title: Differential regulation of apoptosis in the corpus luteum of pregnancy and newly formed corpus luteum after parturition in rats.
abstract: Apoptosis contributes to luteal regression in many species. In the postpartum rat, there are two different types of corpora lutea (CL) in the ovary: CL of pregnancy (CLP) and newly formed CL (NCL). To investigate the regulation of apoptosis in the two different types of CL during luteal regression, apoptosis and caspase-3 activity were examined in the CL obtained on Days 7, 15, and 21 of pregnancy and Days 0, 1, 3, 5, 7, and 9 postpartum. Furthermore, the effect of lactation on apoptosis in the CL was examined in two groups of postpartum rats: lactating rats that nurse more than 10 pups, and nonlactating rats that nurse no pups. Apoptotic cells were detected after Day 21 of pregnancy. In the CLP, remarkable increases in the number of apoptotic cells on Days 5 and 9 postpartum were observed in nonlactating rats (P < 0.01), but not in lactating rats. Changes in caspase-3 activity in the CLP were not consistent with those in number of apoptotic cells. In the NCL, an increase in apoptosis was found only on Day 5 postpartum in nonlactating rats (P < 0.01), but not in lactating rats. Changes in caspase-3 activity in the NCL were consistent with those in number of apoptotic cells. In conclusion, apoptosis is, at least in part, involved in luteal regression after parturition, and lactation appears to inhibit apoptosis. This study also suggests the presence of a caspase-3-independent mechanism for apoptosis in CLP regression in the rat.
authors.affiliation: Department of Reproductive, Pediatric, and Infectious Science, Yamaguchi University School of Medicine, Yamaguchi 755-8505, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Takiguchi
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sugino
authors.forename: Kikue
authors.initials: K
authors.lastname: Esato
authors.forename: Ayako
authors.initials: A
authors.lastname: Karube-Harada
authors.forename: Aki
authors.initials: A
authors.lastname: Sakata
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kato
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003338:Corpus Luteum / Q000166:cytology* / Q000502:physiology*; D005260:Female; D007774:Lactation; D008098:Litter Size / Q000502:physiology; D003341:Luteolysis / Q000502:physiology*; D008297:Male; D009929:Organ Size; D036801:Parturition; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases