The LH hybridization signal was less in whole ovaries after luteal activation and during postimplantation gestation. In whole ovaries, bromocriptine treatment not only that were killed on April 5, and all from April 10 and 15, had uterine swellings containing embryos. Calculated dates of implantation in the control group ranged from March 31 to April 8. Although blastocysts were present in bromocriptine-treated mink at each of the collection dates, none were expanded or showed any indication of resumption of development. flovent inhaler
Abundance of Prolactin and LH Receptor Transcripts and Prolactin Binding during Gestation
The abundance of transcripts that hybridized with the mink prolactin receptor probe did not differ in ovaries collected between March 19 and March 29, in spite of the activation of the CL through this period. Thereafter, the prolactin receptor mRNA levels increased 3-fold between March 29 and April 15 (Fig. 2, A and B, p < 0.05). These findings were confirmed in samples of CL dissected from the ovaries during diapause and postimplantation, showing that there was no apparent increase through the time of luteal activation as defined by progesterone levels in excess mRNA present during diapause in ovaries from control animals but also reduced the abundance of LH receptor mRNA to well below the level in pretreated controls (p < 0.05, Fig. 5, B and C). The mean transcript abundance was less in bromocriptine-treated mink within 2 days of the initiation of treatment and remained low thereafter (p < 0.01). There was no apparent difference in LH receptor message abundance from pools of CL taken at diapause (March 21) and activation (March 25), while there was a decline to 30% of diapause levels in CL from postimplantation gestation (Fig. 3).
FIG. 4. Mean ± SEM of 125I-labeled prolactin binding to homogenates of ovaries from pregnant mink collected between March 19 and April 15 (n = 3 per sampling date). Results are expressed as mean ± SEM cpm bound per mg protein.
FIG. 5. A) Mean ± SEM of LH receptor mRNA abundance in ovarian tissue collected from pregnant mink every 3 days between March 19 and March 31 and every 5 days thereafter until April 15 (n = 3 animals per sampling date). B) A representative control Northern blot hybridized with the mink LH receptor probe and rehybridized with the human 28S probe. C) A blot of RNA from the ovaries of bromocriptine-treated animals.