properties ◽  
Uterine Cervix ◽  
Prostaglandin F2α ◽  
Late Pregnancy ◽  
Collagen Structure ◽  
Collagen Concentration ◽  
Pregnant Animal ◽  
Prostaglandin F

The collagen concentration in rat uterine cervix was less on day 18 of pregnancy than in the non-pregnant animal but did not diminish further as pregnancy proceeded. The solubility of cervical collagen in warm acetic acid (0·5 mol/l) was increased on day 22 compared with days 19, 20 and 21 of pregnancy, and there was a positive correlation of increasing solubility with the tissue rate of creep (a measure of reducing stiffness of the cervix). Treatment of rats subcutaneously with arachidonic acid or prostaglandin F2α (PGF2α) on day 18 of pregnancy decreased the stiffness of the tissue when assessed on day 19 and this was accompanied by increased solubility in cold saline (0·45 mol/l), cold acetic acid and warm acetic acid and a reduction in collagen concentration. These results suggest that collagen properties rather than concentration are important in determining the stiffness of the rat uterine cervix at term and that exogenous PGF2αand arachidonic acid cause biochemical changes in collagen structure unlike those seen at term in untreated animals.

scholarly journals Diestrous Ovulations in Pregnant Mares as a Response to Low Early Postovulatory Progestogen Concentration

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2249
Author(s):  
Carolina T. C. Okada ◽  
Martim Kaps ◽  
Javier Perez Quesada ◽  
Camille Gautier ◽  
Jörg Aurich ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Prostaglandin F2α ◽  
Tissue Response ◽  
P Value ◽  
Luteal Function ◽  
Luteal Tissue ◽  
Underlying Causes ◽  
Hypothalamic Pituitary Axis ◽  
Effect Of Treatment ◽  
Response Detection

Spontaneous prolongation of the luteal phase has been described in horses, but the underlying causes are still unclear. The present study investigated details of gonadotrophin and progestogen secretion in pregnant mares (n = 11) with or without experimentally reduced early postovulatory luteal function. From days 0 to 3 after ovulation, they were treated with the prostaglandin F2α (PGF2α) analogue cloprostenol or left untreated. After conceptus collection on day 34, they were assigned to the opposite treatment. Mares were affiliated to the group primary corpus luteum (n = 6) or diestrous corpus luteum (n = 5) depending on diestrous corpus luteum (CL) detection in the PGF pregnancy. For statistical comparisons, a p-value < 0.05 was significant. There was an effect of treatment (p < 0.01), but not of group on progestogen concentration. The concentration of LH was higher in PGF-treated than in untreated pregnancies (p < 0.05), but did not differ between groups. The FSH concentration did not differ between groups nor treatments. The total luteal tissue area was greater in mares with a diestrous ovulation during the PGF treatment pregnancy. Low progestogen concentration in the early postovulatory phase diminish the negative feedback on the hypothalamic-pituitary axis in early pregnancy and, thus, stimulate a luteal tissue response. Detection of secondary CL at the time of pregnancy examination in mares may reflect that early post-ovulatory progestogen concentrations were low.

CONCENTRATION OF PROSTAGLANDIN F2α AND STEROIDS IN THE HUMAN CORPUS LUTEUM

1977 ◽  
Vol 73 (1) ◽  
pp. 115-122 ◽  
Author(s):  
I. A. SWANSTON ◽  
K. P. McNATTY ◽  
D. T. BAIRD
Keyword(s):  
Menstrual Cycle ◽  
Corpus Luteum ◽  
Luteal Phase ◽  
Prostaglandin F2α ◽  
Corpora Lutea ◽  
Progesterone Concentration ◽  
Late Luteal Phase ◽  
Prostaglandin F ◽  
Human Corpus Luteum

SUMMARY The concentration of prostaglandin F2α (PGF2α), progesterone, pregnenolone, oestradiol-17β, oestrone, androstenedione and testosterone was measured in corpora lutea obtained from 40 women at various stages of the menstrual cycle. The concentration of PGF2α was significantly higher in corpora lutea immediately after ovulation (26·7 ± 3·9 (s.e.m.) ng/g, P < 0·005) and in corpora albicantia (16·3 ± 3·3 ng/g, P < 0·005) than at any other time during the luteal phase. There was no correlation between the concentration of PGF2α and that of any steroid. The progesterone concentration was highest in corpora lutea just after ovulation (24·9 ± 6·7 μg/g) and in early luteal groups (25·7 ± 6·8 μg/g) but declined significantly (P < 0·05) to its lowest level in corpora albicantia (1·82 ± 0·66 μg/g). The concentration of oestradiol-17β in the corpus luteum and luteal weight were significantly greater during the mid-luteal phase than at any other stage (concentration 282 ± 43 ng/g, P < 0·05; weight 1·86 ± 0·18 g, P < 0·005). The results indicate that regression of the human corpus luteum is not caused by a rise in the ovarian concentration of PGF2α in the late luteal phase of the cycle.

Studies on the roles of phospholipase A2 and eicosanoids in the regulation of corticotrophin secretion by rat pituitary cells in vitro

1991 ◽  
Vol 130 (1) ◽  
pp. 21-32 ◽  
Author(s):  
A. M. Cowell ◽  
R. J. Flower ◽  
J. C. Buckingham
Keyword(s):  
Arachidonic Acid ◽  
Platelet Activating Factor ◽  
Nordihydroguaiaretic Acid ◽  
Cyclooxygenase Inhibitors ◽  
Pituitary Cells ◽  
Lipoxygenase Inhibitor ◽  
Acth Secretion ◽  
Lipoxygenase Inhibitors ◽  
Prostaglandin F

ABSTRACT Dispersed anterior pituitary cells were used to investigate the possible roles of phospholipid metabolites released by phospholipase A2 (PLA2) in the control of immunoreactive ACTH (ir-ACTH) secretion in vitro. PLA2 (15 600–62 500 U/1), the PLA2 activator melittin (0·5–20 mg/l) and arachidonic acid (1 mmol/l) all produced increases in ir-ACTH release from the cells, whilst platelet-activating factor (PAF), prostaglandin F2α (PGF2α), the prostacyclin analogues iloprost and BW245C, the thromboxane A2 (TXA2) analogue U46619, and the leukotrienes LTB4 and LTC4 were ineffective in this respect. PGF2α (100 nmol/l and 1 μmol/l), iloprost (1 μmol/l) and BW245C (100 nmol/l and 1 μmol/l) depressed corticotrophin-releasing factor-41-induced ir-ACTH secretion, while the PAF antagonist BN52021 (10 and 100 μmol/l) and LTC4 (100 nmol/l and 1 μmol/l) had no discernable effects. The secretory responses of the cells to hypothalamic extracts (0·2 hypothalami/ml) and arachidonic acid (1 mmol/l) were generally unaffected by the cyclooxygenase inhibitors ibuprofen (10 and 100 μmol/l) and indomethacin (10 μmol/l), the TXA2 synthetase inhibitor imidazole (10 μmol/l–1 mmol/l), the lipoxygenase inhibitor nordihydroguaiaretic acid (10 and 100 μmol/l) and the dual cyclo-oxygenase/lipoxygenase inhibitors phenidone (1–100 μmol/l) and BW755C (10 and 100 μmol/l). They were, however, inhibited by the dual cyclo-oxygenase/lipoxygenase inhibitor eicosatetraynoic acid (10 and 100 μmol/l), which also blocks epoxygenase and PLA2 activity and by the cytochrome P450 inhibitor SKF-525A (1 mmol/l). The results suggest that the stimulatory effects of PLA2 and arachidonic acid on ir-ACTH secretion are not effected by products generated by the cyclo-oxygenase or lipoxygenase pathways but may be mediated by metabolites generated by the cytochrome P450 pathway. Journal of Endocrinology (1991) 130, 21–32

Endocrine changes, with emphasis on 13, 14–dihydro–15–keto–prostaglandin F2α and corticosteroids, before and during parturition in dromedary camels (Camelus dromedarius)

1994 ◽  
Vol 122 (2) ◽  
pp. 315-323 ◽  
Author(s):  
M. S. El-Belely
Keyword(s):  
Plasma Concentrations ◽  
Prostaglandin F2α ◽  
Dromedary Camel ◽  
Total Plasma ◽  
Dromedary Camels ◽  
Luteal Function ◽  
The Third ◽  
Tenfold Increase ◽  
Prostaglandin F ◽  
Consistent Increase

SUMMARYA study was conducted on eight preparturient camels which were kept in individual stalls adjacent to the Cairo abattoir during 1989. Four novel phenomena are described in this paper: (i) a significant (P < O·05) prepartum decrease in plasma concentrations of progesterone evident over the 48 h preceding parturition; (ii) a remarkably consistent increase in total plasma unconjugated oestrogens, commencing 2–4 days prior to parturition and peaking in excess of 200 pg/ml for c. 2 h before delivery; (iii) a tenfold increase to 5·4±0·19 ng/ml (mean±S.E.) in plasma concentrations of 13, 14-dihydro-15-keto-prostaglandin F2α (PGFM) between days –10 and – 1, showing a sudden and large increase during the 5 h prior to delivery; and (iv) three peaks of total plasma corticosteroids during the 4 h preceding delivery, with the third peak showing the greatest magnitude (24·0±3·11 ng/ml). These results suggest that the dromedary camel is an example of a species in which luteal secretion of progesterone, especially 3α-dihydroprogesterone, is required throughout pregnancy and in which cessation of luteal function, associated with a rapid increase in the oestrogen: progesterone ratio and the secretion of prostaglandin F2α (PGF2α), is a requirement for parturition.

Luteal function in sheep injected with prostaglandin F2α directly into the corpus luteum

1976 ◽  
Vol 11 (1) ◽  
pp. 133-142
Author(s):  
W.A. Chamley ◽  
J.D. O'Shea
Keyword(s):  
Corpus Luteum ◽  
Prostaglandin F2α ◽  
Luteal Function
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