Investigations on hormonal changes around parturition in the dog and the occurrence of pregnancy-specific non conjugated oestrogens

Hoffmann, Bernd; Höveler, R.; Nøhr, Bugge; Hasan, S. H.

doi:10.1055/s-0029-1211280

Cited by 93 publications

(96 citation statements)

References 8 publications

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“…This hormone profile precludes progesterone as a usable marker for detection of pregnancy in the bitch. Moreover, no pregnancyassociated increase in estrogens is observed in the dog (Hoffmann et al 1994).…”

Section: Introductionmentioning

confidence: 86%

Expression of genes involved in the embryo–maternal interaction in the early-pregnant canine uterus

et al. 2014

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Although there is no acute luteolytic mechanism in the absence of pregnancy in the bitch, a precise and well-timed embryo-maternal interaction seems to be required for the initiation and maintenance of gestation. As only limited information is available about these processes in dogs, in this study, the uterine expression of possible decidualization markers was investigated during the pre-implantation stage (days 10-12) of pregnancy and in the corresponding nonpregnant controls. In addition, the expression of selected genes associated with blastocyst development and/or implantation was investigated in embryos flushed from the uteri of bitches used for this study (unhatched and hatched blastocysts). There was an upregulated expression of prolactin receptor (PRLR) and IGF2 observed pre-implantation. The expression of PRL and of IGF1 was unaffected, and neither was the expression of progesterone-or estrogen receptor b (ESR2). In contrast, (ESR1) levels were elevated during early pregnancy. Prostaglandin (PG)-system revealed upregulated expression of PGE2-synthase and its receptors, PTGER2 and PTGER4, and of the PG-transporter. Elevated levels of AKR1C3 mRNA, but not the protein itself, were noted. Expression of prostaglandin-endoperoxide synthase 2 (PTGS2) remained unaffected. Most of the transcripts were predominantly localized to the uterine epithelial cells, myometrium and, to a lesser extent, to the uterine stroma. PGES (PTGES) mRNA was abundantly expressed in both groups of embryos and appeared higher in the hatched ones. The expression level of IGF2 mRNA appeared higher than that of IGF1 mRNA in hatched embryos. In unhatched embryos IGF1, IGF2, and PTGS2 mRNA levels were below the detection limit.

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Section: Introductionmentioning

confidence: 86%

Expression of genes involved in the embryo–maternal interaction in the early-pregnant canine uterus

et al. 2014

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“…To monitor adrenal activity during the periods of frequent blood sampling, cortisol concentrations were determined using an inhouse radioimmunological method as previously described (Hoffmann et al 1994) after extraction of the samples with ethyl acetate. The antiserum was directed against 4-pregnene-11b,17a,21-triol-3,20-dione-3-(O-carboxymethyl) oxime-BSA.…”

Section: Sample Collection From Hcg-stimulated Boarsmentioning

confidence: 99%

Free and sulfated steroids secretion in postpubertal boars (Sus scrofa domestica)

et al. 2014

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Sulfated steroids have been traditionally regarded as inactive metabolites. However, they may also serve as precursors for the production of active free steroids in target cells. In this study, we used the boar as a model to study the metabolism, transport, and function of steroid sulfates due to their high production in the porcine testicular-epididymal compartment, of which the role is unknown. To characterize the secretion of free and sulfated steroids, plasma samples were collected from six postpubertal boars over 6 h every 20 min from the jugular vein. Long-term secretion profiles were also established in seven boars stimulated with human chorionic gonadotropin. To directly characterize the testicular output, samples were collected from superficial testicular arterial and venous blood vessels. Testosterone, androstenedione and sulfated pregnenolone, DHEA, estrone (E 1 ), and estradiol-17b (E 2 ) were determined by liquid chromatography-tandem mass spectrometry. Free E 1 and E 2 were measured by RIA. Irrespective of a high variability between individuals, the results suggest that i) all steroids assessed are primarily produced in the testis, ii) they exhibit similar profiles pointing to a pulsatile secretion with low frequency (three to five pulses per day), and iii) after synthesis at least a major proportion is immediately released into peripheral circulation. The fact that all steroid sulfates assessed are original testicular products and their high correlations with one another suggest their role as being intermediates of testicular steroidogenesis rather than as being inactivated end products. Moreover, a substantial use of sulfated steroids in porcine testicular steroidogenesis would assign a crucial regulatory role to steroid sulfatase, which is highly expressed in Leydig cells.

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“…The resulting course of progesterone (P 4 ) concentrations in peripheral plasma is almost identical in pregnant and nonpregnant dogs until about day 60 of luteal lifespan when the more gradual decline observed so far turns into a steep one as a precondition for parturition, which generally occurs 63 days after mating. In the nonpregnant dog, however, the gradual decline continues to levels !1 ng/ml about 10-20 days later (Concannon et al 1989, Hoffmann et al 1994. These deviating patterns in P 4 secretion may be seen as an indication for different mechanisms regulating a) gradual luteal regression in nonpregnant dogs and b) prepartal luteolysis.…”

Section: Introductionmentioning

confidence: 99%

Canine placenta: a source of prepartal prostaglandins during normal and antiprogestin-induced parturition

et al. 2010

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Expression of cyclooxygenase 2 (COX2, now known as PTGS2), prostaglandin E2 synthase (PTGES, PGES), and prostaglandin F2a synthase (PGFS), of the respective receptors PTGFR (FP), PTGER2 (EP2), and PTGER4 (EP4) and of the progesterone receptor (PGR, PR) was assessed by real-time PCR, immunohistochemistry (IHC), or in situ hybridization (ISH) in utero/placental tissue samples collected from three to five bitches on days 8-12 (pre-implantation), 18-25 (post-implantation), and 35-40 (mid-gestation) of pregnancy and during the prepartal luteolysis. Additionally, ten mid-pregnant bitches were treated with the antiprogestin aglepristone (10 mg/kg bw (2!/24 h)); ovariohysterectomy was 24 and 72 h after the second treatment. Plasma progesterone and 15-ketodihydro-PGF2a (PGFM) concentrations were determined by RIA. Expression of the PGR was highest before implantation and primarily located to the endometrium; expression in the placenta was restricted to the decidual cells. PTGS2 was constantly low expressed until mid-gestation; a strong upregulation occurred at prepartal luteolysis concomitant with an increase in PGFM. PGFS was upregulated after implantation and significantly elevated through early and mid-gestation. PTGES showed a gradual increase and a strong prepartal upregulation. PTGFR, PTGER2, and PTGER4 were downregulated after implantation; a gradual upregulation of PTGFR and PTGER2 occurred towards parturition. ISH and IHC co-localized PGFS, PTGFR, PTGES, and PTGS2 in the trophoblast and endometrium. The changes following application of aglepristone were in the same direction as those observed from mid-gestation to prepartal luteolysis. These data suggest that the prepartal increase of PGF2a results from a strong upregulation of PTGS2 in the fetal trophoblast with the withdrawal of progesterone having a signalling function and the decidual cells playing a key role in the underlying cell-to-cell crosstalk.

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Investigations on hormonal changes around parturition in the dog and the occurrence of pregnancy-specific non conjugated oestrogens

Cited by 93 publications

References 8 publications

Expression of genes involved in the embryo–maternal interaction in the early-pregnant canine uterus

Expression of genes involved in the embryo–maternal interaction in the early-pregnant canine uterus

Free and sulfated steroids secretion in postpubertal boars (Sus scrofa domestica)

Canine placenta: a source of prepartal prostaglandins during normal and antiprogestin-induced parturition

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