There were no detectable differences in the responses to p3 and рЗТшб when administered at 300 (xg/day. Both proteins were able to extend CL life span when administered at 60 (xg/day. The mean duration of CL life span for those ewes receiving 60 |xg/day of рЗТшб was numerically lower but was not different statistically from CL life span of those ewes in other ovIFN-т treatments, possibly because of low animal numbers within treatments. asthma inhalers
Five ewes receiving intrauterine injections of either 60 jig/day (n = 2) or 300 fxg/day (n = 2) of p3 or 300 (xg/ day (n = 1) of рЗТшб maintained serum progesterone concentrations that were higher than 1 ng/ml in their serum for at least 27 days after cessation of treatment (Day 45 postestrus), at which time they were killed. Postmortem assessment of ovaries from these ewes verified that the ink-marked CLs present during the experimental period were maintained in all five ewes.
Abundance of mRNA for Uterine Serpin after Intrauterine Injection of ovIFN-ts
The abundance of mRNA for the progesterone-dependent gene, uterine serpin , was assessed in endometrium from the five ewes that had not demonstrated a return to estrus at 45 days postestrus. This experiment was conducted in order to determine whether intrauterine injection of ovIFN-ts, irrespective of the form of ovIFN-т administered, had induced a state resembling pseudopregnancy . In pregnant ewes, the mRNA for the uterine serpin could first be detected by Day 25 (Fig. 3). Similar ontogeny of uterine serpin gene expression during pregnancy has been reported previously . Uterine serpin mRNA was detectable in all five ovIFN-T-treated ewes that had not returned to estrus by Day 45. Concentrations of serpin mRNA was comparable to those noted at Day 25 of pregnancy (Fig. 3).
FIG. 3. Northern blot analysis of total RNA from endometrium derived from ewes that did not return to estrus by Day 45 postestrus. Total RNA (20 |ixg), denatured with glyoxyl/dimethyl sulfoxide, was separated by electrophoresis in a 1.2% (w:v) agarose gel and transferred to a nylon membrane. Controls included total RNA from liver and endometrium derived from nonpregnant ewes at Day 10 and Day 13 of the cycle and from ewes at Day 16, Day 25, and Day 45 of pregnancy. The membrane was sequentially hybridized to 32P-labeled cDNAs for ovine uterine serpin and for ovine actin.