Persistence of luteal activity in the non-pregnant ewe
1984; Elsevier BV; Volume: 7; Issue: 1-3 Linguagem: Inglês
10.1016/0378-4320(84)90038-1
ISSN1873-2232
AutoresL. Zarco, G. H. Stabenfeldt, H. Kindahl, J. F. Quirke, Elisabeth Granström,
Tópico(s)Reproductive System and Pregnancy
ResumoFour cases of spontaneous persistence of the corpus luteum (CL) in the ewe are presented along with data concerning normal luteolysis in two ewes. The persistence of the CL in the four ewes resulted in oestrous cycle lengths of 26, 56, 139 and 145 days. Daily plasma levels of progesterone, 15-keto-13,14-dihydro-PGF2α and 11-ketotetranor PGF compounds are reported. In addition, blood samples were taken at two h intervals during the initial prolongation of the CL in two of the ewes. In these ewes, pulsatile release of PGF2α occurred at the expected time, and the release of PGF2α during each pulse, as well as total release from the first to the last pulse, were similar to those of ewes undergoing normal luteolysis. However, the interval between individual pulses was greatly increased in ewes with persistence of the CL, having means of 18.0 h and 18.5 h for two of the ewes sampled intensively. In contrast, two ewes undergoing normal luteolysis had interpulse intervals of 6.8 and 7.2 h, respectively. The results suggest that spontaneous persistence of the CL in the ewe is not due to a primary inability of the uterus to produce PGF2α. A disturbance of the system which acutely controls individual pulses of PGF2α (and thus their frequency) seems to be a more likely cause for the malfunction. In all four cases, the prolonged luteal phase was finally terminated by active release of PGF2α.
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