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A Ziecik

Publications and source records attributed to A Ziecik.

12 recordsLinked to original sources
PubMed1989

Active and passive immunization against luteinizing hormone in pigs.

Active immunization of four adult pigs with highly purified porcine luteinizing hormone (pLH)--using method of multiside intradermal injections--has been performed and resulted in the production of specific antibodies. Immunization caused prolongation of estrous cycle to 47-49 days in two gilts and to 26 days in the other ones. Obtained anti-pLH pig serum was administered intravenously to 40 day pregnant gilt during 5 days (10 ml of serum, twice daily). Blood plasma progesterone (P4) concentrations decreased significantly from 8-13 to 2-4 ng/ml after two days of infusion and remained at this level for the next 5 days. Administration of this anti-pLH pig serum to gilt in the luteal phase of the estrous cycle caused the inhibition P4 to undetectable amounts. The different results were found after the passive immunization of 40 day pregnant gilt with rabbit anti-pLH globulin preparation (5 days, equivalent to 3 ml of original undiluted serum, twice daily). Although after two days of infusion P4 concentration decreased, in the next days P4 level slowly increased to pretreatment concentrations. The data suggest the possibility of specific anti-pLH antibody production in pigs by using active immunization, and the repeated utilization of such obtained antiserum in the same species for the inhibition of corpus luteum (CL) function.

Animals↗
PubMed1987

Effect of human chorionic gonadotropin on preovulatory luteinizing hormone surge and ovarian hormone secretion in gilts.

The influence of varying doses of human chorionic gonadotropin (hCG) on the preovulatory luteinizing hormone (LH) surge, estradiol-17 beta (E2) and progesterone (P4) was studied in synchronized gilts. Altrenogest (AT) was fed (15 mg X head-1 X d-1) to 24 cyclic gilts for 14 d. Pregnant mares serum gonadotropin (PMSG; 750 IU) was given im on the last day of AT feeding. The gilts were then assigned to one of four groups (n = 6): saline (I), 500 IU hCG (II), 1,000 IU hCG (III) and 1,500 IU hCG (IV). Human chorionic gonadotropin or saline was injected im 72 h after PMSG. No differences in ovulation rate or time from last feeding of AT to occurrence of estrus were observed. All gilts in Groups I and II expressed a preovulatory LH surge compared with only four of six and three of six in Groups III and IV, respectively. All groups treated with hCG showed a rapid drop (P less than .01) in plasma levels of E2 11, 17, 23 h after hCG injection when compared with the control group (35 h). The hCG-treated gilts exhibited elevated P4 concentrations 12 h earlier than the control group (3.1 +/- .5, 3.4 +/- .72, 3.1 +/- .10 ng/ml in groups II, III and IV at 60 h post-hCG vs .9 +/- .08 ng/ml in group I; P less than .05). These studies demonstrate that injections of ovulatory doses of hCG (500 to 1,500 IU) had three distinct effects on events concomitant with occurrence of estrus in gilts: decreased secretion of E2 immediately after hCG administration, failure to observe a preovulatory LH surge in some treated animals and earlier production of P4 by newly developed corpora lutea.

Animals↗
PubMed1987

Action of GnRH on steroid secretion by luteal cells of cyclic and early pregnant sows in vitro.

The effect of GnRH was studied on progesterone (P4), oestradiol-17 beta (E2) and testosterone (T) secretion by porcine luteal cells from the 13th day of the oestrous cycle and the 18th day of pregnancy. Trypsin-dispersed luteal cells (5 X 10(4) cells/ml) were incubated in medium 199 with 10% calf serum with or without GnRH in doses of 0.1, 1, 10 and 100 mg/ml and with 1 microgram LH and 50 U/ml hCG. The concentration of P4, E2 and T in the medium was estimated by radioimmunological method after 6 hours of incubation. The results showed that GnRH had no effect on the secretion of the investigated steroid hormones by luteal cells from cyclic sows. GnRH at a dose of 10 g inhibited E2 secretion and at a dose of 1 ng T secretion by cells from pregnant sows. LH and hCG stimulated release of P4 by luteal cells in both physiological stages. The conclusion drawn was that GnRH does not act directly on luteal cells of cyclic sows but may inhibit E2 and T secretion by cells of pregnant sows.

Animals↗
PubMed1982

Porcine LH levels during the estrous cycle, gestation, parturition and early lactation.

Thirty-five sows were used in a study of plasma luteinizing hormone (LH) concentrations during the estrous cycle, including first and second estrus postweaning, during gestation, at parturition and during the first 5 d of lactation. After cannulation of the anterior vena cava via the cephalic vein, blood samples were collected four times daily for 2 d before estrus, during estrus and for 3 d after estrus and once daily at 1100 h throughout the rest of the estrous cycle. One sample was collected from each sow on alternate days (1100 h) during the gestation period. Four daily samples were obtained on d 60 through 68 of gestation and for 5 d after parturition. Preovulatory surges of LH occurred 8 to 32 h before standing estrus in four of seven sows during first estrus and in three of seven sows during second estrus. The mean preovulatory LH surge during the first estrus postweaning (3.00 +/- .46 ng/ml) was lower than that during second estrus (4.24 +/- .60 ng/ml). Throughout the first 12 d of gestation, LH concentrations were relatively high and variable, ranging from 1.2 to 2 ng/ml. They then decreased to a range of .42 to .62 ng/ml after d 24. Similar LH concentrations were noted throughout the remainder of gestation except for some slight fluctuations. Higher concentrations (P less than .05) were noted with evening collections (1900 h, 1:17 +/- .09 ng/ml) than in daytime collections (0700 h, .64 +/- .08: 1100 h, .61 +/- .06; 1500 h, .72 +/- .06 ng/ml) during d 60 to 68 of gestation. Low plasma concentrations of LH (.3 to .5 ng/ml) were observed for the 5 d before and during parturition. After parturition, considerable variation of LH occurred, with rising concentrations observed on d 5 postpartum. Results of this study illustrate the occurrence of LH surges before behavioral estrus with increased plasma LH during implantation.

Animals↗
PubMed1981

Effect of mating on the luteinizing hormone surge in the pig.

Twenty-eight cannulated crossbred gilts were assigned to one of four treatments: natural mating, artificial insemination (AI, whole semen), AI (seminal plasma) or control (nonmated). Blood samples were collected four times daily (0800, 1200, 1600 and 2000 hr) on the day before standing estrus, the day of the onset of standing estrus and the first day after the onset of standing estrus. Thereafter, blood samples were collected once daily (1200 hr) until 15 days postestrus. Analysis of luteinizing hormone (LH) in the plasma revealed similar concentrations for all groups on the day of estrus, but higher (P less than .05) values for naturally mated gilts the following morning. Mean concentrations of LH on the first day after the onset of standing estrus were higher (P less than .01) for the mated gilts (2.75 +/- .54 ng/ml) than for gilts in the AI whole semen (.89 +/- .10 ng/ml), AI seminal plasma (1.02 +/- .13 ng/ml) and control groups (.92 +/- .11 ng/ml). Concentration of LH in the plasma of pregnant gilts tended to be higher after day 9. These results suggest that coitus may prolong the LH surge.

Animals↗
PubMed1980

Luteal LH receptors during the oestrous cycle and early pregnancy in the pig.

The concentration, affinity constant and occupancy of the LH receptor have been measured in corpora lutea, from 29 pigs at Days 6--16 of the oestrous cycle, and from 25 pigs at Days 12--30 of pregnancy, by using 125I-labelled porcine LH tracer. Investigation of the specificity of the receptor showed that cross-reactions of other pituitary hormones were accounted for by their contamination with LH. Luteal concentration of unoccupied receptors doubled between Days 6 and 10 of the cycle, and decreased between Days 12 and 14; it increased 3-fold between Days 20 and 30 pregnancy, but was lower on Day 12 of pregnancy than at a comparable stage of the cycle. Concentrations of receptors occupied by LH increased early in the oestrous cycle, in parallel with the total receptor concentration; in pregnancy the percentage occupancy dropped dramatically as total receptor concentration increased between Days 20 and 30. Receptor affinity constants increased towards the end of the cycle and decreased between Days 20 and 30 of pregnancy. It is suggested that (1) the lower concentration of receptors in early pregnancy may reflect down regulation by circulating LH, concentrations of which are higher in early pregnancy than during the cycle; (2) the increase in receptor concentration between Days 20 and 30 or pregnancy may be due to a rise in circulating oestrogen levels; and (3) the decrease in occupancy at this time may be caused either by a decrease in affinity constant or by placental production of a chorionic gonadogrophin-like compound.

Animals↗
PubMed1979

Production of antibodies against the porcine luteinizing hormone by two immunization methods.

Two methods of rabbit immunization were applied: multisite intradermal injections of small doses and intramuscular injections of large hormone doses for obtaining antibodies against the porcine luteinizing hormone (LH). A high titre, specificity towards LH and affinity were obtained in rabbits immunized by both methods. In most animals the highest titre was noted 10 weeks after the first immunization.

Animals↗
PubMedDate not supplied

[Effect of large doses of manganese on erythropoietic activity].

The effect of intraperitoneal administration of 3 different doses of MnCl2 on erythro-poiesis was investigated in rats. Significant changes in 59Fe uptake by erythrocytes, bone marrow and spleen were observed in rats given the highest dose of 1 mg Mn/100 g of body weight. Six injections were necessary to produce a rise in the basic haematological indices, with the exception of reticulocytes whose number changed considerably during the period of investigations. The results of rat plasma filtrate administration to mice and total circulating blood volume determination which was unchanged after administration of MnCl2 suggested that the observed effects were produced by manganese. Histological examination of the liver, spleen and kidneys showed congestion and stasis of blood in them, especially in glomerular vessels.

Animals↗
PubMedDate not supplied

Influence of erythropoiesis stimulation on 54Mn distribution in rats.

The experiments were carried out on animals in which erythropoiesis was stimulated. The rats were anaemized by blood letting or they received subcutaneous injections of erythropoietic filtrate of anaemized sheep plasma. The investigations demonstrated that enhanced 54Mn incorporation into the erytrocytes and bone marrow is induced by stimulation of the erythropoiesis process, whereas the raised 54Mn level in the plasma of anaemized rats is associated with blood loss and not with erythropoiesis.

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