Plasma progesterone levels during delayed implantation in the European badger (Meles meles)

Summary. Peripheral plasma progesterone concentrations exhibited an increase 10 days before implantation, coinciding with the resumption of blastocyst growth and with a decrease in plasma androgen values (DHA, androstenedione, testosterone). No definite pattern of oestrone was observed and oestradiol concentrations remained undetectable. The production of steroids by dispersed luteal cells showed that the growth of the corpora lutea paralleled that of blastocysts and resulted in hypertrophy followed by hyperplasia of the luteal cell. The production of progesterone in the medium increased with blastocyst size up to implantation; it was enhanced by mink charcoal-treated serum, but prolactin, LH, FSH or a combination of these hormones did not affect the progesterone production, whatever the stage of diapause. DHA and androstenedione secretion increased in the two last stages of blastocyst growth and was enhanced by LH. The conversion of androstenedione and testosterone into oestrone and oestradiol was observed at all stages of embryonic diapause, indicating that corpora lutea contain aromatase activity even at an early stage. The secretion of oestrone was higher than that of oestradiol. The non-luteal tissue contributed up to 50% of the steroid production; while progesterone and androgen production remained constant, that of oestradiol decreased at the end of the delay period. These results indicated a change in the size and the secretory capacity of the luteal cell related to blastocyst development and implantation. Although progesterone was the main product of the corpora lutea, androgens and oestrogens were also secreted.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Patterns of plasma progesterone, androgen and oestrogen concentrations and in-vitro ovarian steroidogenesis during embryonic diapause and implantation in the mink (Mustela vison)

Stoufflet¹,

Mondain-Monval²,

Simon³

et al. 1989

“…armadillo (Labhsetwar & Enders, 1968;Peppier & Stone, 1976), stoat (Gulamhusein & Thawley, 1974), European badger (Bonnin et al, 1978), spotted skunk (Mead, 1981), northern fur seal (Daniel, 1981) and black bear (Foresman & Daniel, 1983), the corpora lutea are less active during embryonic diapause, and the plasma progesterone concentrations stay slightly above the values in non-pregnant animals until shortly before implantation, when the concentrations begin to increase with activation of the corpora lutea. However, the roe deer, Capreolus capreolus, is unique in having an active corpus luteum throughout the diapause period, although no significant change is detected in the progesterone concentration until after implantation (Hoffman et al, 1978;Aitken, 1981).…”

Section: Discussionmentioning

confidence: 99%

Changes in progesterone concentrations in the Japanese long-fingered bat, Miniopterus schreibersii fuliginosus

Kimura¹,

Takeda²,

Uchida³

1987

Summary. In the Japanese long-fingered bat, when compared with the baseline values during non-pregnancy in the autumn, plasma progesterone concentrations were not significantly elevated during the delayed implantation stage that begins before the bats enter hibernation. However, progesterone concentrations were significantly lower during the delayed development stage that occurs during hibernation and rose significantly during the rapid embryogenesis that occurs after arousal from hibernation in the spring. Changes in the corpus luteum volume corresponded closely with those of plasma progesterone values. Maintenance of gravid females at 25\s=deg\Cfor 2 weeks in winter resulted in significant increases in the plasma progesterone concentration and the corpus luteum volume.

“…The increase in plasma progesterone values clearly reflected reactivation of the corpus luteum and is very similar to the response observed by Tyndale-Biscoe & Hinds (1981 during the period of natural reactivation of the corpus luteum around the summer solstice. In eutherians exhibiting embryonic diapause, including the spotted skunk (Mead & Eik-Nes, 1969), badger (Bonnin, Canivenc & Ribes, 1978) and mink (Meiler, 1973;Allais & Martinet, 1978), the termination of diapause is associated with secretion of progesterone by the newly active corpus luteum. Moreover, for mink subjected to a 14L:10D photoperiod (Allais & Martinet, 1978) and for badgers placed in an artificial winter photoperiod (Canivenc & Bonnin, 1979), the period of diapause was shortened and, after the change in photoperiod, plasma progesterone levels were similar to those observed at the normal time of implantation and during pregnancy.…”

Section: Discussionmentioning

confidence: 99%

Effect of changing photoperiod on peripheral plasma prolactin and progesterone concentrations in the tammar wallaby (Macropus eugenii)

Hinds¹,

Ottolander²

1983

Summary. In tammar wallabies kept in normal daylengths between the equinoxes, births occurred at the normal time after the summer solstice and the progesterone profile reflected this cycle. There were no significant changes in plasma prolactin. In tammars placed in a 15L : 9D photoperiod and then, 5 weeks later, in 12L :12D, births occurred 29\p=n-\36 days after the daylength was reduced. A characteristic transient peak of plasma progesterone occurred 8\p=n-\14 days after the change, indicating a delay of 3\p=n-\9 days in the resumption of luteal activity. Plasma prolactin levels were significantly higher (> 40 ng/ml) (P < 0\m=.\01)during the solstitial daylength, declining to <30 ng/ml within 14 days of the reduction in photoperiod. Animals kept in 12L : 12D and then in 9L :15D gave birth asynchronously after entry into the pens, suggesting that this daylength (12L:12D) is permissive. Changes in plasma progesterone reflected the resumption of luteal activity but no significant changes in plasma prolactin were observed.This study shows that the inhibition of the corpus luteum in seasonal quiescence can be maintained in the presence or absence of elevated prolactin levels, indicating that other factors, perhaps of pineal origin, may also be involved.