The present data show the lack of a significant effect of repeated injections of a mixture of IFN-7 and IFN-S on two parameters indicative of the CL activity in cyclic gilts, i.e., the day of the mid-decrease of progesterone (Figs. IB and 2B) and the inter-estrus interval. Moreover, the duration of the estrous cycle was not shortened by uterine catheters. Indeed, in our herd, the mean duration of the second estrous cycle was 19.1 ±2 days (n = 505, unpublished observations). It is similar to that reported for Meishan gilts in China (19.8 ± 0.2 days, ) and in the United Kingdom (between 19.3 ± 2.3 and 21.4 ± 2.6, ). All these values are very close to that observed in this experiment (19.6 ± 0.55 and 19.0 ± 0.96 days). Buy Asthma Inhalers Online
Our results demonstrate the absence of a “hormonelike” effect of conceptus-derived IFNs per se on cyclic CL.
The IFN doses infused were much (Days 11-13) or significantly (Day 14) higher than natural titers found in pregnant gilts on the corresponding days. It is therefore unlikely that the absence of effect was due to insufficient dosage. Moreover, the lack of an antiluteolytic effect of IFN treatment could not be attributed to an insufficient distribution. Marengo et al. indicated that infusion of PGF2o in a few milliliters of a saline solution just below the utero-tubal junction allowed the material to be distributed throughout the uterine horn. This conclusion was based on results reported previously : a 3% solution of Evans blue dye in 5 ml of 0.9% NaCl was injected into the uterine lumen, just below the utero-tubal junction. After 120 min the gilts were hysterectomized, and the dye was shown to be distributed evenly along the endometrium.