Untersuchen zur Regulation der uterinen und ovariellen Durchblutung sowie der Expression von Stickstoffmonoxidsynthasen und Östrogenrezeptoren im Verlauf des Zyklus und der Frühgravidität bei der Stute
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vor 22 Jahren
The aim of the present study was to estimate the influence of
uterine NOS-system and the sexual steroids estrogen and
progesterone on the blood supply of the uterus and the ovaries.
Five trotter mares were examined in total during four estrous
cycles and one early pregnancy. The investigations contained color
Doppler- and ultrasound recordings as soon as the extraction of
blood samples and endometrial biopsies. The first cycle was
medically uninfluenced and investigations were carried out on Days
0 (= ovulation), 1, 5, 11, 15 and daily during estrous, whereas in
estrous only one endometrial biopsy was taken. In the second cycle
luteal regression was induced on Day 5 of diestrous with the
PGF2α-analogon Tiaprost (Ilirenâ, 450 mg i.m.) and in estrous
ovulation was induced with hCG (Choriolutinâ, 2500 IE i.v.), when
the size of one follicle reached 35 mm. Investigations were carried
out in this cycle immediately before giving PGF2α and 0.5, 1, 3, 6,
12, 24, 36, 48 hours after that and then once a day up to
ovulation. Endometrial biopsies were taken in each case before
induction of luteolysis, 12 and 36 hours after that, before
injection of hCG and immediately after ovulation. During the
further two cycles the mares were treated orally with the NO donor
ISDN (ISDN 40â, 30 mg, twice a day). Investigations were carried
out on Days 0, 1 and 5 of the first cycle (ISDN I), as well as on
Days 11, 15 and during estrous of the second cycle (ISDN II).
During early pregnancy color Doppler recordings and blood samples
were taken on Days 0, 1, 5, 11 and 15 of pregnancy, while
endometrial biopsies were only gained on day 15. The analysis of
uterine blood flow was based on the time-averaged maximum velocity
(TAMV). Estrogens and progesterone were measured by an enzyme
immunoassay. Nitrate concentrations were evaluated using Griess
reacting. Total RNA was isolated from endo-metrial biopsies.
Transcriptes encoding the estrogen receptors a and b and the
endothelial as well as the inducible nitric oxide-synthase (eNOS
and iNOS) were quantified by RT-PCR-analysis. The expression of
eNOS-mRNA in control, as well as in the PGF2a-induced cycle,
followed a consistent wavelike pattern (p < 0.05 and p <
0.0001). Both, eNOS and iNOS, showed their maximum of expression
especially on Day 5 of diestrous and during estrous, when the
highest levels of either progesterone or estrogen were measured. In
the PGF2a-induced cycle, a significant connection between eNOS and
progesterone was proved (p < 0.05). There was a positive
correlation between the expression of the eNOS-mRNA and the uterine
blood flow (p < 0.05) in the control cycle. In the PGF2a-induced
cycle these two parameters also showed a similar cyclic pattern.
The levels of estrogen-receptors in the endometrium or
concentrations of estrogen in plasma were not related to the
endometrial NO-synthases or to TAMV values. Plasma concentrations
of nitrate were independent from the stage of estrous cycle and
consequently were proved as unsuitable for the question raised here
(in this case). The application of the NO donor ISDN leaded to a
marked decrease of the uterine NOS-expression when compared with
control cycle (p < 0.0001). An increase of uterine or ovarian
perfusion during the application of ISDN was not provable (p >
0.05). In result of the biopsies on day 5 and of simultaneous ISDN
application luteolysis was induced next to all mares. On day 15 of
pregnancy, an increase in uterine and ovarian perfusion as well as
an enhancement in iNOS-mRNA expression was observed. In conclusion,
the results of this study indicate that the endometrial
NO-synthases play an important role in the regulation of uterine
blood supply during estrous cycle and pregnancy of the mare.
Progesterone as well as estrogen seem to stimulate the endometrial
expression of eNOS and iNOS, by which these hormones may indirectly
influence uterine and ovarian blood flow.
uterine NOS-system and the sexual steroids estrogen and
progesterone on the blood supply of the uterus and the ovaries.
Five trotter mares were examined in total during four estrous
cycles and one early pregnancy. The investigations contained color
Doppler- and ultrasound recordings as soon as the extraction of
blood samples and endometrial biopsies. The first cycle was
medically uninfluenced and investigations were carried out on Days
0 (= ovulation), 1, 5, 11, 15 and daily during estrous, whereas in
estrous only one endometrial biopsy was taken. In the second cycle
luteal regression was induced on Day 5 of diestrous with the
PGF2α-analogon Tiaprost (Ilirenâ, 450 mg i.m.) and in estrous
ovulation was induced with hCG (Choriolutinâ, 2500 IE i.v.), when
the size of one follicle reached 35 mm. Investigations were carried
out in this cycle immediately before giving PGF2α and 0.5, 1, 3, 6,
12, 24, 36, 48 hours after that and then once a day up to
ovulation. Endometrial biopsies were taken in each case before
induction of luteolysis, 12 and 36 hours after that, before
injection of hCG and immediately after ovulation. During the
further two cycles the mares were treated orally with the NO donor
ISDN (ISDN 40â, 30 mg, twice a day). Investigations were carried
out on Days 0, 1 and 5 of the first cycle (ISDN I), as well as on
Days 11, 15 and during estrous of the second cycle (ISDN II).
During early pregnancy color Doppler recordings and blood samples
were taken on Days 0, 1, 5, 11 and 15 of pregnancy, while
endometrial biopsies were only gained on day 15. The analysis of
uterine blood flow was based on the time-averaged maximum velocity
(TAMV). Estrogens and progesterone were measured by an enzyme
immunoassay. Nitrate concentrations were evaluated using Griess
reacting. Total RNA was isolated from endo-metrial biopsies.
Transcriptes encoding the estrogen receptors a and b and the
endothelial as well as the inducible nitric oxide-synthase (eNOS
and iNOS) were quantified by RT-PCR-analysis. The expression of
eNOS-mRNA in control, as well as in the PGF2a-induced cycle,
followed a consistent wavelike pattern (p < 0.05 and p <
0.0001). Both, eNOS and iNOS, showed their maximum of expression
especially on Day 5 of diestrous and during estrous, when the
highest levels of either progesterone or estrogen were measured. In
the PGF2a-induced cycle, a significant connection between eNOS and
progesterone was proved (p < 0.05). There was a positive
correlation between the expression of the eNOS-mRNA and the uterine
blood flow (p < 0.05) in the control cycle. In the PGF2a-induced
cycle these two parameters also showed a similar cyclic pattern.
The levels of estrogen-receptors in the endometrium or
concentrations of estrogen in plasma were not related to the
endometrial NO-synthases or to TAMV values. Plasma concentrations
of nitrate were independent from the stage of estrous cycle and
consequently were proved as unsuitable for the question raised here
(in this case). The application of the NO donor ISDN leaded to a
marked decrease of the uterine NOS-expression when compared with
control cycle (p < 0.0001). An increase of uterine or ovarian
perfusion during the application of ISDN was not provable (p >
0.05). In result of the biopsies on day 5 and of simultaneous ISDN
application luteolysis was induced next to all mares. On day 15 of
pregnancy, an increase in uterine and ovarian perfusion as well as
an enhancement in iNOS-mRNA expression was observed. In conclusion,
the results of this study indicate that the endometrial
NO-synthases play an important role in the regulation of uterine
blood supply during estrous cycle and pregnancy of the mare.
Progesterone as well as estrogen seem to stimulate the endometrial
expression of eNOS and iNOS, by which these hormones may indirectly
influence uterine and ovarian blood flow.
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