PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE, FOLLICLE STIMULATING HORMONE AND PROLACTIN IN OVARIECTOMIZED, HYSTERECTOMIZED AND INTACT SWINE
PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE, FOLLICLE STIMULATING HORMONE AND PROLACTIN IN OVARIECTOMIZED, HYSTERECTOMIZED AND INTACT SWINE
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Date
1974
Authors
Wilfinger, William Walter Jr
Advisor
Brinkley, Howard J.
Citation
DRUM DOI
Abstract
In order to critically evaluate the temporal patterns of plasma
luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin
(PRL); blood samples were collected daily at 0600, 1200, 1800 and 2400 hrs
from intact, sham, ovariectomized and hysterectomized Yorkshire sows via
indwelling vena caval cannulae. The maximum preovulatory plasma LH concentration
in the intact and sham operated swine (mean ±l SD, 7.06±2.40
ng/ml) was reached between 2400 hrs on the first day of estrus (day 0)
and 0600 hrs on day 1. Preovulatory LH peaks averaged 28.75±4.76 hrs
duration from initial rise from, and return to, a baseline concentration
of 1.19±.25 ng/ml plasma. In addition to the preovulatory LH peak, an
average of 8.75 luteal phase peaks was observed during each estrous cycle .
Approximately 69.5% ·of the luteal phase peaks had an average duration of
12.65±1.79 hrs, an average maximum plasma concentration of 2.29±.55 ng/ml
and occurred during days 2 to 17. The remaining luteal phase peaks reached
a maximum concentration of 2.86±1.04 ng/ml and occurred during days
2 to 13. The average duration of these luteal phase peaks was 18.61±
3.49 hrs.
The largest and most consistent plasma FSH peak in the intact and
sham operated swine occurred between days 2 and 3. This postovulatory
peak had a duration of 58.17±16.25 hrs and reached an average maximum
concentration of 13.14±9.42 ng/ml before returning to a baseline of 4.76±
1.56 ng/ml plasma. The initial rise of the postovulatory FSH peak coincided
with the initial rise of the preovulatory LH peak, but did not reach
maximum concentration until 2.66±.45 days after the preovulatory LH peak
had reached maximum concentration. In some animals, a luteal phase FSH
peak occurred between days 8 to 14. The luteal phase FSH peaks had a
duration of 18.09±5.36 hrs and an average maximum concentration of 9.76±
3.78 ng/ml plasma.
An average of 2.58±1.08 plasma PRL peaks was observed between day 0
and day 2 of the estrous cycle in the intact and sham operated swine.
These peaks averaged 20.54±4.02 hrs in duration and reached maximum concentrations
of 11.49±2.97 ng/ml before returning to a baseline of 6.54±
1.29 ng/ml plasma. They reached their maximum concentration approximately
9.12±9.84 hrs after the maximum concentration of the preovulatory LH peak
had been reached. Larger prolactin peaks occurred during the follicular
phase of the estrous cycle. An average of 3.09±1.38 peaks occurred between
days 14 and 19.· These peaks had an average duration of 18.98±3.30
hrs and reached a maximum concentration of 14.28±4.27 ng/ml plasma.
Shortly after removal of the ovaries (6 to 8 hrs), baseline LH (2.2±
.14 ng/ml) and FSH (12.20±2.90 ng/ml) plasma concentrations in the ovariectomized
swine were significantly greater (P<.05) than those found in
the intact and sham operated animals, but baseline prolactin concentrations
(6.70±2.10 ng/ml) were not significantly different (P>.05) from the
controls. The temporal patterns of maximum plasma concentrations associated
with LH (3.47±.21 ng/ml), FSH (21.43±.82 ng/ml) and PRL (9.32±2.00
ng/ml) peaks were not similar among the ovariectomized animals.
Baseline LH (1.12±.34 ng/ml), FSH (5.30±2.09 ng/ml) and PRL (6.05±
1.89 ng/ml) concentrations in the hysterectomized swine were not significantly
different (P>.05) from the baseline concentrations in the intact
and sham operated animals. Numerous plasma LH peaks (14.30±4.59) were
observed during the 20-day collection period. These peaks averaged 19.50
±1.49 hrs in duration and reached maximum concentrations of 2.63±.23 ng/
ml before returning to baseline. Plasma FSH and PRL peaks averaged 21.00
±4.51 and 17,69±3.50 hrs in duration and reached maximum concentrations
of 8.12±1.95 and 10.18±2.95 ng/ml before returning to baseline.
Mean plasma LH concentrations in the intact, sham, ovariectomized
and hysterectomized swine were significantly greater at the 2400 hr
collections than at the 1800 hr collections.
A critical assessment of plasma hormone concentrations is an essential
prerequisite to a basic understanding of the physiological mechanisms
governing the reproductive process. The descriptive data provided by
this study will enable future investigators to design critical experiments
to evaluate the physiological importance of these hormone fluctuations,
thereby broadening our basic understanding of the mechanisms which
govern the reproductive cycle.