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PubMed2001

Management of the extremely preterm infant: is the replacement of estradiol and progesterone beneficial?

This review presents data to suggest that postnatal estradiol and progesterone replacement therapy may be beneficial in preterm infants. During pregnancy, maternal plasma levels of estradiol and progesterone increase up to 100-fold compared to the nonpregnant status. The fetus is also exposed to these increasing hormone levels. After delivery, estradiol and progesterone levels drop by a factor of 100 within 1 day. Whereas this is a physiological condition for an infant born at term, preterm delivery means withdrawal from the placental supply of these hormones at an earlier developmental stage. Seventy years ago, the idea was raised that preterm infants may benefit from the replacement of estrogens. Studies in which estrogen was injected subcutaneously showed only a slightly better bodyweight gain compared to placebo-treated controls and therefore routine use was not established. The effective treatment of postmenopausal osteoporosis with hormone replacement therapy led to a pilot study of estradiol and progesterone therapy to prevent osteopenia of prematurity. The highest median bone mineral accretion rate was found in the replacement group when the supplementation with calcium and phosphorus was also sufficient. None of the previous studies dealing with estrogen replacement controlled for achieved plasma levels of estradiol in the infants. In our controlled randomised pilot study with 30 preterm infants (15 in each group), we aimed to maintain intra-uterine plasma levels of estradiol and progesterone. Preterm infants with replacement of estradiol and progesterone for 6 weeks postnatally showed trends to higher bone mineral accumulation. In addition, a trend towards a lower incidence of chronic lung disease was found. Neurodevelopmental follow-up showed normal psychomotor development in infants given estradiol and progesterone, whereas the untreated infants (controls) showed a trend towards delayed development. Recent research emphasises that estradiol and progesterone may be important for brain development. Thus, while there is data indicating that postnatal estradiol and progesterone replacement therapy may be beneficial in preterm infants, experience with this new therapy is limited and extensive research is needed to address the potential benefits and to rule out adverse effects.

Estrogen Replacement Therapy↗

PubMed2006

The role of intradermal skin testing and patch testing in the diagnosis of autoimmune progesterone dermatitis.

Autoimmune progesterone dermatitis is a rare clinical condition in which patients display hypersensitivity to endogenous progesterone. It manifests as a cyclical cutaneous eruption that flares during the luteal phase of the menstrual cycle, when progesterone levels peak, and resolves partially or completely a few days after menses. Its cutaneous manifestations are variable and include urticaria, eczematous eruptions, vesiculopustular eruptions, fixed drug eruptions, stomatitis, erythema multiforme, and anaphylaxis. Autoimmune progesterone dermatitis has been diagnosed previously with intradermal skin testing or intramuscular progesterone challenge. Treatment of progesterone hypersensitivity generally consists of ovulation inhibition with pharmaceutical agents or oophorectomy; other therapies (eg, thalidomide) have also been used with success. We report a case of cyclical erythema multiforme (EM) induced by hypersensitivity to endogenous progesterone in a patient with a history of past oral contraceptive use. After herpes simplex virus was ruled out as an etiologic factor, a diagnosis of progesterone hypersensitivity was confirmed with intradermal skin testing. Results of subsequent patch testing with various progesterone derivatives were negative. The EM outbreaks were suppressed temporarily by continuous administration of Loestrin (ethinyl estradiol plus norethindrone), which also increased the responsiveness of the outbreaks to prednisone tapers.

Adult↗

PubMed1996

Relationship between circulating progesterone and conception at the first postpartum estrus in young primiparous beef cows.

The objective of this study was to determine whether patterns of change in concentration of progesterone in circulation of primiparous beef cows were related to conception rates at the first postpartum estrus. Data were collected over 2 yr from crossbred primiparous 2-yr-old cows (n = 77). Cows were artificially inseminated when estrus was detected between 3 and 20 (yr 1) or 3 and 23 (yr 2) wk after parturition. Cows were exposed to intact bulls for 32 (yr 1) or 21 d (yr 2) after the periods of AI, and estrus detection also occurred during the period when natural mating occurred. After parturition, blood samples were collected twice weekly to determine time of transient (less than 1 wk) and sustained increases (more than 1 wk) in progesterone of more than 1 ng/mL of serum. Mean times from parturition to transient increase in progesterone, first estrus, conception, and sustained increase in progesterone were 91, 100, 108, and 105 d, respectively. Sixty-four percent of the cows conceived as a result of AI at the first estrus that was detected after parturition, 32% conceived at a subsequent estrus, and 4% failed to conceive. In 31.1% of the cows, a transient increase in progesterone was not detected before the first estrus after calving. Conception as a result of AI at the first estrus after calving was less if a transient increase in progesterone did not precede estrus (76 vs 41%; P < .01). These data indicate that the majority of cows have increases in progesterone before the first postpartum estrus. If the transient pre-estrus increase in progesterone occurs in postpartum cows, there seems to be an enhanced conception rate as compared with cows without the increase in progesterone before their first estrus following parturition.

Aging↗

PubMed1996

Effects of growth hormone, prolactin, insulin-like growth factors, and gonadotropins on progesterone secretion by porcine luteal cells.

Growth hormone (GH) and IGF-I have receptors within the corpus luteum (CL) and stimulate CL function. Our objective was to investigate the effects of GH, prolactin (PRL), IGF-I, IGF-II, LH, and FSH on progesterone secretion by porcine luteal cells during mid-pregnancy. Gilts (crossbred Yorkshire/Landrace) were slaughtered on d 44 of pregnancy and CL were collected. Large and small luteal cells (LLC and SLC, respectively) were obtained from dissociated CL and separated by elutriation. Luteal cells were incubated with 0, 1, 10, or 100 ng/mL of GH, PRL, IGF-I, IGF-II, LH, and FSH or combinations of 10 ng/mL of these reagents for 24 or 48 h. Culture media were harvested and concentrations of progesterone analyzed by radioimmunoassay. Growth hormone, PRL, and IGF-I increased (P < .05; 100 ng/mL dose) concentrations of progesterone in media of LLC. Insulin-like growth factor-II, LH, and FSH had no effect on progesterone in LLC cultures. In SLC cultures, GH, PRL, IGF-I, IGF-II, and FSH failed to stimulate progesterone secretion, whereas LH increased progesterone secretion (linear effect of dose; P < .05). Combinations (10 ng/mL each hormone) of GH and IGF-I or PRL and IGF-I increased progesterone secretion by LLC compared with control, GH, PRL, or IGF-I alone (P < .05). Similar combinations of GH or PRL with IGF-I had no effect on SLC. Conclusions are that GH and PRL are stimulatory to progesterone secretion by LLC (location of GH receptor) and SLC are responsive to LH during mid-pregnancy. Both GH and PRL are synergistic with IGF-I for increased progesterone secretion.

Animals↗

PubMed2003

Effect of pre- and postmating nutritional manipulation on plasma progesterone, blastocyst development, and the oviductal environment during early pregnancy in gilts.

Two experiments were conducted to determine mechanisms mediating effects of nutritional manipulation before and after mating on embryonic survival in pigs. Experiment 1 studied the mechanisms by which continued high feeding levels after mating result in differences in plasma progesterone during early pregnancy. Gilts fed 2.0 times maintenance energy requirements either remained on this high level or feed was reduced to 1.5 times maintenance immediately after mating. Ovarian, oviductal, and jugular vein progesterone concentrations were determined 72 h after onset of estrus, and samples taken every 4 h were used to determine LH and progesterone during the periestrous period. Treatment did not affect peripheral progesterone concentrations, the timing or rate of rise of progesterone, or progesterone in ovarian, oviductal, or jugular veins at the time of surgery. Time after the LH peak was highly correlated (P = 0.0001) with jugular progesterone concentrations, but not with those in oviductal and ovarian veins, suggesting that responses in the reproductive tract mediated by peripheral progesterone concentrations will be temporally different to effects within tissues supplied by the ovarian and oviductal vasculature. Experiment 2 studied mechanisms mediating nutritional manipulation in the preovulatory period on postovulatory reproductive function, using feed restriction during the first (RH) or second (HR) week of the estrous cycle. Surgeries were performed 12 to 20 h after ovulation, and fertilized oocytes were cultured for 144 h in vitro. Ovulation rate was not affected by previous nutritional regimen. Fertilization rate was higher (P = 0.056) in RH vs HR gilts, but development of cultured oocytes was not affected by treatment. There were no treatment differences in peripheral or oviductal plasma progesterone, estradiol, or insulin-like growth factor-I (IGF-I) at surgery, or in porcine oviductal secretory protein abundance and IGF-I concentrations in oviduct flushings, but treatment affected total protein concentration (P = 0.002). These results indicate that either previous nutritional treatment does not affect the early developmental competence of fertilized oocytes in vitro or differences in developmental competence of oocytes are not expressed up to the early blastocyst stage. However, the lack of an effect of previous nutrition on steroids in the local oviductal circulation may also be related to the lack of effects on oviductal function and embryonic development.

Animal Nutritional Physiological Phenomena↗

PubMed2002

Biology of progesterone action during pregnancy recognition and maintenance of pregnancy.

Progesterone is the hormone of pregnancy and unequivocally required in all mammals for maternal support of conceptus (embryo/fetus and associated membranes) survival and development. The actions of progesterone are mediated by the progesterone receptor (PR). However, the endometrial lumenal (LE) and glandular epithelia (GE) of a number of species exhibit a loss of PR expression prior to the stages of uterine receptivity and implantation. In sheep, PR expression becomes undetectable in the endometrial LE after Day 11 and then in the GE after Day 13. Loss of PR in the GE appears to be required for onset of differentiated functions in terms of production of secretory proteins, such as uterine milk proteins (UTMP) and osteopontin (OPN). Therefore, the actions of progesterone on endometrial epithelia during most of gestation appear to be mediated by the endometrial stroma that remains PR-positive throughout pregnancy. Stromal cells produce several growth factors, such as hepatocyte growth factor (HGF) and fibroblast growth factors-7 and -10 (FGF-7, FGF-10), that have receptors expressed specifically in the endometrial epithelia. These factors may be progesterone-responsive and mediate epithelial-mesenchymal interactions that are crucial for support of pregnancy. Studies of the uterine gland knockout (UGKO) ewe indicate that uterine glands and, by default, their secretions are required for peri-implantation conceptus survival and growth. A complex servomechanism, involving hormones from the ovary and conceptus as well as endogenous betaretroviruses expressed in the endometrial LE and GE, is proposed to regulate endometrial gland differentiation and function during gestation. At estrus, estrogen increases PR expression in the endometrial epithelia. High levels of endogenous Jaagsiekte sheep retroviruses (enJSRVs) are expressed in the PR-positive endometrial LE and GE in response to increasing progesterone and are hypothesized to stimulate trophoblast proliferation and production of interferon (IFN) tau. IFN tau, the pregnancy recognition hormone produced by the trophoblast from Days 10 to 21, acts in a paracrine manner on the PR-negative endometrial LE and superficial GE to inhibit transcription of estrogen receptor alpha (ER) and oxytocin receptor (OTR) genes. These actions of IFN tau maintain progesterone production from the corpus luteum by abrogating release of luteolytic pulses of prostaglandin F2 alpha (PGF) from the endometrial epithelium. The antiluteolytic effects of IFN tau are dependent on progesterone. Progesterone stimulation over 8-10 days suppresses expression of the PR gene in the LE and then GE. Loss of the PR in the LE is concomitant with decreases in mucin glycoprotein one (MUC-1), an inhibitor of blastocyst implantation. As the conceptus begins implantation on Day 15, the binucleate trophectodermal cells then differentiate and produce placental lactogen (PL), a member of the prolactin (PRL) and growth hormone (GH) family. PL stimulates GE proliferation and production of secretory proteins, such as UTMP and OPN. Interestingly, the effects of PL on the GE appear to require the absence of PR and prior exposure to IFN tau. During mid-pregnancy, the mononuclear trophectodermal cells produce GH that can also act on a progestinized uterus to stimulate GE hypertrophy and secretory function. The actions of this servomechanism are proposed to stimulate GE hyperplasia from Days 20 to 50 and then GE hypertrophy and maximal differentiated function after Day 50 when the majority of fetal growth and development occurs during gestation.

Animals↗

PubMed1990

Comparison of methods for the synchronization of estrous cycles in dairy cows. 1. Effects on plasma progesterone and manifestation of estrus.

Dairy cows (n = 571) were treated with 1) one or two injections of prostaglandin F2 alpha given 11 or 14 d apart, 2) two injections given 14 d apart and a progesterone coil inserted 8 d after the first injection for a 7-d period; or 3) a coil inserted for 7 d and prostaglandin injected 1 d before its removal. Cows given two prostaglandin injections that conceived had higher progesterone concentrations during the luteal phase preceding AI than did cows that did not conceive. Cows with progesterone coils that conceived did not have higher progesterone concentrations than did cows that did not conceive. Older cows had lower progesterone concentrations than younger ones, and they appeared in estrus earlier after treatment. In four daily observations, 75% of cows were seen in estrus within 7 d after treatment. Cows mounting two or more times had a conception rate (62%) similar to that of cows that stood to mount. Fewer cows (56%) treated with prostaglandin that had low concentrations of progesterone appeared in estrus than did cows with high progesterone (84%). Cows treated with prostaglandin differ from cows treated with progesterone coils in respect to manifestation of estrus and to the relationship between plasma progesterone and conception.

Administration, Intravaginal↗

PubMed1990

Comparison of methods for the synchronization of estrous cycles in dairy cows. 2. Effects of progesterone and parity on conception.

Three experiments with 571 dairy cows indicated that significantly more primiparous cows given two prostaglandin F2 alpha injections 14 d apart conceived within 30 d of first AI than did cows given two injections 11 d apart (84 vs. 62%). Fewer multiparous cows given two injections 14 d apart and inseminated after estrus conceived than did cows given two injections and a progesterone intravaginal coil inserted 8 d after the first injection (42 vs. 66%). Fewer cows given one injection of prostaglandin and inseminated at estrus conceived than did cows given two injections 14 d apart and a progesterone coil (39 vs. 66%). Conception rates of cows given two prostaglandin injections were positively related to plasma progesterone concentrations 2 and 4 d before the second injection (r = .81 and .86). Cows with progesterone concentrations below 5 ng/ml, 2 d before the second prostaglandin injection, and synchronized by two prostaglandin injections or by two injections and a progesterone coil had conception rates of 36 and 63%, respectively. Cows with progesterone concentrations above 5 ng/ml had a conception rate of 75 and 46% in the two treatments, respectively. Conception after estrus synchronization depends on the method and on the plasma concentrations of progesterone. Progesterone coils may be used before AI to enhance fertility in cows with low progesterone concentrations.

Administration, Intravaginal↗

PubMed1993

Progesterone antagonist mifepristone (RU 486) decreases cardiotoxicity of cocaine.

RU 486, a potent progesterone antagonist, was used to determine whether RU 486 blocks the enhanced cardiotoxicity of cocaine mediated by progesterone upon rat papillary muscles. Groups of nonpregnant rats were pretreated with: progesterone for 3 days (n = 12); progesterone + RU 486 for 3 days (n = 12); progesterone for 3 days + single low dose RU 486, progesterone for 3 days + single high dose RU 486, and RU 486 for 3 days (n = 6); or were untreated (n = 12). Papillary muscles from these groups were electrically paced during exposure to cocaine concentrations ranging from 10(-14) M to 10(-3) M. One group (n = 6) was pretreated with RU 486, but not exposed to cocaine. The results showed that all muscles from rats pretreated with RU 486 for 3 days were functional when exposed to cocaine concentrations one to four orders of magnitude higher than tolerated by muscles from untreated or progesterone-treated rats. As indicated by alterations in contraction response patterns, RU 486 treatment for 3 days reversed progesterone-enhanced cardiotoxicity of cocaine. Single low dose and high dose RU 486 administrations also reversed progesterone's effects upon cocaine-induced cardiotoxicity.

Analysis of Variance↗

PubMed1982

Relationship between progesterone and egg production in pheasants.

A radioimmunoassay was developed to measure progesterone concentration in sera of immature and mature female pheasants. The antiserum to progesterone was produced against progesterone-3-carboxymethyloxime: bovine serum albumin in female rabbits. Crossreactivity of the antiserum with 17 different steroids was tested and was less than 2% for all steroids except 5 alpha-pregnane-3,20-dione (18%) and pregnenolone (9%). Sensitivity of the standard curve was 2.7 pg. The within and between assay coefficients of variation were 7% and 14%, respectively. Blood samples were collected weekly starting when the birds were 17 weeks of age and continued until they were 1 year of age. Progesterone concentration was measured in all serum samples. Egg production was recorded daily for the individual hens. The relationship between progesterone concentration and egg production was studied. Average progesterone concentration prior to sexual maturity was significantly lower than at subsequent ages. There was a significant positive correlation between average progesterone concentration and average percent egg production within individual birds. Furthermore, statistically a significant amount of the variation in percent egg production was explained by differences in progesterone concentration. These results indicate that progesterone is important for egg production in pheasants, as it is in chicken and turkey hens.

Animals↗

PubMed1997

Effect of DL111-IT on progesterone biosynthesis and viability of rat luteal cells in vitro.

AIM: To study the influence of DL111-IT on progesterone biosynthesis of cultured luteal cells (LC). METHODS: LC viability was assessed with trypan blue dye exclusion and progesterone concentration was measured with radioimmunoassay. RESULTS: DL111-IT decreased the viability of LC after 24-h incubation, its ED50 being 7.7 (95% confidence limits: 7.1-8.5) mg.L-1. DL111-IT inhibited basal secretion of progesterone in a concentration-dependent manner, and 3 mg.L-1 decreased progesterone concentration by 25% vs control. DL111-IT 3 mg.L-1 also inhibited the stimulatory effect of forskolin (cAMP activator) 10 mumol.L-1 and pregnenolone [converted to progesterone by 3 beta-hydroxysteroid dehydrogenase-isomerase complex (3 beta-HSD)] 10 mumol.L-1 on progesterone production in cultured LC, and their inhibitory rates were 43% and 155%, respectively. At the same concentration, DL111-IT did not influence hCG-induced progesterone production. CONCLUSION: DL111-IT inhibited progesterone synthesis by suppressing the conversion of pregnenolone to progesterone (inactivating 3 beta-HSD) and suppressed the activity of cAMP. DL111-IT 6-24 mg.L-1 decreased the viability of LC.

Abortifacient Agents, Nonsteroidal↗

PubMed1975

[Determination of progesterone in peripheral blood-plasma as a diagnostic aid in female swine (author's transl.)].

The determination of the peripheral plasma level of progesterone was evaluated as a clinical aid in the gynaecological diagnosis of female pigs. The normal cyclic variation of the peripheral plasma level of progesterone was determined in six cross bred gilts (Swedish Landrace times Swedish Yorkshire Breed) which were examined daily for the stages of oestrus. The results of this investigation are given in fig. 1. Peripheral plasma levels of progesterone were determined in 16 gilts with the clinical diagnosis of "silent heat". Despite all 16 gilts being sexually mature none of them had shown clinical signs of heat. The gilts belonged to 3 different farms, on all of which there was a high incidence of "silent heat". At least two blood samples were drawn 7 days apart from each of the gilts. Of the gilts examined 12 had variations in peripheral plasma level of progesterone. Of these 12 animals only 5 had clinical signs of heat, although the farmer had been advised, from the progesterone analysis, on the probable day of occurrence of heat. In 3 of the gilts, treatment with hormones (PMSCG) elicited the standing reflex when they were placed with a boar. In Table I is given some examples of the relationship of clinical signs of heat and the peripheral plasma level of progesterone. The peripheral plasma level of progesterone was also used as an early pregnancy diagnosis test in gilts. The gilts used in this investigation were all artificially inseminated with deep frozen boar semen. The expected pregnancy rate after insemination was 50%. Blood samples were drawn 17-25 days after insemination of 84 gilts. Peripheral plasma level of progesterone equal to or higher than 7.5 ng/ml were considered to indicate pregnancy. All gilts were slaughtered 4 weeks after the insemination and the number of fetuses were counted. A correct pregnancy diagnosis by the estimation of peripheral plasma level of progesterone was obtained in 95.2% of the gilts. The incorrect diagnoses were all false positives, viz. non-pregnant gilts were diagnosed as pregnant.

Animals↗

PubMed2002

Modulatory effects of gonadotrophins and insulin-like growth factor on the secretion of inhibin A and progesterone by granulosa cells from chicken preovulatory (F1-F3) follicles.

The aim of this study was to compare the actions and interactions of gonadotrophins (LH and FSH) and an analogue of insulin-like growth factor I (LR3-IGF-I) on the secretion of inhibin A, inhibin B and progesterone by cultured chicken granulosa cells derived from the three largest (F1--F3) follicles of the preovulatory hierarchy. Treatment with LH or FSH promoted marked dose-(P < 0.0001) and time- (P < 0.0001) dependent increases in both inhibin A and progesterone secretion, with the magnitude of response (< 15-fold compared with basal) increasing over time in culture. Concentrations of inhibin B were below the detection limit in all samples. Initially, F1 cells were more LH-responsive than were F3 cells in terms of progesterone secretion (P < 0.02) but this difference between follicles decreased over time in culture. In contrast, LH-induced inhibin A secretion tended to be highest from F3 cells, although this was not significant. Cells from F3 follicles were consistently more FSH-responsive than F1 cells in terms of both progesterone (P < 0.01) and inhibin A (P < 0.02) secretion. Initially, F1 cells were more responsive to LR3-IGF-I than were F3 cells in terms of progesterone secretion (P < 0.001) but were less responsive in terms of inhibin A secretion (P < 0.001). Again, these inter-follicle differences decreased over time in culture (not significant on day 3 of treatment). Co-treatment experiments showed that LR3-IGF-I enhanced both LH- and FSH-induced secretion of inhibin A and progesterone in a time- (P < 0.001) and follicle- (P < 0.001) dependent way. Initially, F1 cells showed highest LR3-IGF-I enhancement of LH-induced inhibin A and progesterone secretion; in contrast, F3 cells showed the highest LR3- IGF-1 enhancement of FSH-induced inhibin A and progesterone secretion. These inter-follicle differences persisted over time in the case of FSH-induced hormone responses but not in the case of LH-induced responses, even though the relative degree of LR3-IGF-I enhancement increased markedly over time. Collectively, these data support a positive role for IGF-I, presumably of thecal origin, as an amplifier of gonadotrophin action on granulosa cell inhibin A and progesterone production by preovulatory chicken follicles.

Animals↗

PubMed1975

Progesterone concentration in placenta, molar tissue, and ovarian theca lutein cyst.

Progesterone concentrations in 2 full-term normal placentas, molar tissue from 3 cases of hydatidiform mole were measured by competitive protein binding. Sephadex LH-20 column chromatographic separation of extracts from these tissues showed that, in placental and molar tissue, 85 to 95% of the extracts were progesterone and very small amounts of 20 alpha-dihydroprogesterone and 17 alpha-hydroxyprogesterone. The concentration of progesterone in the placenta were 368.8 and 317.2 ng/g tissue, respectively, while in molar tissue the concentration were 2474.5, 1974.6, and 4146.0 ng/g tissue, respectively. Progesterone concentration in ovarian tissue was between 1121;2 and 1440.9 ng/g tissue. It is suggested that the high concentration of progesterone in molar tissue reflects functional capacity of the abnormal trophoblast in progesterone synthesis and accumulation of progesterone due to absence of a fetus. The lower concentration of progesterone in the ovary in molar pregnancy would appear to suggest that the ovary is a secondary source of progesterone in molar pregnancy.

Chorionic Gonadotropin↗

PubMed1976

Characteristics of progesterone-binding components in neoplastic mammary tissues of the rat.

Characteristics of [3H]progesterone-binding components were studied in cell-free preparations of two hormonally responsive tumors: the R3230AC mammary adenocarcinoma and 9,10-dimethyl-1,2-benzanthracene-induced mammary tumor of the rat. Progesterone-binding macromolecules from cytosols of both mammary neoplasms exhibited sedimentation coefficients of 3.5 to 4.0 S on sucrose gradients of either low or high ionic strength. From Scatchard analyses of titration data, apparent dissociation constants of 4 to 6 X 10(-8) M were determined for ligand-binding protein complexes from either tumor. Specific progesterone-binding capacities varied considerably, ranging from 150 to 650 fmoles/mg of cytosol protein. Optimal binding of [3H]progesterone was reached by 2 to 3 hr at 3 degrees, pH 7.4, and then decreased rapidly. Specificity studies indicated that cortisol, corticosterone, and triamcinolone acetonide competed effectively for [3H]progesterone-binding. This suggested that [3H] progesterone was bound largely to a macromolecule distinct from transcortin, which does not bind glucocorticoids containing 9alpha-fluoro groups. Aldosterone, as well as several androgens and estrogens, were weak competitors of binding except at high concentrations. The nature of the inhibition of progesterone-binding sites by triamcinolone acetonide and corticosterone was competitive. Concurrent titrations of [3H]progesterone and [3H]triamcinolone acetonide-binding sites demonstrated that their binding capacities were similar, considering the relative stabilities of the complexes. These results, which indicated that progesterone and glucocorticoids compete for the same binding site, suggest that these hormones may influence mammary gland differentiation and development by a common mechanism.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1991

Control of onset of breeding season in the mare and its artificial regulation by progesterone treatment.

Mean plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels and their pulse frequencies and the size of the largest ovarian follicle increased during spring in 12 mares studied twice monthly from deep anoestrus to the occurrence of the first ovulation of the breeding season. Mean FSH levels were reduced significantly in deep anoestrus and when a pre-ovulatory follicle was present, whereas mean LH levels were highest close to ovulation. Five of these 12 research mares and 20 of 40 maiden or barren Standardbred mares at a commercial studfarm were given daily intramuscular (i.m.) injections of 150 mg progesterone in oil for 12 days when their ovaries were considered to contain developing follicles on rectal palpation. In the research mares, the size of the largest follicle in the ovaries during progesterone treatment did not differ from pre-treatment or control values; nevertheless, the 5 mares ovulated synchronously 11.2 +/- 0.4 (s.d.) days after progesterone withdrawal. Ovulation was less synchronized after progesterone withdrawal in the commercial mares (23 +/- 9.5 [s.d.] days) and in neither group did progesterone treatment advance the mean date of first ovulation compared with the untreated control mares. Mean plasma LH levels were not affected and mean FSH levels were slightly, but not significantly, elevated during progesterone administration in the research mares. In contrast, mean FSH levels fell steadily with time in both the progesterone treated and the control commercial mares. LH and FSH pulse frequencies in treated and control research mares differed only after progesterone withdrawal, when pulse frequency was higher in controls. We conclude that exogenous progesterone has no consistent effect on follicular development and gonadotrophin secretion patterns in transition phase mares, and in the present study it did not advance the mean date of the first ovulation of the breeding season compared with untreated control mares.

Animals↗

PubMed1991

Post-partum and post-conceptional ovarian activity of dairy cows: evaluation based on progesterone profiles.

The progesterone level of milk was measured daily in 20 Icelandic dairy cows for 50-90 days post-partum and for 30-50 days post-conception by radioimmunoassay. In 40% of the cows the 1st post-partum ovarian cycle was shorter and the progesterone level lower than in normal cycles. The average duration of the 1st post-partum luteal phase was significantly shorter and the progesterone values lower than in the 2nd and 3rd phases. The progesterone level rose to a plateau at the onset of luteal function within 5 +/- 2 (mean +/- s.d.) days, whereas the decrease in progesterone at the end of the luteal phase was more rapid i.e. 3 +/- 1 days. The progesterone value for a normal interluteal phase was 1.5 +/- 1.3 nmol/l. However in 9 of 48 interluteal phases the progesterone values did not decline below 3 nmol/l. The average progesterone concentration was significantly increased during the first 30 days post-conception. In 4 of 20 cows a significant drop in progesterone concentration was found 15-19 days post-conception. The results indicate that the luteal activity of the 1st post-partum ovarian cycle is inferior to that of the following cycles. There is a significant correlation in the intensity of the luteal activity between cycles. Ovarian cyclicity continues in early pregnancy in, at least, 20% of cows. The sampling frequency is of importance in studies concerning the luteal activity.

Animals↗

PubMed1990

Progesterone and 17 alpha-hydroxyprogesterone. Novel stimulators of calcium influx in human sperm.

Progesterone and 17 alpha-hydroxyprogesterone (but not other steroids such as testosterone, corticosterone, beta-estradiol, estrone, dehydroepiandrosterone, 20 alpha-hydroxypregnen-3-one, androstenedione, and pregnenolone) were shown to cause an immediate increase, in free cytosolic calcium ([Ca2+]i) in both capacitated and noncapacitated human sperm, using the fluorescent indicator fura 2. Significant increases in [Ca2+]i were observed with 10 ng/ml progesterone, while maximum effects were seen with 1 microgram/ml progesterone. Two other steroids 11 beta-hydroxyprogesterone and 5 alpha-pregnane-3,20-dione exhibited significant activity to increase [Ca2+]i. This increase in [Ca2+]i elicited by progesterone was entirely due to Ca2+ influx from the extracellular medium since the increase in [Ca2+]i was blocked by the Ca2+ chelator EGTA (2.5 mM) and the Ca2+ channel antagonist La3+ (0.25 mM) when added to the medium containing 2.5 mM Ca2+. Progesterone also stimulated the uptake of Mn2+ into sperm as measured by the quenching of fura 2 fluorescence. Progesterone has been found in human follicular fluid at levels capable of stimulating increases in [Ca2+]i. The similarities in responses induced by human follicular fluid and progesterone an increase in [Ca2+]i, and hence the acrosome reaction, is progesterone and/or 17 alpha-hydroxyprogesterone. Progesterone (1 microgram/ml) did not increase [Ca2+]i in somatic cells such as adipocytes, hepatocytes, Balb/c 3T3 cells, normal rat kidney, or DDT1 MF-2 cells. The effects of these progestins to increase [Ca2+]i, by activating a receptor-operated calcium channel, is the first report of such an activity in sperm. This phenomena possibly opens up a new field of steroid action in the area of sterility, fertility, and contraception at the level of the sperm.

17-alpha-Hydroxyprogesterone↗