Experiment 2: Hormone Treatments
Ovariectomy significantly (p < 0.05) reduced the plasma concentration of progesterone (1.5 ± 0.8 ng/ml) to below that found during embryonic diapause. Silicone elastomer capsules containing progesterone significantly (p < 0.05) increased plasma progesterone to 22.5 ± 9.3 ng/ml and to 26.3 ± 9.8 ng/ml in the group treated with progesterone plus estradiol. Estrogen was nondetectable in all ovariec-tomized control animals. Silicone elastomer capsules containing estradiol elevated plasma estrogen concentration to 6.3 ± 3.5 pg/ml in the estradiol-treated animals and to 4.7 ± 1.2 pg/ml in the group treated with progesterone plus estradiol. PRL concentration in the diluent-treated control group averaged 17.6 ng/ml. Daily injections of oPRL elevated plasma PRL concentration to 117.1 ± 38.5 ng/ml. buy flovent inhaler
Treatment with either of the steroid hormones significantly increased (p < 0.01) uterine weight (Fig. 4A). Animals treated with estradiol, as well as those treated with estradiol plus progesterone, exhibited a twofold increase in uterine weight over that of ovariectomized controls. Daily injections of PRL or constant infusion of EGF had no significant effect on uterine weight or on blastocyst diameter compared to these values in control animals.
Messenger RNA for LIF was detected in all animals and in every treatment group. Uterine LIF expression in ovari-ectomized control animals was elevated compared to that in uteri of intact animals containing blastocysts in diapause; however, this difference was not statistically significant. There were no significant changes in LIF mRNA abundance in response to PRL or steroid treatments when compared to values in ovariectomized controls (Fig. 4B). LIF mRNA concentration was lowest in the PRL-treated group and highest in the EGF-treated group (data not shown). Although the average LIF/cyclophilin ratio in the EGF-treated animals was identical to that in uteri containing activated blastocysts, the mean value (0.147) was not statistically different from that during delayed implantation, due to the wide range in ratios and small sample size (n = 3) in the EGF-treated group.
FIG. 4. A) Weight of paired uterine cornua (mean ± SEM) from ovari-ectomized skunks receiving diluent and empty capsules (control), PRL injection (Prl), estradiol capsules (E2), progesterone capsules (P4), or a combination of the two steroids (P4 + E2). Number of animals in each group is in parentheses. Means denoted by different letters significantly differ (p = 0.003) from control values. B) Relative abundance of LIF mRNA normalized to cyclophilin (mean ± SEM) in the uterus of ovari-ectomized skunks receiving diluent and empty capsules (control), PRL injection (Prl), estradiol capsules (E2), progesterone capsules (P4), or a combination of the two steroids (P4 + E2). Number of animals in each group is in parentheses. None of the treatment values significantly differed from control values.