- HENRY DRM'IKIUGUMUTEMBEI. "MP Kowalewski, HM Mutembei, B Hoffmann 2006: Expression of Prostaglandin sythetase in the corpus luteum of the dog. Reprod Dom Animal 41 (Suppli.1): 21.". In: Animal Reproduction Science 109 (2008) 319. Elsevier; 2006.
PGFR plays a critical role in determining luteal sensitivity to the luteolytic actions of PGF2a. In the dog the luteal life span can be terminated by exogenous application of PGF2a or its analogues. However, relatively high dosages or repeated treatments are necessary and strong side effects may be observed. In the dog, in contrast to ruminants and other species, luteolysis is not affected by hysterectomy. These observations led to the conclusion that rather paracrine/ autocrine mechanisms than endocrine mechanisms of PGF2a are responsible for luteal regression in the dog. The present experiments were designed to test for the capacity of canine CL to produce and respond to PGF2a. PGFS and PGFR from canine CL from days 5,15, 25, 35, 45, 65 after ovulation were isolated and cloned. A full length PGFS cDNA isolate contains an open reading frame (ORF) of 975 bases coding for a protein of 325 amino acids. The ORF of PGFR consists of 1101 nucleotides encoding a 367 amino acid protein. Both genes show a high homology (82-94%) compared to other species. Relatively weak PGFR mRNA expression was detected on day 5. It had increased by day 25 and remained constant thereafter. In situ hybridization analysis localized the PGFR to the cytoplasm of the luteal cells only, suggesting that those cells are the only targets of PGF2a in this species. Only negative results were obtained when testing for the expression of PGFS by RT-PCR. These data demonstrate that canine CL does not have the capacity to produce PGF2a by PGFS and suggest that luteal regression in non-pregnant bitches is not modulated by PGF2a. However, the PGFR seems to be constitutionally expressed, explaining the receptivity of canine Cl to exogenous PGF2a.