Effects of beta 2-adrenergic stimulants on the progesterone and oestradiol-17 beta serum levels in pseudopregnant rats.

In CFY rats pseudopregnancy (PSP) was induced by mechanical stimulation of cervix uteri. On the days 1 or 7 of PSP indvelling catheter was built in one of the jugular veins and blood was collected daily until 7th or 14th days of PSP respectively, meanwhile the animals were daily injected with clenbuterol (0.1 mg/kg bw), fenoterol (0.5 mg/kg bw), ritodrin (1.0 mg/kg bw), propranolol (2.0 mg/kg bw) or 1.0 ml/kg bw 0.9% NaCl subcutaneously. From the blood samples progesterone (P) and oestradiol-17 beta (E2) were determined by RIA. beta 2-adrenergic agonists did not influence the serum levels of P either in the first or in the second half of PSP and the propranolol failed to alter also the serum levels of P during the PSP. Clenbuterol and ritodrin, however, decreased the serum levels of E2 in the first half of PSP, while in the second half of PSP fenoterol and ritodrin elevated, the propranolol diminished it. It was supposed that in PSP rats beta 2-adrenergic mechanism has a more pronounced effects on the theca-interstitial cells than that of the luteal cells.     

Circulating progesterone and oestradiol-17 beta concentrations in cyclic Cape porcupines, Hystrix africaeaustralis

The general pattern of steroid secretion during the 30-day oestrous cycle of the Cape porcupine is that of a surge (25-176 pg/ml) in oestradiol-17 beta secretion at the time of perforation of the vaginal closure membrane, followed by an increase in progesterone concentrations, the latter attaining peak values (mean 5.9 +/- 2.1 ng/ml) 8-19 days (13.8 +/- 2.8 days) after vaginal opening. Copulation occurred after the oestradiol-17 beta surge and the length of the luteal phase of the cycle varied from 21 to 35 days (29.3 +/- 4.7 days), this representing 93% of the length of the cycle. Perforation of the vaginal closure membrane was not always accompanied by an increase in oestradiol-17 beta levels and some instances (19%) of vaginal opening were not followed by an increase in progesterone secretion. The hormonal characteristics of the oestrous cycle of females housed with vasectomized males were similar to those of females housed with intact males.     

Metabolism of oestradiol-17 beta and progesterone in the white rhinoceros (Ceratotherium simum simum)

14C-Labelled oestradiol-17 beta and progesterone (50 mu Ci each) were injected i.v. into an adult female white rhinoceros and all urine and faeces collected separately over the next 4 days. The total recovery of injected label was 61%, 25% being present in the urine and 36% in the faeces. Of the radioactivity recovered, 69% was excreted on Day 2 of the collection period. Repeated extraction of samples obtained on Day 2 showed that, of the radioactivity in faeces, 92.4% was associated with unconjugated steroids whereas in the urine the proportion of conjugated and unconjugated steroids were similar (41.2% and 51.4% respectively). After phenolic separation of urinary steroids, HPLC followed by derivatization and recrystallization techniques identified progesterone as the major component of the unconjugated portion with 4-pregnen-20 alpha-ol-3-one as the principal metabolite in the conjugated fraction. Pregnanediol was not present. Oestrone appeared to be the most abundant oestrogen metabolite with smaller but significant amounts of oestradiol-17 beta and oestradiol-17 alpha in the unconjugated and conjugated fractions respectively. Small amounts of progesterone were found in the faecal extract in which the radioactivity consisted mainly of oestradiol-17 alpha and oestradiol-17 beta. The results have established the major excreted metabolites of oestradiol-17 beta and progesterone in the white rhinoceros and the development of more appropriate assay methods for monitoring ovarian function in African rhinoceroses should now be possible.     

Effect of oestradiol-17 beta and progesterone on oviductal transport and early development of mouse embryos

Transport of embryos through the oviduct, cleavage rate and transformation of morulae to blastocysts, were delayed in females ovariectomized on Day 2 of pregnancy. Oestradiol-17 beta in doses of 60 to 6000 pg/day for 3 days did not normalize the transport of embryos, but the transformation of morulae to blastocysts reached values near or equal to those of the controls, in spite of a lowered rate of cleavage. Progesterone at a dose of 100 micrograms/day, resulted in normal transport, rate of cleavage and rate of differentiation. Treatment with both hormones had synergistic effects on transport and the rate of cleavage and differentiation. These results give further support to the concept that ovarian hormones are the controlling factors for these processes in early pregnancy.     

In-vitro zona-lytic activity in uterine fluid from ovariectomized mice treated with oestradiol-17 beta and progesterone

Mouse embryos collected before implantation were incubated in vitro for 24 h with fluid rinsed from the uteri of ovariectomized female mice injected with progesterone, oestradiol-17 beta + progesterone, oestradiol-17 beta + progesterone, or oestradiol-17 beta alone. Although none of the zonae was completely dissolved, those incubated in fluid from animals treated with oestradiol + progesterone were subsequently more soluble in sodium thiocyanate (NaSCN) than those incubated similarly in control buffer, indicating a sublytic change during the incubation with uterine washings. Zonae incubated in fluid from animals injected with either hormone alone did not undergo such a change.     

Effects of progesterone and oestradiol-17 beta on oxytocin-induced release of prostaglandin F-2 alpha in heifers

Seven bilaterally ovariectomized heifers were used in 4 experiments and received: (1) saline injections, as control; (2) one injection of oestradiol (3 mg; i.v.); (3) two i.v. injections of oxytocin (100 i.u.) 6 h apart; or (4) one oestradiol injection 30 min after the first oxytocin injection and a second oxytocin injection 6 h later. All experiments were performed without progesterone and then after 7, 14 and 21 days of progesterone treatment. Frequent blood samples were taken for 1 h before and 7 h after the first injection of oxytocin or oestradiol for the measurement of 13,14-dihydro-15-keto-PGF-2 alpha (PGFM) by radioimmunoassay. After 7, 14 and 21 days of progesterone priming, oestradiol caused a significant increase (P less than 0.001) in plasma PGFM after 6 h but not before. After 7, 14 and 21 days of progesterone, there was a significant increase (P less than 0.005) in PGFM after the first oxytocin injection and a similar increase following the second. The oxytocin-induced increase in PGFM after 14 and 21 days of progesterone was significantly higher (P less than 0.001) 6 h after oestradiol injection than before the oestradiol injection. There was no significant effect of oestradiol on the response to oxytocin in animals that received no progesterone or in those animals that received progesterone for only 7 days. These results show that, under the influence of progesterone, oestradiol enhances the oxytocin-induced release of PGF-2 alpha, and suggest a possible synergistic action of these hormones for the induction of luteolysis in heifers.     

Phosphorylation on tyrosine of oestradiol-17 beta receptor in uterus and interaction of oestradiol-17 beta and glucocorticoid receptors with antiphosphotyrosine antibodies

In whole rat uterus incubated in the presence of [32P]orthophosphate the oestradiol receptor is [32P]phosphorylated on tyrosine. This finding follows our previous observation that in vitro this receptor can be phosphorylated on tyrosine by a uterus kinase that endows the receptor with oestradiol-binding activity. The calf uterus oestradiol receptor interacts with high affinity with 2G8 and 1G2 antiphosphotyrosine antibodies coupled to Sepharose (Kd values of 0.28 and 1.1 nM, respectively). The interaction with 2G8 antibody has been exploited to purify the oestradiol receptor. This interaction disappears after inactivation of the oestradiol receptor by the nuclear phosphatase that hydrolyses phosphotyrosine of the receptor. This fact substantiates the evidence that the oestradiol receptor in uterus is phosphorylated on tyrosine and that this phosphorylation is required for hormone binding to the receptor. The rat liver glucocorticoid receptor also interacts with high affinity with 2G8 antiphosphotyrosine antibody coupled to Sepharose (Kd value of 0.21 nM). This receptor has been purified by using in sequence heparin-Sepharose and antiphosphotyrosine antibody-Sepharose.     

Metabolism of oestradiol-17beta by intestinal bacteria in rats.

In vitro experiments were carried out in which [4-14C]oestradiol-17beta was incubated with a culture from caecal content from adult male rats at 37 degrees C in an atmosphere of nitrogen. Oestrone was identified as the only certain metabolite. Other metabolites, if present, were quantitatively unimportant. The conversion of oestradiol-17beta to oestrone was estimated to be 22-42%.     

Pituitary response of prepuberal lambs to oestradiol-17 beta.

In two experiments 48 prepuberal Merino ewe lambs were injected with oestradiol-17 beta (E2) or saline to study the effect of E2 on their plasma LH levels and on oestrus and ovulation. In the three groups which received 30 (experiment I), 50 and 30 (experiment II) microgram E2 respectively, 27 out of 28 lambs showed an LH response, the corresponding mean LH peaks being 64.3 +/0 22.5, 153.6 +/-33.4 and 91.7 +/- 16.9 ng/ml at mean intervals of 11.1, 11.2 and 10.5 h, respectively, after injection. None of the 20 lambs in the control groups had an LH level higher than 18 ng/ml 12 h after injection. In the three E2 groups, 41.7, 62.5 and 37.5% of animals showed oestrus within 26 h of injection while in the control groups only one animal showed oestrus. Of 13 animals showing oestrus in the E2 groups, 11 failed to ovulate. The mean pre-injection plasma FSH level in experiment I was 102.7 ng/ml, and in four 5--7-month-old lambs over several weeks uas 155.3 ng/ml. Despite these high pre-injection levels of FSH, it appears that the follicles were unable to respond to the LH peak which followed the E2 injection.     

Effects of oestradiol-17 beta and progesterone on the number of plasma cells in uteri of ovariectomized mice

Immunoglobulins A and G were localized by immunoperoxidase labelling in uteri of ovariectomized mice treated with oestradiol-17 beta and progesterone. The administration of oestradiol or progesterone alone to ovariectomized mice for 3 days increased the number of IgA plasma cells from about 1 to 14 per histological section. When the two hormones were administered simultaneously for 3 days the number of plasma cells per section was equal to or greater than with either hormone alone. Treatment with oestradiol followed by progesterone in a sequence that prepares the uterus for implantation resulted in about 31 IgA plasma cells per section. Counts of IgG plasma cells showed similar trends but the numbers were smaller. The results indicate that progesterone increases rather than decreases the number of plasma cells in the mouse uterus. This is consistent with observations on intact mice during oestrus and pregnancy and suggests that the marked increase in endometrial plasma cells at the time of implantation in mice is a response to progesterone acting on an oestrogen-primed uterus.     

Circulating progesterone, progesterone-binding proteins and oestradiol-17 beta concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis

Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17 beta in pregnant porcupines remained relatively low until Days 25-30 post coitum. Progesterone values peaked (102-180 ng/ml; N = 3) 42-60 days post coitum and the rapid increase in oestradiol-17 beta concentrations approximated that of progesterone with peak values (170-210 pg/ml) being attained 60-85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (less than 20 pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50-56 and Days 73-77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.