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L Ogren

Publications and source records attributed to L Ogren.

At least 37 records · Page 2Linked to original sources
PubMed1989

Recombinant mouse placental lactogen-I binds to lactogen receptors in mouse liver and ovary: partial characterization of the ovarian receptor.

The binding of recombinant mouse placental lactogen-I (mPL-Ir) to liver and ovarian membranes was investigated in virgin and pregnant mice. Competitive binding assays demonstrated that mPL-Ir, mouse placental lactogen-II (mPL-II), and mouse PRL (mPRL) bind to the same receptors in ovarian membranes. The relative abilities of the three hormones to displace [125I]iodo-mPL-Ir from the ovarian lactogen receptors was mPL-II greater than mPL-Ir much greater than mPRL. Scatchard analysis of mPL-Ir binding to ovarian membranes from day 10 pregnant mice showed a Ka of 2.0 x 10(9) M-1 and a binding capacity of 3.2 x 10(-14) mol/mg membrane protein. The specific binding of [125I]iodo-mPL-Ir to ovarian membrane preparations was significantly higher on day 17 than on day 10 of gestation. Dissociation of endogenous hormones with 4 M MgCl2 increased the binding of [125I]iodo-mPL-Ir to ovarian membranes but not to liver membranes. Affinity cross-linking of [125I]iodo-mPL-Ir to liver and ovarian membranes resulted in the specific labeling of proteins with receptor mol wt (Mr) of 44K and 40K (nonreduced) and 50K and 42K (reduced), as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The lactogen receptors from liver and ovary appeared structurally homologous, producing fragments with similar Mr when treated with proteolytic enzymes and undergoing similar reductions in Mr when treated with glycolytic enzymes. The ability of mPLs to bind specifically and with high affinity to receptors in mouse ovarian membranes suggests that these hormones may regulate ovarian function during gestation.

Animals↗
PubMed1988

Effects of perinatal exposure to a synthetic estrogen and progestin on mammary tumorigenesis in mice.

The effects of perinatal exposure to synthetic estrogens and progestins on mammary tumorigenesis were studied in female C3H/HeN/MTV + mice. Mice were treated neonatally with 0.001 microgram/day diethylstilbestrol (DES), with 15 micrograms/day 17 alpha-hydroxyprogesterone caproate (HPC), or with oil on days 1-5 of life (birth = day 1). As adults, neonatally hormone-treated mice received long-term treatment with a synthetic estrogen and progestin combination or vehicle. Animals were palpated weekly for mammary gland tumors. The effect of treatment on the probability of tumor development was examined. Neonatal treatment with a low dose of DES increased the probability of mammary-gland tumor formation, whereas neonatal treatment with HPC had a slightly protective effect on tumorigenesis. Subsequent treatment of adult mice with synthetic steroids did not affect mammary gland tumorigenesis in neonatally DES-treated or oil-treated animals. There was a significant interaction between the effect of neonatal HPC treatment and subsequent steroid treatment on mammary tumorigenesis but examination of the data indicated that this interaction was due to the protective effect of HPC in the absence of subsequent exposure to synthetic steroids and the probability of tumor appearance in mice treated with both HPC and synthetic steroids as adults did not differ from that of neonatally oil-treated controls.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed1988

Pituitary factors regulating mouse placental lactogen-II secretion during the last half of pregnancy in mice.

Hypophysectomy of mice during the last half of pregnancy results in an increase in the maternal serum mouse placental lactogen-II (mPL-II) concentration. The present study was undertaken to isolate and identify the pituitary factors that regulate mPL-II. Administration of pituitary extracts from virgin and day 12 pregnant mice (five pituitaries per mouse, every 8 h, sc) and bilateral pituitary implants under the kidney capsule significantly inhibited the increase in the mPL-II concentration that occurs within 24 h after hypophysectomy on day 12 of pregnancy, which indicated that the pituitary secretes factors that regulate mPL-II. To characterize these factors biochemically, pituitaries from virgin female mice were incubated for 14 days, and the culture medium was pooled, concentrated, and then fractionated by gel exclusion chromatography on Sephadex G-100, followed by ion exchange chromatography on DEAE. The fraction from DEAE chromatography that contained predominantly mouse (m) GH as well as a very small amount of a substance with an approximate mol wt of 23K suppressed the posthypophysectomy rise in serum mPL-II. To determine whether purified PRL, GH, and the unknown 23K substance present in the active fraction from the DEAE column could suppress the posthypophysectomy rise in serum mPL-II, repeated injections and constant infusion of these substances were carried out in hypophysectomized mice. Repeated injections of purified mPRL and bovine (b) PRL and constant infusion of mPRL were without effect. Repeated injection of mGH at doses of 1 and 10 micrograms/mouse or of bGH at doses of 50, 150, and 450 micrograms/mouse were also not effective, but bGH injections at a dose of 5 mg/mouse suppressed the posthypophysectomy rise in serum mPL-II. Subsequently, two pools of mGH were prepared by ion exchange HPLC; mGH-A contained predominantly mGH as well as a very small amount of an unidentified 23K mol wt substance, and mGH-B contained only mGH. When mGH-A and mGH-B were infused at a constant rate into hypophysectomized pregnant mice, both suppressed serum mPL-II concentrations; there was no difference in activity between mGH-A and mGH-B. These results indicate that mGH, but not mPRL, regulates the serum PL-II concentration in the mouse. mPL-II secretion is under the inhibitory control of mGH, the concentration of which increases rapidly at the beginning of the last half of pregnancy.

Animals↗
PubMed1988

Biological, immunological, and binding properties of recombinant mouse placental lactogen-I.

Mouse placental lactogen-I (mPL-I) cDNA was inserted into a eukaryotic expression vector and introduced into Chinese hamster ovary cells. Cell lines that secrete high concentrations of mPL-I were isolated, and this glycoprotein was purified from the cell culture-conditioned medium. Recombinant mPL-I (mPL-Ir) is very similar to placental mPL-I (mPL-Ip) in its recognition by polyclonal antisera raised against either mPL-Ip or mPL-Ir, in displacing [125I]iodo-mPL-II from binding sites on mouse liver microsomal membranes, and in stimulating the synthesis of alpha-lactalbumin in primary cultures of mouse mammary epithelial cells. Structural comparison of mPL-Ir and mPL-Ip by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that mPL-Ir comprises several proteins with mol wt ranging from 34.5-38K, while mPL-Ip consists of a similar set of proteins with mol wt ranging from 36.5-42K. Treatment of the two proteins with neuraminidase resulted in similar 2-4K decreases in mol wt. Treatment of mPL-Ip with peptide:N-glycosidase-F to remove asparagine-linked oligosaccharide chains resulted in the formation of 28K and 29K mol wt species, while treatment of mPL-Ir with the same enzyme yielded 28K and 28.5K mol wt products.

Animals↗
PubMed1987

Effects of fasting on serum lactogenic hormone concentrations during mid- and late pregnancy in mice.

Hormonal and metabolic responses to fasting were studied in pregnant Swiss Webster mice. Food was removed from pregnant mice 12, 24, 36, or 48 h before death on day 12 or 15 of pregnancy. Serum mouse placental lactogen-II (mPL-II), mouse growth hormone (mGH), mouse prolactin (mPRL), free fatty acids (FFA), and glucose concentrations were determined for each group. In comparing fasted animals with fed controls, there was a significant increase in the serum mPL-II concentration after 24 and 48 h of fasting on day 12 and after 12, 36, and 48 h of fasting on day 15. Fasting significantly decreased the glucose and increased the FFA concentration of the serum at all fasting periods. Fasting had no effect on serum mPRL or mGH concentrations. In the second part of this study, pregnant mice were fasted for 24 h and then refed for an additional 24 h before being killed on day 12 of pregnancy. The changes in serum mPL-II, glucose, and FFA concentrations that occurred after a 24-h fast on day 12 of pregnancy were completely reversed by refeeding the animals for 24 h. Results from both studies indicate the involvement of mPL-II in the maternal response to fasting in pregnant mice.

Animals↗
PubMed1987

Purification and partial characterization of two prolactin-like glycoprotein hormone complexes from the midpregnant mouse conceptus.

Two PRL-like glycoprotein hormone complexes were purified from the medium of cultured mouse conceptuses from day 10 of pregnancy: mouse placental lactogen-I (mPL-I) (29-32K), and mPL-I (36.5-42K). Sodium dodecyl sulfate-gel electrophoresis revealed that mPL-I (36.5-42K) is a complex of five proteins with mol wt of 36.5K, 37.5K, 39K, 40.5K, and 42K. Deglycosylation with peptide: N-glycosidase F or trifluoromethanesulfonic acid produced a single 29K protein. mPL-I (36.5-42K) was also sensitive to neuraminidase, but not to endo-beta-N-acetylglucosaminidase H or bacterial alkaline phosphatase. The production of intermediates from partial digestion of mPL-I (36.5-42K) with endo-beta-N-acetylglucosaminidase F indicated the presence of multiple glycosylation sites. mPL-I (29-32K) is a complex of three proteins with mol wt of 29K, 30.5K, and 32K. Treatment with peptide:N-glycosidase F or trifluoromethanesulfonic acid reduced the mol wt of the 30.5K and 32K bands to 28K. The 30.5K band was sensitive to endo-beta-N-acetylglucosaminidase H and endo-beta-N-acetylglucosaminidase F, but the 32K band was not. Neither band was sensitive to neuraminidase or bacterial alkaline phosphatase. The 29K band was resistant to all chemical and enzymatic treatments and is probably not glycosylated or phosphorylated. In the nonreduced state, neither form of mPL-I showed an increase in mobility over that of its reduced counterpart on sodium dodecyl sulfate-gel electrophoresis, indicating that neither form of mPL-I contains the large disulfide loop common to hormones of the PRL family. After iodination, all component proteins of both forms of mPL-I were found to bind to day 17 pregnant mouse liver membranes and were displaceable by excess mPL-II. In a radioreceptor assay, 125I-labeled mPL-I (36.5-42K) was displaced by mPRL or mPL-II, but not by mGH. An antiserum to both forms of mPL-I was generated, and a RIA employing mPL-I (36.5-42K) as the standard and radioligand was developed. Dilutions of day 10 pregnant maternal mouse serum and placental homogenate and a partially purified fraction of mPL-I (29-32K) produced displacement curves parallel to that of mPL-I (36.5-42K) standard curve. Five micrograms of mPRL, mPL-II, or mGH or 10 microliter day 17 pregnant or male mouse serum did not displace the radioligand from the antibody. mPL-I (36.5-42K) was lactogenic, but it did not possess LH-like bioactivity.

Animals↗
PubMed1986

Neonatal diethylstilbestrol treatment: response of prolactin to dopamine or estradiol in adult mice.

The effects of neonatal diethylstilbestrol (DES) treatment on pituitary PRL response to dopamine (DA) inhibition or estrogen stimulation were studied in C3H/MTV+ mice at 10 weeks, 5 months and 8 months of age using synthesis and release of [3H]PRL by the pituitary as endpoints. In the DA study, anterior pituitaries from ovariectomized or intact, neonatally hormone-treated mice were incubated for 6 h in the presence or absence of DA. In the estrogen study, serum and anterior pituitaries were obtained from ovariectomized neonatally hormone-treated mice injected with oil or 17 beta-estradiol for 7 days before death. Neonatal treatment of mice with 2.5 micrograms/day DES altered basal [3H]PRL synthesis and release as well as circulating PRL concentrations. The results of analysis of variance indicated a significant interaction between the effects of neonatal hormone treatment and DA treatment on [3H]PRL release. Neonatal DES treatment did not alter the response of pituitary PRL to estrogen treatment at the ages examined.

Animals↗
PubMed1986

The sensitivity of prolactin secretion to dopamine changes during pregnancy in mice.

Pituitary responsiveness to dopamine was investigated on several days of pregnancy in the mouse. Sera and anterior pituitary glands were obtained at 09.00 and 18.00 h on day 5 of pregnancy and at 09.00 h on days 12 and 18, and the pituitaries were incubated for 5 h in several concentrations of dopamine (0, 5 X 10(-10)--5 X 10(-7)M). Serum prolactin (Prl) concentration was the highest on day 5 (18.00 h sample), followed by day 18 (09.00 h), day 5 (09.00 h) and day 12 (09.00 h). Pituitary responsiveness to dopamine was assessed on each day of pregnancy by determining the slopes of dose-response curves in which the Prl concentration of the medium was plotted as a function of dopamine concentration. The slope of the dose-response curve for pituitaries from day 12 or pregnancy was significantly steeper than the slopes of the curves for pituitaries from days 5 and 18, which did not differ from each other. These data suggest that the Prl secretion mechanism is more sensitive to inhibition by dopamine on day 12 of pregnancy, when serum Prl concentration is very low, than on days 5 or 18, when serum Prl concentrations are higher. One of the mechanisms by which circulating Prl concentrations are reduced to very low levels during midpregnancy in the mouse may be increased pituitary sensitivity to dopamine.

Animals↗
PubMed1986

Lactogenic response of cultured mouse mammary epithelial cells to mouse placental lactogen.

The ability of mouse placental lactogen (mPL), mouse prolactin (mPRL), mouse GH (mGH) and ovine prolactin (oPRL) to stimulate synthesis of alpha-lactalbumin was tested in a primary culture of mouse mammary gland epithelial cells. Mammary tissue was obtained from 10-day pregnant Swiss Webster mice, enzymatically dissociated and the cells were cultured on floating collagen gels for 5 days. The basic culture medium consisted of Nutrient Mixture F12/Dulbecco's Modified Eagle's Medium (1:1, v/v), containing 10 mg insulin/1, 5 mg cortisol/l, 10 micrograms epidermal growth factor/l, 5 g bovine serum albumin/l and 50 mg gentamycin/l. Mouse PL, mPRL, mGH and oPRL were added to the basic medium in concentrations from 1 microgram/l to 1 mg/l. Accumulation of alpha-lactalbumin in the culture medium was measured. For that purpose, mouse alpha-lactalbumin was purified from mammary tissue obtained from lactating Swiss Webster mice and a radioimmunoassay was developed. Mouse PL, mPRL and oPRL stimulated a dose-dependent increase in alpha-lactalbumin secretion. Mouse GH also caused a significant, but dose-independent, increase in alpha-lactalbumin secretion. Mouse PL showed the greatest activity in stimulating alpha-lactalbumin secretion. It was concluded that mPL is an important lactogenic hormone in the latter half of pregnancy in the mouse, when circulating mPRL concentrations are low.

Animals↗
PubMed1985

Identification of proliferin mRNA and protein in mouse placenta.

Proliferin is a recently described, prolactin-related protein whose mRNA appears in several murine cell lines during active growth. We have surveyed a number of mouse organs or tissues for the presence of mRNAs that hybridize to cloned proliferin cDNA. Of the tissues tested, only the placenta yielded proliferin-related mRNA. This placental RNA is about 1 kilobase in length, increases sharply between days 8 and 10 of pregnancy, and then gradually declines through day 18. It is more abundant in RNA extracted from the fetal, compared to the maternal, part of the placenta. From a cDNA plasmid library prepared from poly(A)+ placental RNA, two types of proliferin-related clones were isolated, differing in intensity of hybridization to proliferin cDNA. By nucleotide sequence analysis, a strongly hybridizing clone was found to be nearly identical to the proliferin cDNA clone isolated from a library prepared from mRNA of a growing mouse fibroblastic cell line. Using an antiserum prepared against a synthetic proliferin fusion protein, we show that proliferin is secreted as a glycoprotein by minced placental tissue and that it differs from mouse placental lactogen. We conclude that proliferin is a placental hormone that is synthesized in certain mouse cell lines during active growth. Its function during pregnancy and during the growth of cultured cells is presently unknown.

Amino Acid Sequence↗
PubMed1984

Effects of neonatal treatment with diethylstilbestrol and 17 alpha-hydroxyprogesterone caproate on in vitro pituitary prolactin secretion.

The effects of neonatal hormone treatment with diethylstilbestrol (DES) and 17 alpha-hydroxyprogesterone caproate (HPC) on days 1-5 of life on serum prolactin (PRL) levels and 3H-PRL synthesis and release were studied in C3H/MTV+ mice at 2, 4, 6, 8 and 10 weeks of age. Neonatal treatment of mice with 2.5 micrograms/day DES was the only treatment that affected the developmental pattern of serum PRL levels. Serum PRL levels were significantly decreased at 6 wks of age with this dose of DES. Neonatal treatment with 2.5 micrograms/day DES and 150 micrograms/day HPC affected the developmental pattern of H-PRL synthesis by the pituitary. At 10 wks of age 3H-PRL synthesis was significantly decreased by these doses of DES and HPC. The percent of 3H-PRL released did not differ between neonatally hormone treated and control animals, suggesting that neonatal treatment affected mechanisms that regulate PRL synthesis but not those that regulate release.

17-alpha-Hydroxyprogesterone↗
PubMed1983

Identification and partial characterization of a lactogen from the midpregnant mouse conceptus.

Previously, we demonstrated that measurement of serum lactogenic hormones during pregnancy in the mouse by the rabbit mammary gland radioreceptor assay (RRA) and specific RIAs for mouse PRL (mPRL) and mouse placental lactogen (mPL) showed a large RRA to RIA activity ratio during midpregnancy. The purpose of this study was to begin to characterize this discrepancy in midpregnancy PRL-like activity. The elution profile of serum from midpregnant mice on Sephadex G-100 showed a characteristic peak in RRA activity (elution volume/void volume = 1.5), distinct from either mPRL or mPL (both approximately elution volume/void volume = 2.0). This PRL-like activity was not recognized by antisera to either mPRL or mPL. The source of the midpregnancy lactogen was localized to the conceptus. The hormone was found to have an apparent molecular weight of 50,000 (based on Sephadex G-100 chromatography) and an electrophoretic mobility similar to mPRL (Rf = 0.5-0.6) and to be lactogenic in the in vitro mouse mammary gland explant bioassay. We have demonstrated the existence of a midpregnancy lactogen that is different from mPL and mPRL and is of conceptus origin.

Animals↗
PubMed1982

Isolation, purification, and characterization of mouse placental lactogen.

Mouse placental lactogen was purified 1840-fold from BALB/c placentae from days 14-18 of gestation with an overall yield of 29%. The purification procedure included alkaline homogenization and extraction, ammonium sulfate precipitation, hydrophobic interaction chromatography on Phenyl-Sepharose, ion-exchange chromatography on CM- and DEAE-cellulose, and gel exclusion chromatography on Sephadex G-100. On 10% alkaline polyacrylamide gels, mouse placental lactogen had an Rf of 0.19. Electrophoresis in gels containing NaDodSO4 showed a single band with a mobility corresponding to a Mr of 23,000 +/- 1000. The isoelectric point, determined by isoelectric focusing in 8 M urea/5% 2-mercaptoethanol, was 7.1. When tested in the pigeon crop sac assay, 10 micrograms of mouse placental lactogen produced stimulation comparable with that evoked by 10 micrograms of ovine prolactin. In the rabbit mammary gland radioreceptor assay, mouse placental lactogen was 150% more potent than ovine prolactin in displacing 125I-labeled ovine prolactin from rabbit mammary gland membranes. Iodinated purified mouse placental lactogen could be displaced from rabbit mammary gland membranes by mouse placental lactogen, mouse prolactin, and ovine prolactin. Ovine prolactin was 45% as avid as mouse placental lactogen is displacing 125I-labeled mouse placental lactogen from rabbit mammary gland membranes. Mouse placental lactogen did not crossreact with antisera to mouse prolactin or mouse growth hormone in a radioimmunoassay.

Animals↗
PubMed1981

Isolation and partial characterization of secreted hamster pituitary prolactin.

PRL secreted by hamster anterior pituitaries was purified by gel filtration on Sephadex G-100 and ion exchange chromatography on DEAE-cellulose. Hamster PRL eluted from Sephadex G-100 with an elution volume to void volume ratio of 1.85 and at a salt concentration of 0.13 M NaCl on DEAE-cellulose. Electrophoretic homogeneity of the hormone was demonstrated in several gel systems, and electrophoresis in the presence of sodium dodecyl sulfate indicated a molecular weight of 22,000 +/- 2,000. Hamster PRL did not cross-react with antiserum to mouse PRL. Hamster PRL displayed lactogenic activity in an in vitro mouse mammary gland assay. Hamster PRL displaced [125I]iodo-PRL from lactating rabbit mammary gland receptors. Thus, with respect to its exclusion properties on SEphadex G-100, its molecular weight, and its biological activity, hamster PRL closely resembles other mammalian PRLs.

Animals↗
PubMed1980

Phylogenetic distribution, regulation of secretion, and prolactin-like effects of placental lactogens.

The occurrence of placental lactogens has been reported for members of 4 orders, 7 families, and 15 genera, while its absence has been documented in representatives from 4 orders, 5 families, and 5 genera. Placental lactogens from several genera have been isolated, purified, and characterized biochemically. The cellular sites of production and patterns of secretion of placental lactogens have been described. The regulation of placental lactogen secretion is not understood, although its synthesis and release can be modified experimentally by altering metabolic, ionic, and hormonal factors in the placental environment. Placental lactogens stimulate lactogenesis and steroidogenesis. The mechanism underlying placental lactogen's role in these processes has not been clarified.

Animals↗
PubMed1979

Lactogenic response of mouse mammary explants from different days of pregnancy to placental lactogen and pituitary prolactin.

The lactogenic response of mouse mammary gland explants to human placental lactogen (hPL) and ovine pituitary prolactin (oPRL) was examined on days 10 to 18 of pregnancy by measuring 3H-amino acid incorporation into calcium-rennin precipitable casein. To determine the lactogenic response of the explants, the mean slopes of dose-response curves were calculated for each hormone treatment. Slope means of dose-response curves for oPRL and hPL did not differ from each other on any day of pregnancy examined. A triphasic pattern of response was suggested when slope means of dose-response curves for both hormones were plotted as a function of day of gestation. Peak responses were observed on days 10, 13 and 17-18. Combinations of oPRL and hPL, in ratios of oPRL:hPL = 2:1 and oPRL:hPL = 1:2, also produced a triphasic pattern of sensitivity very similar to that produced by either hormone alone. These results suggest that mouse mammary explants may be more sensitive to oPRL and hPL on days 10, 13 and 17-18 of pregnancy.

Animals↗