Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Progesterone--indications”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1994

The behavioral component of the ram effect: the influence of ram sexual behavior on the induction of estrus in anovulatory ewes.

The objective of this study was to test whether the sexual behavior of the ram affects the ram effect. Rams exhibiting either high (HP) or low (LP) levels of sexual performance (on the basis of serving capacity tests) were exposed to 89 anestrous ewes for 28 d. Thirty-two anestrous ewes were not exposed to rams. The objective of this study was to compare the efficacy of estrus induction by HP (n = 4) vs LP (n = 4) rams. Plasma progesterone concentration was used as an index of ovarian activity. Groups of ewes were exposed to either an HP or an LP ram in a .32-ha pasture. Courtship behaviors of rams were recorded for 6 h on the initial day of exposure and for 30-min periods on alternate days thereafter. A greater percentage of ewes exposed to HP rams ovulated (95%) compared with ewes exposed to LP rams (78%) (P < .02). On the 1st d of exposure, the HP rams exhibited more courtship behavior and spent more time near the ewes (P < .04). The HP rams spent more time within 1 m of ewes during the 28-d exposure. There were no differences in the amount of contact with rams (LP or HP) between rise in progesterone indicate of ovulation tended to occur earlier (P = .06) in ewes penned with HP rams. A greater percentage of ewes exposed to LP rams (P = .03) had early elevations of progesterone with no concurrent sexual behavior. These data imply that in addition to a pheromone the sexual behavior of the ram may be important in initiating ovarian cycle activity.

Anestrus↗
PubMed2002

Melengestrol acetate blocks the preovulatory surge of luteinizing hormone, the expression of behavioral estrus, and ovulation in beef heifers.

We tested the hypothesis that melengestrol acetate (MGA), an orally active progestin, blocks estrus and the preovulatory surge of luteinizing hormone (LH) in beef heifers. Cycling yearling Angus heifers were divided randomly into two groups: MGA-treated (n = 6) and control (n = 5). All heifers received injections of prostaglandin F2alpha (PGF) on d -25, -11, and 0 to synchronize estrus. Following the last PGF injection on d 0, heifers were fed either 0.5 mg MGA in a carrier or the MGA carrier each day for 8 d. At 4-h intervals on d 1 through 6, all heifers were observed for expression of estrous behavior, and blood samples were collected and assayed for LH. Daily blood samples were collected at 0800 on d 1 through 10 and assayed for circulating progesterone concentrations. All control heifers exhibited estrus and a preovulatory surge of LH. In each case, this was followed by increases in circulating concentrations of progesterone indicative of ovulation and normal luteal function. In contrast, none of the MGA-treated heifers exhibited estrus, LH surges, or evidence of ovulation. The results of this experiment show that MGA prevents ovulation in cattle by inhibiting the preovulatory surge of LH.

Animals↗
PubMed2003

Ovarian cyclicity in thyroid-suppressed ewes treated with propylthiouracil immediately before onset of seasonal anestrus.

Two experiments were conducted to determine if propylthiouracil (PTU)-induced thyroid suppression immediately before onset of anestrus would extend the breeding season in mature ewes. In Exp. 1, twice-weekly serum concentrations of progesterone indicated that all ewes were cyclic before initiation of treatment. Beginning on d 0 (January 17), ewes received 0 (n = 4), 20 (n = 5), or 40 (n = 5) mg of PTU x kg(-1) of body weight (BW) x (-1) for 35 d. Blood samples were collected regularly throughout the trial and serum thyroxine and progesterone were quantified. Ewe BW were similar (P > 0.90) among treatments before the experiment began (mean = 78.2 +/- 4.5 kg). Likewise, serum concentrations of thyroxine averaged 86.5 +/- 8.0 ng/mL on d 0. After 11 d of PTU treatment, serum thyroxine was 90.2,75.2, and 44.2 +/- 14.0 ng/mL in ewes receiving 0, 20, and 40 mg of PTU/kg BW, respectively (linear effect, P = 0.04). On d 20, thyroxine values in the three respective groups were 73.0, 51.1, and 16.1 +/- 12.9 ng/mL (linear effect, P < 0.01). Fourteen days after PTU treatment ended, serum thyroxine did not differ (P = 0.53) among the three respective groups (71.4,73.3, and 57.5 +/- 11.8 ng/mL). Ewes receiving PTU tended to weigh less on d 42 (84.2, 78.2, and 71.8 +/- 5.1 kg for ewes treated with 0, 20, and 40 mg PTU/kg, respectively; linear effect, P = 0.10). Day of onset of anestrus was designated as the day on which serum progesterone decreased and remained below 1 ng/mL. Ewes treated with 0, 20, or 40 mg of PTU/kg BW became anestrous on d 16,40, and 81 (+/- 12) of the experiment, respectively (linear effect, P < 0.01). At the time the 35-d treatment period ended, 25, 60, and 100% of ewes receiving 0, 20, or 40 mg of PTU/kg exhibited normal estrous cycles. In Exp. 2, ewes received 0, 20, or 40 mg of PTU/kg BW for 14 d. The dose was then decreased to 0, 10, and 20 mg of PTU/kg BW for the remaining 21 d. Serum thyroxine decreased to concentrations below 20 ng/mL by d 9 after initiation of PTU treatment. Ewe weights did not differ throughout the trial and no BW loss was observed. The average day that each group entered anestrus was similar to those in Exp 1. Large doses of PTU dramatically lower serum thyroxine and this effect appears to inhibit onset of anestrus in ewes.

Analysis of Variance↗
PubMed1975

Plasma levels of progesterone and oestrogens in women treated with an oral contraceptive of low oestrogen content (Ovostat 1375).

The plasma levels of progesterone and oestrogens were measured during treatment with an oral contraceptive containing 37.5 mug of ethinyl oestradiol and 1 mg of lynestrenol (= 3-desoxy-17alpha-ethinyl-19-nortestosterone) (Ovostat 1375, Organon, Oss, Holland). Blood samples were taken every day during 9 complete cycles in 5 healthy women. The plasma levels of progesterone were in the range of those found during the early follicular phase of the normal women. No ovulation seemed to have occurred. The mean plasma levels of oestrogens (oestradiol and oestrone) during treatment were below those found during early follicular phase of 34 normal cycles although overlapping of values occurred. The ratio between oestradiol and oestrone during treatment was 1:2 vs. 1:1 during the early follicular phase of the normal cycles. In two cycles treatment was started during the midcyclic rise of oestrogens. No rise of progesterone indicating corpus luteum formation was found. Despite the low amount of oestrogen in the drug the ovaries appeared to secrete minimal amounts of sex steroids. The lynestrenol content is likely to be partly responsible for the inhibition of ovulation and the additional suppression of steroidogenesis.

Adult↗
PubMed1987

Proliferative potential and polymorphism of human endometrial stromal cells.

The proliferative potential of stromal cells from human endometrium, separated from glands by dispersion in the presence of collagenase and subsequent passage through a sieve, was evaluated by determining the total number of cell doublings achieved when cells were repeatedly subcultured in a 1:2 split ratio in Ham's F-10 medium containing 10% fetal bovine serum (FBS). Fifty doublings or more (up to 100) were observed in 8 of the 26 specimens (30%) which we examined. This number of doublings is high for cells obtained from adult tissues and may in part reflect the unusually great proliferative capacity of human endometrium when compared to that of other tissues. The shape of the stromal cells depended on the medium in which they were originally cultured. Cells cultured in Ham's F-10 medium containing 10% FBS showed the typical fibroblastic morphology at confluence; they appeared elongated or spindle-shaped and formed monolayers. In contrast, cultures in CMRL-1066 medium in the presence of 10% FBS appeared polygonal or stellate-shaped and also formed monolayers. In about 50% of the cultures in CMRL-1066 medium we observed fibroblast-shaped cells that superficially resembled cells grown in Ham's F-10 medium, but were able to form dome structures. In some cultures the regions of prominent overgrowth were macroscopically visible. Switching media during later passages did not reverse the shape of the cells obtained in CMRL-1066 medium or that of the fibroblast-shaped cells in Ham's F-10 medium, suggesting either that the growth of a subpopulation was favoured early during cellular adaptation to primary culture or that there was a single cell population whose phenotype was determined early in culture and then no longer responded to medium factors. Examination of the cytoskeleton after visualization with rhodamine-labelled phalloidin revealed that the arrangement of the microfilaments corresponded to the cell shape observed in living cells under the phase contrast microscope. Distinct changes in morphology were observed when primary stromal cell cultures in CMRL-1066 medium were exposed to progesterone, indicating that progestins may affect cytoskeletal proteins.

Actin Cytoskeleton↗
PubMed1982

Conversion of progesterone from the adrenal or ovary to deoxycorticosterone in plasma.

The in vivo conversion of progesterone to deoxycorticosterone (DOC) by peripheral 21 hydroxylation was studied in normal men and women. The technique used was to infuse labeled progesterone under steady state conditions and isolate the precursor and product from blood by multiple chromatography steps. DOC was chromatographed as both the steroid and its acetylated derivative. The conversion rate was found to be 1.3 +/- 0.1% in men and women despite differences in the concentration of progesterone during the cycle. Since progesterone was very low in men and women in the follicular phase of the cycle, we conclude that DOC is derived from direct secretion. However, progesterone rises to 1073 +/- 101 ng per dl in the luteal phase and the calculations indicate that DOC increases from 8.3 +/- 0.4 (SE) to 15.6 +/- 1.3 ng per dl. 3/4 of luteal phase DOC is from conversion of progesterone. Acute ACTH increases both progesterone and DOC, and almost all of the DOC in plasma is from direct secretion. However, chronic ACTH excess and adrenal 21 hydroxylase deficiency is associated with a fraction (1/4-1/5) of DOC from progesterone indicating that the peripheral conversion rate is unrelated to the adrenal enzyme defect.

Adrenal Glands↗
PubMed1996

Positively charged self-emulsifying oil formulation for improving oral bioavailability of progesterone.

A self-emulsifying oil formulation (SEOF) comprised of Tween 80, benzyl alcohol (BA), ethyl oleate (EO), and oleylamine (OA), able to produce positively charged submicron emulsions upon aqueous or buffer dilution, was developed and characterized. The positive charge of the formulation was attributed to the localization of the cationic lipid, OA, at the oil/water interface of the diluted SEOFs. Binary phase diagram analysis of the basic lipophilic system showed that the SEOF elicited progressive inverse phase behavior under continuous aqueous phase dilution. At infinite dilution fine submicron o/w emulsions were formed only when BA concentrations did not exceed 50% in the formulation. The self-emulsification process was not markedly affected by the variation in pH over the entire physiological range. The neurotoxic effects observed in acute toxicity studies with the concentrated emulsion containing 3% BA obtained from the dilution of the SEOF vehicle were attributed to the BA since a simple aqueous solution at the same BA dose caused similar adverse effects. However, no toxic effects were noticed when the dose administered was 30 times the potential dose that could probably be administered to humans. Comparative oral bioavailability studies in young female rats using several different liquid dosage forms of progesterone indicated that of those studied, only the positively charged SEOF could be considered a potential effective dosage form for oral administration of progesterone since it elicited the highest and most satisfactory absorption profile.

Animals↗
PubMed1978

Milk progesterone to predict reproductive status in a commercial dairy herd.

Progesterone was measured in milk strippings of cows to evaluate potential diagnosis of pregnancy and to estimate embryonic mortality. Progesterone in milk was measured at 20 days and at 10-day intervals thereafter through 90 days after artificial insemination when the cows were palpated for pregnancy. Mean progesterone for 24 nonpregnant cows in estrus was 4.5 ng/ml at 20 days after insemination. Cows were classified as pregnant or nonpregnant by a formula which provided a progesterone concentration for which the probability of nonpregnancy was .8. At 20 days after insemination, the success in identifying the nonpregnant and pregnant cows was 87% and 67%. Ten of 34 nonpregnant cows with low (nonpregnant range) progesterone in milk on day 20 were not seen in estrus. Progesterone at sampling intervals after 20 days was used to investigate incorrect assessments. Seventeen nonpregnant cows had progesterone indicative of pregnancy at day 20. Progesterone in milk decreased at various later sampling intervals in all 17 cows. Two of these cows were diagnosed as having pathology of their reproductive tracts. If the other 15 cows experienced death of their embryos, the frequency of embryonic mortality was 28%.

Animals↗
PubMed1989

Effect of treatment with progesterone on pregnancy rate and plasma concentrations of progesterone in Holstein cows.

Progesterone-releasing intravaginal devices inserted into the vaginas of dairy cows between d 5 to 12 (n = 28) or d 10 to 17 (n = 27) after insemination increased pregnancy rate to 60 over 30% in untreated control cows (n = 30). Plasma progesterone concentrations were increased during both progesterone treatments. Subtraction of the estimated contribution of exogenous progesterone indicated that endogenous, luteal progesterone was reduced during d 10 to 17 but not during d 5 to 12. Supplemental progesterone increased pregnancy rate but suppressed endogenous production of progesterone when administered during d 10 to 17 after insemination.

Administration, Intravaginal↗
PubMed1997

Progesterone production in vitro by mouse luteal cells: response to follicle-stimulating hormone, luteinizing hormone, and prolactin.

The purpose of this study was to determine the effects of ovine follicle-stimulating hormone (FSH), luteinizing hormone (LH); prolactin, and recombinant FSH and a protein kinase C activator (phorbol 12-myristate 13-acetate [PMA]) on progesterone production by dispersed luteal cells (large + small) from Day 4 pregnant mice. Corpora lutea (CL) were collected on Day 4 of pregnancy (Day 1 = sperm positive smear), and dispersed luteal cells were isolated using collagenase. After overnight incubation, the luteal cells were incubated with or without FSH, LH, prolactin, or recombinant human FSH or PMA for 4 hr or an additional 24 hr at 37 degrees C; media were collected and progesterone was determined by RIA. Ten nanograms and 100 ng of ovine FSH, LH and prolactin were all equally effective in stimulating progesterone synthesis in media recovered after 24 hr of incubation. Moreover, the combination of all three gonadotropins yielded maximum levels of progesterone indicating a luteotrophic complex in vitro, paralleling previous in vivo findings. Recombinant human FSH-devoid of LH contamination-at doses of 10 and 100 ng also significantly stimulated progesterone synthesis, which strongly suggests that FSH has luteotropic activity in the mouse, thus agreeing with our previous in vitro results with CL of the pregnant hamster and rat. One hundred nanomolar PMA by itself did not affect progesterone production but significantly decreased dibutyrl cAMP-, forskolin-, FSH-, and LH-induced progesterone production, suggesting that activation of protein kinase C may block the luteotropic effects of LH and FSH during murine pregnancy.

Animals↗
PubMed2002

Direct and indirect inhibition of Th1 development by progesterone and glucocorticoids.

Progesterone may contribute to the maternal suppression of immunity to the fetus by modulating the Th1/Th2 balance. To clarify whether progesterone directly or indirectly affects T cell differentiation, we used two experimental systems with isolated T cells in vitro. In one system, isolated CD4+CD8+thymocytes differentiated into Th1 and Th2 by two pulse stimulations with defined combinations of ionomycin and PMA followed by the treatment with IL-12, IL-4, and IL-2. In the second system, functional differentiation was induced in purified naive CD4 T cells with cytokines and Abs to CD3 and CD28. In both systems, progesterone added with cytokines suppressed Th1 development at concentrations associated with pregnancy, but enhanced the development of IL-10-producing Th2 cells. Because IL-10 is known to inhibit APC production of IL-12, Th1 development may be also suppressed indirectly by progesterone. However, progesterone failed to enhance IL-10 production in the absence of IL-12. The p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 inhibited Th1 development and enhanced Th2 development, as did progesterone, indicating that p38 MAPK and extracellular signal-regulated kinase pathways are involved in Th1 development. However, the progesterone effects may not be simply due to a modulation of MAPK activities, because the inhibitor did not significantly affect the development of IL-10-producing cells in the presence or absence of progesterone. Glucocorticoids exerted effects similar to those of progesterone on Th1/Th2 development even at lower concentrations. These results suggest that progesterone as well as glucocorticoids directly inhibit Th1 development and enhance Th2 development.

Adjuvants, Immunologic↗
PubMed2002

The pattern of estradiol and progesterone differs in serum and tissue of benign and malignant ovarian tumors.

Epidemiological studies have indicated a relationship between gonadal steroid hormones and ovarian cancer. A production of both estradiol and progesterone by ovarian cancers has been demonstrated. The local steroid concentrations and the putative relation to histopathological and clinical condition were investigated herein. Ovarian tissue, ovarian tumor cyst fluid, ovarian vein samples and peripheral serum concentrations of estradiol and progesterone in pre- and post-menopausal women, subdivided into groups with normal ovaries, benign, borderline and malignant ovarian tumors, were quantitatively assessed. Both ovarian tissue concentrations of estradiol and progesterone were more than 100-fold higher than in serum. Based on differences in concentrations between different ovarian tumor groups, the data is not coherent with the previously suggested increased production of estradiol and progesterone in ovarian cancer tissue, since post-menopausal women with ovarian cancer presented lower median tissue hormone levels, most pronounced between malignant and benign tumors; median (25 and 75 percentile) estradiol; 9.40 (6.67-15.50) vs 16.44 (12.49-23.20), p=0.02 and progesterone; 308 (240-575) vs 957 (553-1143) pmol/g wet weight, p<0.01, n=81. Lower concentrations of estradiol, but not progesterone, were found in ovarian cancer tissue, ovarian cyst fluid and peripheral serum in patients with FIGO stages 3 and 4 than in stages 1 and 2. The novel finding of a large ovarian tissue to serum difference of both estradiol and progesterone indicates an important role of ovarian tissue concentrations in tumor biology and raises the question of adequate doses of anti-hormonal therapy in women with ovarian cancer.

Cyst Fluid↗
PubMed1992

Central nervous system peptide and amino acid modulation of luteinizing hormone and prolactin secretion in the pig.

We recently demonstrated that pulsatile LH secretion is associated with pulsatile gonadotropin releasing hormone (GnRH) in the pig. Endogenous opioid peptide (EOP) inhibition of pulsatile LH and prolactin (PRL) secretion is dependent on reproductive status and development of this EOP system is a brain maturational process independent of the ovary. Once sexual maturation has occurred, EOP then become part of a progesterone dependent system and EOP inhibit a noradrenergic component of this system. During lactation, EOP also inhibit pulsatile LH, but stimulate PRL secretion. N-methyl-d,l-aspartate (NMA), an agonist of the excitatory amino acids (EAA), aspartate and glutamate, suppressed LH secretion in gilts pretreated with progesterone or vehicle. Both the EOP agonist, morphine (MOR), and the EOP antagonist, naloxone (NAL), delayed emergence and time to maximum serum LH concentration of the estradiol-induced LH surge in prepuberal and mature gilts, respectively. Therefore, EOP may normally have both a permissive as well as an inhibitory role in the LH surge mechanism. Although a norepinephrine synthesis inhibitor failed to alter basal PRL secretion, the PRL increase after NAL was suppressed in progesterone-treated ovariectomized (OVX) gilts. NAL suppressed the PRL response to NMA in OVX gilts pretreated with oil vehicle or progesterone, indicating that NMA stimulation of PRL secretion is mediated through the EOP system.

Amino Acids↗
PubMed1985

Effect of primary and recurrent infections bovine rhinotracheitis virus infection on the bovine ovary.

Six heifers were inoculated IV at estrus with the Iowa or Colorado isolates of infectious bovine rhinotracheitis virus (IBRV). Subsequent measurements of plasma progesterone indicated that corpus luteum function was depressed in all heifers. In the 1st estrous cycle after inoculation, progesterone values did not exceed 2 ng/ml in 3 heifers given the Iowa isolate. Although maximal progesterone values were greater than or equal to 2 ng/ml in 3 heifers given the Colorado isolate, values were lower than those in later cycles. Five heifers had maximal diestrual progesterone values greater than or equal to 5 ng/ml within 5 weeks after inoculation, but in the 6th heifer, this amount of progesterone was not present until 8 weeks after inoculation. Three to 5 months after inoculation, all heifers were given 5 daily injections of dexamethasone, 2 heifers each during metestrus, diestrus, or proestrus. Subsequent recrudescence of IBRV was demonstrated in all heifers by the isolation of virus from vaginal or nasal swab samples. The heifers were killed 10 to 17 days after initiation of dexamethasone treatment and their reproductive organs were examined for lesions and IBRV. Lesions were not seen, and IBRV was isolated only from the corpus luteum of a heifer given dexamethasone during diestrus.

Animals↗
PubMed1982

Lectins, calcium ionophore A23187 and peanut oil as deciduogenic agents in the uterus of pseudopregnant mice: effects of tranylcypromine, indomethacin, iproniazid and propranolol.

Intraluminal injections of lectins, including concanavalin A (Con A), wheatgerm lectin, and soybean lectin, Con A-Sepharose 4B beads, calcium ionophore A23187 or peanut oil into the left uterine horns of mice on day 4 of pseudopregnancy induced the formation of deciduomata and significantly increased the weight and alkaline phosphatase activity of uterine tissue on day 7 of pseudopregnancy. In contrast, injections of these materials into the uterine horns of non-pseudopregnant mice that had not been previously mated failed to induce similar responses. Tranylcypromine blocked the decidual cell reaction artificially induced by lectins, calcium ionophore A23187 and peanut oil in pseudopregnant mice. However, uterine responses observed after individual and concurrent injections with indomethacin, iproniazid, propranolol or progesterone indicated that this deciduoma-blocking effect may not be solely related to the ability of tranylcypromine to inhibit prostacyclin biosynthesis but may also involve catecholamines and luteolytic prostaglandins which interfere with decidualization on day 4 and day 6 of pseudopregnancy, respectively. A role for prostaglandins and uterine beta-adrenergic receptors, however, was implicated in the induction of decidualization because both indomethacin and propranolol blocked the response to peanut oil. The results suggested that the embryonic signal responsible for the induction of the decidual cell reaction in mice may involve surface interactions between the embryo and uterine luminal epithelium resulting in a stimulation of the uterus via glycoprotein receptors. A role for calcium was implicated in this phenomenon.

Animals↗
PubMed1983

Antibody-recognized [125I]estradiol-receptor complex in ovarian epithelial carcinoma.

Monoclonal antibody against human breast cancer estrogen receptor was used to demonstrate binding of a gamma- and Auger electron-emitting estrogen to the estrogen receptor in ovarian epithelial carcinomas. When cytosols of estrogen receptor-rich ovarian adenocarcinomas were analyzed on sucrose gradients containing 0.4 M KCl, the presence of monoclonal antibody against breast cancer estrogen receptor caused a binding peak for [125I]- and [3H]estradiol to shift from the 4S to the 8-9S region, indicating antibody complex formation with ovarian adenocarcinoma estrogen receptor. The antibody-shifted peak of 8-9S [125I]- and [3H]estradiol binding was totally inhibited by a 100-fold molar excess of diethylstilbestrol (DES), but not by testosterone or progesterone, indicating a preference for estrogen binding by the antibody-shifted estrogen receptor. When estrogen receptor from the nuclear fraction of ovarian adenocarcinomas was incubated with [125I]estradiol at 1C, in the presence of 0.4 M NaSCN to facilitate exchange with endogenous ligand, binding occurred that was inhibitable by DES and restricted to the 4S region. Under these conditions the nuclear estrogen receptor was also shifted to the 8-9S region by the presence of the monoclonal antibody against estrogen receptor.

Adenocarcinoma↗
PubMed1993

Control of luteal function in the mink (Mustela vison).

The ranch mink was studied to determine the role of pituitary luteotrophins on corpus luteum (CL) function before and after implantation. Twelve mink were treated with monoclonal antiserum against gonadotrophin-releasing hormone (GnRH), and 12 with an irrelevant monoclonal antibody during embryonic diapause. Activation of the CL, plasma progesterone concentration and embryo implantation were unaffected by this treatment. In a second trial, groups of ten mink were treated with GnRH antibodies, bromocriptine, bromocriptine plus 0.5 mg prolactin per day per animal, or ethanol vehicle. Comparison of the consequent profiles of progesterone indicated that both bromocriptine and anti-GnRH compromised postimplantation CL function by inducing regression of the corpus luteum. Incubation of dissociated luteal cells from ovaries of mink at 21-24 days after implantation with either LH or prolactin increased the accumulation of progesterone over 2 h. Addition of 25-hydroxy-cholesterol (25OHC) as substrate increased basal levels and the progesterone accumulation stimulated by LH and prolactin; the increases induced by luteotrophins were additive. There was an apparent synergistic interaction between prolactin and canine low-density lipoproteins (LDL) in the stimulation of progesterone secretion in vitro. The results are interpreted to indicate that LH/FSH are not required for luteal support during embryonic diapause, or for luteal activation. Prolactin is necessary for luteal activation, and LH and/or FSH and prolactin are obligate luteotrophins during the postimplantation period in the mink.

Animals↗