Metabolism of progesterone by preimplantation mouse blastocysts in culture

This study examined the question whether or not preimplantation mouse blastocysts can metabolize progesterone (P). When young (Day 4) and implanting (Day 5) blastocysts were cultured in supplemented Eagle's minimum essential medium containing 0.4 microM [3H]P, metabolism of P and formation of metabolites were noticed at 10 h of culture. The metabolites accumulated in medium as the culture continued to 118 h. Three of the four metabolite fractions were identified, by crystallization to constant sp. act., to be 5 alpha-pregnane-3,20-dione and 3 beta-hydroxy-5 alpha-pregnan-20-one (or allopregnanolone), accounting for 22 and 57% of radioactivity, respectively, and a small amount (1-10%) of 3 alpha-hydroxy-5 alpha-pregnan-20-one. This suggests that both delta 4-5 alpha-reductase and 3 alpha- and 3 beta-hydroxysteroid dehydrogenase are active. Day 5 blastocysts were much more active than Day 4 blastocysts in P metabolism. It is suggested that the ability of blastocysts to metabolize P could produce the following effects in the adjacent endometrium: a lessening of P effects; and consequently a change in P-estrogen interaction; and possible effects from the metabolites. These local effects of embryos on the endometrium may be important for embryonic development and implantation.     

Changing 17 beta-hydroxysteroid dehydrogenase activity in preimplantation rat and mouse embryos

The 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity in rat and mouse preimplantation embryos was determined by measuring the interconversion of estradiol (E2) and estrone (E1). Rat and mouse embryos were cultured in medium containing 450 nM [3H]E1 or -E2 and the amount of [3H]E1 and -E2 in the medium at the end of the first hour was determined. The results showed that in both species 17 beta-HSD activity was detectable from the one-cell stage (Day 1) onward. In the rat, 17 beta-HSD effected primarily E2----E1 conversion, with the activity decreasing from Day 1 to Day 5. In the mouse, we found primarily E1----E2 conversion from Day 1 to the morning of Day 4, then E2----E1 increased sharply to near the E1----E2 rate in the evening of Day 4 and surpassed the E1----E2 rate the next morning. It seems that: 1) 17 beta-HSD is active throughout the entire preimplantation period, and 2) the enzyme activity changes during preimplantation development. Thus, the rat and mouse preimplantation embryo could regulate the E1- to -E2 ratio in the embryos and in their environment.     

Uterine progesterone metabolism during early pseudopregnancy in the rat

We measured uptake and metabolism of progesterone (P4) during the estrous cycle and Days 2-6 of pseudopregnancy (PSP) to determine uterine P4 dynamics during preimplantation. Rats were infused with [3H]P4 for 60 min, blood was obtained, the uterus was removed, and endometrium and myometrium were isolated. Tissue radiolabeled P4 and P4 metabolites (5 alpha-pregnane-3,20-dione, DHP; 20 alpha-hydroxy P4; 17 alpha-hydroxy P4, and hydroxylated DHP derivatives) were extracted and separated by thin-layer chromatography (TLC). Serum P4 was measured by radioimmunoassay (RIA) in another group of rats. Endometrial and myometrial concentrations of [3H]P4 were greater (p less than 0.05) than plasma values. In contrast, [3H]DHP levels in the endometrium were higher (p less than 0.01) than values in myometrium or plasma. Compared to values in the estrous cycle, endometrial ratios of [3H]DHP/[3H]P4 and [3H]metabolites/[3H]P4 decreased (p less than 0.02) on Days 3-5 of PSP. Serum P4 levels during the estrous cycle (13-25 ng/ml) increased (p less than 0.01) to 120 ng/ml on Days 3-5 of PSP. Estimated concentration of P4 in the endometrium during the estrous cycle (90 ng/g) increased (p less than 0.05) to 580 ng/g by Day 5 of PSP. Similar observations were noted for the estimated endometrial concentrations of DHP and all P4 metabolites. We suggest that both endometrium and myometrium take up and metabolize P4 during the estrous cycle and early PSP. However, endometrial P4 metabolism during PSP is greater than during the estrous cycle, in part because of increased ovarian secretion and endometrial concentration of P4.(ABSTRACT TRUNCATED AT 250 WORDS)     

Steroid 5 alpha-reductase activity in endothelial cells from human umbilical cord vessels

The metabolism of radiolabeled progesterone and androstenedione was evaluated in endothelial cells from human umbilical cord vein and arteries maintained in culture. The predominant metabolite of progesterone was 5 alpha-pregnane-3,20-dione and that of androstenedione was 5 alpha-androstane-3,17-dione. Thus, the major pathway of progesterone and androstenedione metabolism within these cells is via steroid 5 alpha-reductase. The rate of formation of 5 alpha-pregnane-3,20-dione from progesterone by venous endothelial cells was linear with incubation time up to 4 h and with cell number up to 1.6 X 10(6) cells/ml. The apparent Km of 5 alpha-reductase for progesterone was 0.4 microM; and, the Vmax was 55 pmol 5 alpha-pregnane-3,20-dione formed/mg protein X h. The rate of 5 alpha-androstane-3,17-dione formation from androstenedione also was linear with incubation time up to 4 h. In addition to 5 alpha-androstane-3,17-dione, the metabolism of androstenedione by either venous or arterial cells resulted in the formation of various minor metabolites, including testosterone and 5 alpha-reduced steroids, viz. 5 alpha-dihydrotestosterone, androsterone, isoandrosterone, 5 alpha-androstane-3 alpha, 17 beta-diol, and 5 alpha-androstane-3 beta, 17 beta-diol. Estrogens (i.e. estradiol-17 beta and estrone) were not detected as products of androstenedione metabolism. The formation of these metabolites are indicative that the steroid-metabolizing enzymes present in endothelial cells are: 5 alpha-reductase, 17 beta-hydroxysteroid oxidoreductase, 3 alpha-hydroxysteroid oxidoreductase, and 3 beta-hydroxysteroid oxidoreductase.     

Binding of epidermal growth factor and transforming growth factor-alpha in mammalian preimplantation embryos

Preimplantation embryos of the pig (Days 11 to 15), cow (Days 14 to 16), sheep (Day 14) and pony (Day 16) bind epidermal growth factor (EGF) specifically. Binding was not detected in embryos of the rabbit at Day 5 or 6 or the hamster at Day 3. Transforming growth factor-alpha displaced [(125)I] EGF in pig, cow and pony embryos almost as much as unlabeled EGF. The binding affinities of EGF ranged from 12 to 233 pM in pig and cow embryos. The range of species and binding features indicate that the EGF family may play a significant role in mammalian preimplantation development.     

Steroid metabolism by rat nasal mucosa: studies on progesterone and testosterone

The metabolism of [4-14C]progesterone and [4-14C]testosterone by slices of the nasal mucosa from rats was studied. As shown by gas chromatography-mass spectrometry there was a preferential formation of reduced progesterone-metabolites (5 alpha-pregnane-3,20-dione, 3 alpha- and 3 beta-hydroxy-5 alpha-pregnane-20-one, 20 alpha- and 20 beta-hydroxypregn-4-en-3-one, 2 alpha,3 alpha-dihydroxy-5 alpha-pregnane-20-one, 3 alpha,16 alpha-dihydroxy-5 alpha-pregnane-20-one) and reduced testosterone-metabolites (4-androstene-3,17-dione, 5 alpha-dihydrotestosterone, 3 alpha-hydroxy-5 alpha-androstane-17-one, and 5 alpha-androstane-3 alpha, 17 beta-diol, 2 alpha-hydroxy-5 alpha-dihydrotestosterone, 5 alpha-androstane-2 alpha,3 alpha, 17 beta-triol) indicating the presence of 5 alpha-reductase, 3 alpha-, 3 beta-, 17 beta-, 20 alpha- and 20 beta-hydroxysteroid oxidoreductase activities in this tissue. Progesterone-metabolites hydroxylated at positions 2 alpha, 6 alpha, 6 beta, 15 alpha and 16 alpha and testosterone-metabolites hydroxylated at positions 1 beta, 2 alpha, 6 beta, 15 beta and 16 alpha were also identified, indicating the presence of several steroid hydroxylases in the nasal mucosa. Autoradiography of the nasal region of rats injected with [4-14C]progesterone or [4-14C]testosterone showed a selective localization of radioactivity in the mucosa covering the olfactory region of the nasal cavity.     

Substrate-binding ability of Escherichia coli ribonucleic acid polymerase in relation to its protein composition.

The metabolism of [3H]progesterone in the rabbit endometrium and myometrium was studied in vitro. The major metabolities identified were 5alpha-pregnane-3,20-dione, 20alpha-hydroxypregn-4-en-3-one, 3beta-hydroxy-5alpha-preganan-20-one and 5alpha-pregnane-3beta,20alpha-diol. Other minor metabolites tentatively identified were 3alpha-hydroxy-5beta-pregnan-20-one,20alpha-hydroxy-5beta-pregnan-3-one and 5beta-pregnane-3alpha,20alpha-diol. The ability of the endometrium to metabolize progesterone on a unit weight bais was about 2.7 times that of the myometrium. The metabolism of [3H]progesterone in the rabbit uterus under the influnce of oestradiol-17beta and progesterone was studied. The ability of the oestradiol-treated rabbit uterus to metabolize progesterone was increased to 3.47 times that of the overiectomized control uterus, whereas the oestradiol-progesterone-treated rabbit uterus metabolized only 1.86 times that of the control. Study of the metabolism of progesterone with uterine subcellular preparations revealed that the 5alpha-reductase enzyme was present mainly in the nuclear fraction; 20alpha-hydroxysteroid dehydrogenase was found in the cytosol fraction and 3beta-hydroxysteroid dehydrogenase in the particulate fraction of the uterus. The metabolic pathways of progesterone in the rabbit uterine tissue are discussed.     

Possible function of 17 beta-hydroxysteroid dehydrogenase in preimplantation hamster embryos

17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) catalyzes the interconversion of estradiol-17 beta (E2) and estrone (E1). The present study is designed to investigate the following: (1) the developmental stage of hamster embryos at which 17 beta-HSD activity first becomes detectable, and (2) the E1----E2 and E2----E1 conversion rate in the preimplantation hamster embryo. Embryos obtained from superovulated hamsters on days 1-4 were cultured in medium containing 107 ng [3H]E1 or -E2/ml and the respective conversion product, [3H]E2 or -E1, was isolated and assayed. The results show that (1) E1----E2 conversion was active in all embryos at the rate of 0.57, 0.66, 0.54 and 0.48 fmol/embryo/hr for day 1 (one-cell), 2 (two-cell), 3 (eight-cell) and 4 (blastocyst), respectively, and (2) E2----E1 conversion was not detectable in hamster embryos. In long-term blastocyst culture, E2----E1 conversion becomes detectable at 25 hours and increases sharply from 25 to 47 hours. These results suggest that (1) 17 beta-HSD may function mainly to convert E1 into E2 in preimplantation hamster embryos and (2) E2----E1 conversion may become active only during and after implantation.     

Secretion of pregnane compounds from polycystic ovaries of androgen-sterilized rats

Progesterone, 5 alpha-pregnane-3,20-dione (5 alpha-DHP), 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha-OH), 20 alpha-hydroxy-4-pregnen-3-one (20 alpha-DHP), 20 alpha-hydroxy-5 alpha-pregnan-3-one, and 5 alpha-pregnane-3 alpha, 20 alpha-diol in ovarian venous plasma of androgen-sterilized rats treated with 25 IU of human chorionic gonadotropin (hCG) were assayed by gas chromatography. The compounds listed were essentially undetectable in polycystic ovaries of the androgen-sterilized rats. However, after injection of hCG, levels of these steroids were high. Levels of progesterone and 5 alpha-pregnane compounds reached a peak within 1 or 2 days after hCG treatment and then fell slowly. The level of 20 alpha-DHP reached a peak on day 4 after hCG treatment and remained high thereafter. Injection of 2 micrograms of luteinizing hormone (LH) before sample collection increased the secretion of progesterone at all times tested except when it was already at a peak. The secretion of 5 alpha-DHP and 3 alpha-OH was also increased by LH after hCG treatment, but the ability of the ovary to produce these steroids was not, suggesting that there was low 5 alpha-reductase activity in the cystic ovary before hCG treatment. The results suggest that ovulation and luteinization in cystic follicles may cause the low activities of 5 alpha-reductase and 20 alpha-hydroxysteroid dehydrogenase in polycystic ovaries of androgen-sterilized rats to increase.     

Further studies on in vitro steroidogenesis by luteal cells from long-term hypophysectomized rats

Immature pregnant mare's serum gonadotropin-treated rats were hypophysectomized on the day of ovulation (Day 1 of luteal function), and luteal steroidogenesis and human chorionic gonadotropin (hCG) and prolactin (Prl) binding sites were determined on Days 5, 10, 20 and 30 (H5- H30 ) compared with intact rats on Days 5 or 10 (C5 or C10). On H5, dispersed luteal cells secreted large amounts of progesterone (P), 20 alpha-dihydroprogesterone (20 alpha-DHP), 17 alpha-hydroxyprogesterone (17 alpha-OHP), and small amounts of testosterone (T) and estradiol-17 beta (E2), but between H10 and H30 , reduced levels of all steroids were produced except for 20 alpha-DHP. Addition of large amount of pregnenolone (P5) or P (100-1000 ng) to dispersed luteal cells increased production of P and 20 alpha-DHP in C5 and H5 rats. The higher serum levels and basal in vitro production of 20 alpha-DHP from H5 to H30 indicates that 20 alpha-oxidoreductase persists in the corpora lutea (CL) at high levels and that 3 beta-ol-dehydrogenase is also present but with P rapidly shunted into its principal metabolite. From H5 to H30 , addition of 10 ng P to luteal cells increased the production of 17 alpha-OHP and addition of 10 ng androstenedione (A) or T enhanced production of T and E2, indicating that 17 alpha-oxidoreductase, 17 beta-hydroxysteroid dehydrogenase and aromatase also persist in the CL. In vitro addition of 10 ng LH significantly stimulated production of P from luteal cells on C5 and H5, whereas on C10 and H10, 100 ng LH was required and on H20 and H30 , 1 microgram LH produced a minimal increase in P.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative changes in the metabolism of 20alpha-hydroxy-4-pregnen-3-one by rat hypothalamus and pituitary during proestrus.

The in vitro conversion of 20alpha-hydroxy-4-pregnen-3-one (20alpha-DHP) by medial basal hypothalamus and anterior pituitary was investigated throughout the day of proestrus in the 4-day cyclic rat. Reverse isotopic dilution analysis was utilized to quantitate the substrate remaining and three metabolic products: 20alpha-hydroxy-5alpha-pregnan-3-one, 5alpha-pregnane-3alpha,20alpha-diol and progesterone. Serum levels of 20alpha-DHP, progesterone, LH and FSH were measured by radioimmunoassay. Conversion of 20alpha-DHP to its 5alpha-reduced metabolites (20alpha-hydroxy-5alpha-pregnan-3-one and 5alpha-pregnane-3alpha,20alpha-diol) by the pituitary was constant throughout proestrus except for a significant decrease at 1600 h, near the end of the critical period. Although 5alpha-reduction of 20alpha-DHP by the hypothalamus fluctuated, it was relatively high at 1600 h and was lowest at 1400 h. Small amounts of progesterone (less than2%) were formed but there was not variation with time. The decrease in pituitary enzymic activity coincided with the time when serum levels of LH, FSH and progesterone were increasing but not with later times when the elevated serum levels were maintained. Thus, there may be endogenous regulation of 5alpha-reductase and 3alpha-hydroxysteroid dehydrogenase activity in rat pituitary and perhaps hypothalamus on the afternoon of proestrus. The regulation and subsequent effects of quantitative changes in 5alpha-reduction of 20alpha-DHP by pituitary and hypothalamus remain to be elucidated.     

Changes in the blood concentrations of progesterone and 20 alpha-hydroxypregn-4-en-3-one during late pregnancy in the conscious rat: a specific role for metabolic clearance rate

Near term in the rat, the blood concentration of progesterone falls while that of 20 alpha-hydroxypregn-4-en-3-one (20 alpha-DHP) increases. This is generally attributed to changes in ovarian secretion alone, but altered rates of hormone metabolism could also have a role. In the present study, therefore, metabolic clearance rate (MCR), production rate, and peripheral interconversion of progesterone and 20 alpha-DHP were measured on Day 16 of pregnancy, the time of maximal progesterone secretion, and on Day 22, one day prior to parturition. Conscious rats (n = 8 per group) were infused with either [3H]progesterone or [3H]20 alpha-DHP and the dynamics of progestin metabolism were calculated from the resultant isotopic and endogenous progesterone and 20 alpha-DHP concentrations. The blood concentration of progesterone declined by 69% between Day 16 (54 +/- 2 ng/ml) and Day 22 (17 +/- 2 ng/ml), and this was due to the combined effect of a 48% increase in the MCR and a 54% decrease in production rate of progesterone. In contrast, the production rate of 20 alpha-DHP was twofold greater on Day 22 compared to Day 16. As a result, the blood concentration of 20 alpha-DHP increased from 28 +/- 3 ng/ml on Day 16 to 40 +/- 6 ng/ml on Day 22, and this change would have been greater but for a concomitant increase (41%) in the MCR of 20 alpha-DHP. Although peripheral conversion of progesterone to 20 alpha-DHP was similar on Day 16 (transfer constant, 12.8 +/- 0.6%) and Day 22 (12.3 +/- 0.9%), the contribution of this conversion to total 20 alpha-DHP production fell from 32% to 7% between the two days.(ABSTRACT TRUNCATED AT 250 WORDS)     

昆明小鼠体内发育早期胚胎葡萄糖代谢关键酶转录产物的分析

首次报道了昆明小鼠体内发育的早期胚胎1-细胞至桑椹期阶段葡萄糖代谢的3种关键酶-6-磷酸葡萄糖脱氢酶（G6PDH）、6-磷酸果糖激酶（PFK）和磷酸葡萄糖变位酶（PGM）的基因转录情况,其分别体现了磷酸戊糖、糖酵解、糖原的合成和分解等途径,根据G6PDH、PFK、PGM的cDNA序列分别设计和合成3套共6对内、外引物,采用巢式RT-PCR方法对其进行检测。结果表明：早期胚胎1-8细胞阶段均有G6PDH基因的转录,叠椹期胚胎不存在该基因的转录,说明早期胚胎1-8细胞阶段可能存在磷酸戊糖,而桑椹期则不存在;1-细胞至桑椹期均存在PFK基因的转录,说明该阶段的胚胎可能存在糖酵解代谢途径;1-细胞至桑椹期均不存在PGM基因的转录,说明该阶段的胚胎可能不存在糖原的合成与分解代谢途径。     

Steroid metabolism in the corpus luteum of the ferret

Implantation in the ferret is believed to be induced by a luteal substance which acts in concert with progesterone (P4) and which is secreted sometime between Days 6 and 8 of pregnancy. This experiment was designed to identify the steroid products synthesized by ferret corpora lutea (CL) on these 2 days of pregnancy. CL were dissected from ferrets on Day 6 or 8 of pregnancy and incubated with [3H] pregnenolone (P3), [3H] P4, or [3H] dehydroepiandrosterone (DHEA). Controls with no tissue or with 50 microliters packed blood cells were incubated at the same time. After incubation of Day 6 CL with [3H] P3 for 180 min, 39% of the added label was found incorporated into P4, 3% into 17 alpha-hydroxyprogesterone (17 alpha-OHP4) and 1% into androstenedione (A). Incubation of Day 8 CL with the same precursor resulted in 35%, 1% and 0.65% of the label being incorporated into the previously mentioned products, respectively. Incubations of Days 6 and 8 ferret CL with [3H] P4 or [3H] DHEA confirmed these results, demonstrating activity of C21-steroid, 17 alpha-hydroxylase and delta 5-isomerase, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD). These results suggest that ferret CL primarily accumulate steroids of the delta4 pathway on both Days 6 and 8 of pregnancy, with P4, 17 alpha-OHP4, A and testosterone (T) being the most abundant products after in vitro incubation. Thus, ferret CL appear to metabolize steroids in a manner similar to that observed in rats, sows and mares.     

Effect of abdominal vagotomy of the pregnant rat on LH and progesterone concentrations and fetal resorption

Abdominal vagotomy on Day 8 of pregnancy in rats decreased the number of live fetuses at Day 16 and increased the number of resorbing fetuses. The activity of delta5-3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the corpus luteum and interstitial gland, LH and progesterone values in plasma and progesterone values in ovarian tissue were all lower in vagotomized rats than in sham-operated controls. Ovarian PGF levels were not affected. We suggest that these effects were caused by a direct effect of vagotomy on LH secretion which in turn lowers 3beta-HSD activity and progesterone levels in ovarian tissue and plasma, leading to fetal resorption.     

11beta-hydroxysteroid dehydrogenase 2 activity is elevated in severe obesity and negatively associated with insulin sensitivity

Alterations in glucocorticoid (GC) metabolism may contribute to the development of obesity and insulin resistance. We aimed to study the role of 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) in human adiposity, paying special attention to the association between altered GC metabolism and insulin sensitivity. In 24-h urine samples of 72 extremely obese (mean BMI 45.5 +/- 1.1 kg/m(2)), but otherwise healthy patients urinary free cortisol (UFF), urinary free cortisone (UFE), tetrahydrocortisol (THF), 5alpha-tetrahydrocortisol (5alpha-THF), and tetrahydrocortisone (THE) were quantified by radioimmunoassay. The sum of the three major tetrahydrometabolites is an estimate for daily GC secretion, and the sum of UFF and UFE represents potentially bioactive-free-GCs. Thirty healthy lean subjects (BMI 22.3 +/- 0.3 kg/m(2)) served as controls. In obese subjects, absolute daily GC secretion and the potentially bioactive-free-GCs were significantly (P < 0.005) higher than in lean controls (11.8 +/- 0.7 vs. 8.0 +/- 0.6 mg/d; and 171.8 +/- 11.2 vs. 117.6 +/- 9.2 mug/d, respectively). However, when these values were corrected for body surface area (BSA), significant differences were no longer detectable. While enzyme activity indices for 5alpha-reductase and 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) were similar in lean and obese subjects, 11beta-HSD2 was markedly elevated in adiposity (3.7 +/- 0.2 vs. 2.1 +/- 0.1; P < 0.0001). This increase was accompanied by a significant reduction in UFF excretion corrected for BSA (16.5 +/- 1.2 vs. 21.7 +/- 2.0 mug/d/m(2); P = 0.0222). Besides, 11beta-HSD2 activity was significantly correlated with insulin sensitivity (P = 0.0262). When body size is accounted for, both adrenal GC secretion and potentially bioactive-free-GCs are indistinguishable between lean and extremely obese subjects. However in obesity, the kidney appears to intensify its supply of the direct substrate cortisone for extrarenal 11beta-HSD1, which may fuel visceral adiposity and insulin resistance.     

Luteotrophic effect, growth and survival of whole versus half embryos and, their relationship with plasma progesterone concentrations of recipient dairy heifers

This prospective and randomised experiment was designed to compare the luteotrophic effect of whole versus half embryos and, to evaluate the relationship between the plasma progesterone (P4) profiles and the rates of early embryonic (from Days 7 to 25), late embryonic (Days 25-42) and foetal (Days 42-63) mortalities of whole and half embryo recipients. Within a single herd, 188 virgin, healthy, cyclic, reproductively sound, with adequate body condition score, Holstein dairy heifers were randomly allocated to receive one whole or one half embryo on Day 7 of the oestrous cycle (Day 0=estrus). In each embryo-transfer (ET) group, half of the recipients were treated with a CIDR (controlled internal drug releasing device) between Days 7 and 19. Pregnancy was evaluated by ultrasound on Days 25, 42 and 63 and plasma P4 profiles were obtained until Day 63 of pregnancy. CIDR-treated and untreated heifers had similar pregnancy rates on Days 25, 42 and 63 and, embryo size on Day 42 was also similar in treated and untreated recipients. Therefore, CIDR treatment failed to promote growth and survival of half and whole embryos. Half embryos presented a significantly higher rate of early and late embryonic mortality than whole embryos. In contrast, foetal mortality was similar in whole and half embryos and, this was coincidental to a similar embryo size on Day 42. Therefore, half embryos exhibited a compensatory growth until Day 42, irrespective of CIDR treatment, after which they presented a similar survival rate to that of whole embryos. Half embryo-derived pregnancies presented significantly lower plasma P4 concentrations on Day 25 than whole embryo-derived pregnancies, suggesting that this lower luteotrophic effect of half embryos could be related to their higher rate of late embryonic mortality. No significant relationship between the early luteal P4 concentrations and embryo survival was observed in whole and half embryo recipients. The first detectable luteotrophic effect of embryonic origin was observed on Day 14 and no detectable second luteotrophic effect was observed until Day 63 of pregnancy. Treatment with CIDR significantly increased plasma P4 concentrations during treatment but induced a significant decrease after removal of the device, suggesting that secretion of luteotropins was downregulated in the course of treatment.     

Androgen metabolism and actions in rat ventral prostate epithelial and stromal cell cultures

The rat ventral prostate requires androgens for normal development, growth, and function. To investigate the relationship between androgen metabolism and its effects in the prostate and to examine differences between the epithelial and stromal cells, we have established a system of primary cell cultures of immature rat ventral prostate cells. Cultures of both cell types after reaching confluency (6-7 days) actively metabolized 3H-labelled testosterone (T), 5 alpha-dihydrotestosterone (5 alpha-DHT), 5 alpha-androstane-3 alpha,17 beta-diol, and 5 alpha-androstane-3 beta,17 beta-diol. The epithelial cells actively reduced T to 5 alpha-DHT and formed significant amounts of 5 alpha-androstane-3,17-dione from T, 5 alpha-DHT, and 5 alpha-androstane-3 alpha,17 beta-diol. All substrates were converted to significant amounts of C19O3 metabolites. The stromal cells also metabolized all substrates, but very little 5 alpha-androstane-3,17-dione was formed. The metabolism studies indicate that both cell types have delta 4-5 alpha-reductase, 3 alpha- and 3 beta-hydroxysteroid oxidoreductase and hydroxylase activities. The epithelial cells have significant 17 beta-hydroxysteroid oxidoreductase activity. The epithelial cells cultures grown in the presence of T have higher acid phosphatase (AP) contents (demonstrated histochemically and by biochemical assay). Tartrate inhibition studies indicate that the epithelial cells grown in the presence of T are making secretory AP. Stromal cell AP is not influenced by T. The results indicate that the cultured cells maintain differentiated prostatic functions: ability to metabolize androgens and, in the case of the epithelial cells, synthesize secretory AP.     

Luteotrophic influence of early bovine embryos and the relationship between plasma progesterone concentrations and embryo survival

This study was carried out to evaluate the luteotrophic influence of early (before Day 7 as well as after Day 7; Day 0=estrus) bovine embryos and the relationship between plasma progesterone (P4) concentrations and embryo survival. Virgin Holstein dairy heifers (n=325) from a single herd were randomly allocated to be nonbred, bred by artificial insemination (AI) or by embryo transfer (ET). Bred heifers were either treated with 1500 IU human chorionic gonadotrophin (hCG) on Day 7 of the estrous cycle or received no hCG treatment. Plasma P4 concentrations on Days 0, 5, 7, 10, 13, 15, 17, 19 and 21 were similar in pregnant AI- and ET-bred heifers and, this was observed in both hCG-treated and untreated females. Nonbred, AI- and ET-bred nonpregnant heifers (both hCG-treated and untreated) presented similar plasma P4 concentrations. Plasma P4 concentrations of pregnant heifers significantly deviated from those of nonpregnant and nonbred heifers on Day 17. In hCG-treated heifers, plasma P4 concentrations and Day 28 pregnancy rate were significantly higher in females with an induced accessory corpus luteum (CL) than in those females without an induced accessory CL. Treatment with hCG, although inducing the formation of accessory CL and significantly increasing plasma P4 concentrations had no significant effect on Day 28 pregnancy rate. In conclusion, this study does not support the existence of any peripherally detectable luteotrophic influence from early embryos (Days 5-7). Plasma P4 was only significantly related to embryo survival on Day 17, the time of expected onset of luteolysis.     

Histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases in hamster trophoblast.

The histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases was demonstrated in hamster trophoblast between Days 8 and 15 of pregnancy. The delta5-3beta-hydroxysteroid dehydrogenase activity in the ectoplacental trophoblast of 8-day embryos was demonstrated by use of delta5-pregnenolone and dehydroepiandrosterone as substrates; between Days 11 and 15, activity was demonstrated in the trophoblastic giant cells of the placenta and in the intra-arterial trophoblast cells when delta5-pregnenolone was the substrate. Between Days 11 and 15, 17beta-hydroxysteroid activity was present in the spongiotrophoblast, labyrinth, placental giant cells and intra-arterial trophoblast cells, as shown by use of testosterone and oestradiol as substrates. Both enzymes were demonstrated in ectopic trophoblast cells, indicating that these activities are autonomous.