The present study was conducted in order to verify the efficacy of lower doses and alternative routes of a prostaglandin F2 alpha analogue, luprostiol (PGF), for the induction of luteolysis and the precipitation of estrus in nonlactating Nelore cows (Bos taurus indicus). A conventional dose (15 mg) of PGF was compared to doses lower than the conventional dose, which ranges from 10 to 50%, that were administered intramuscularly (IM), intravulvosubmucosally (IVSM), or in the Bai-hui acupuncture site located within the lumbosacral area. The cows were administered PGF 8 day after estrus in the presence of a corpus luteum, and randomly assigned to the following groups: G1 (positive control), 15 mg, IM (n = 23); G2, 7.5 mg, IM (n = 23); G3, 3.75 mg, IM (n = 24); G4, 7.5 mg, IVSM (n = 25); G5, 3.75 mg, Bai-hui acupoint (n = 24); and G6, 1.5 mg, Bai-hui acupoint (n = 25). The results indicated that 50% of a conventional dose of PGF (7.5 mg) resulted in a complete luteal regression (plasma progesterone <1 ng/ml) at Hour 48, and hastened estrus, regardless of whether or not PGF was administered IM or IVSM. Comparatively, 10 or 25% of the conventional dose, even when administered to the Bai-hui acupoint, resulted in an initial reduction in the concentration of progesterone at Hour 24, followed by an increase observed at Hour 48. In conclusion, 25% of a conventional PGF dose administered via the Bai-hui acupoint proved inadequate to induce a complete luteal regression, whereas 50% of a conventional dose administered IM or IVSM was found to be the minimal dose required to induce effectively a complete luteal regression, and to precipitate the onset of estrus in nonlactating Nelore cows.
Acupuncture ; Animals ; Cattle/*physiology ; Dose-Response Relationship, Drug ; Female ; Injections, Intramuscular/veterinary ; Luteolysis/*drug effects ; Progesterone/blood ; Prostaglandins F, Synthetic/*administration & dosage

Endocrine hormones are important factors in maintaining pregnancy as well as initiation of parturition. Progesterone is the major hormone maintaining myometrium quiescence, while glucocorticoids, prostaglandins and estrogen are among the major hormones involved in the initiation of parturition. Therefore progesterone withdrawal at the end of pregnancy is the prerequisite for the initiation of parturition. However, unlike most of the other species of mammals that the withdrawal of progesterone is achieved via reduction of progesterone synthesis or increased conversion of progesterone to estrogen, some mammals including the primates maintain high progesterone level throughout gestation and even during parturition. Accumulating lines of evidence indicate that the withdrawal of progesterone in human being is attained via the changes of the expression ratio of progesterone receptor subtypes and the changes of co-activators required for the activation of transcriptional activity of progesterone receptor. Here we reviewed the three major mechanisms, namely luteolysis, upregulation of placental P450c17 hydroxylase and changes of progesterone receptor functions, underlying progesterone withdrawal in late pregnancy in mammals.
Animals ; Female ; Humans ; Luteolysis ; physiology ; Parturition ; metabolism ; physiology ; Pregnancy ; Pregnancy Trimester, Third ; metabolism ; physiology ; Progesterone ; metabolism ; Receptors, Progesterone ; metabolism ; physiology ; Species Specificity ; Steroid 17-alpha-Hydroxylase ; metabolism

Macrophages in the corpus luteum have many important roles during the periods of functional development and luteal regression. Not only phagocyte the apoptotic luteal cells, but also they secrete many cytokines and exert their effects via autocrine/paracrine actions.In this study, we investigated the changes of number and immunoreactivity of macrophages at various developmental periods of the corpus luteum in the rat ovary. The rats (Sprague-Dawley strain, female)at age of 8 weeks (ovulatory period), GD 6 (pregnant period), and postpartum 5 days (postpartum period)were sacrificed under ether anesthesia and obtained both ovaries, one used for macrophages immunohistochemistry and the other used for TEM. The results were as follows; 1.In the corpora lutea of the rat, macrophages were observed all the developmental periods including ovulatory, pregnant and postpartum periods. 2.In the corpora lutea of the rat, number of macrophages was highest in the ovulatory period, and decreased at postpartum period and pregnant period in order. The immunoreactivity of macrophages was high at ovulatory period, moderate at postpartum period, and low at pregnant period. 3.In TEM observations, two types of macrophages were observed: One type was non-phagocytic macrophage and the other type was phagocytic macrophage. Phagocytic macrophages were observed in the corpora lutea at ovulatory and postpartum periods and contained apoptotic bodies, phagocytic vacuoles and many lipid droplets. Non-phagocytic macrophages were observed in the corpora lutea at pregnancy period and showed slender cell body with long cytoplasmic processes and contained no apoptotic bodies. In the rat, the number and the degree of immunoreactivity of macrophages in the corpus luteum varied with the changes of functional state of the corpus luteum. It was suggested that the main function of the macrophages at the ovulatory and postpartum periods was elimination of apoptotic luteal cells and that at pregnancy period was autocrine/paracrine action.Ultrastructurally, two types, phagocytic and nonphagocytic types, of macrophages confirmed. These results will provide valuable informations on the study of the role macrophages during development and regression of corpus luteum.
Anesthesia ; Animals ; Apoptosis ; Corpus Luteum* ; Cytokines ; Cytoplasm ; Ether ; Female ; Immunohistochemistry ; Luteal Cells ; Luteolysis ; Macrophages* ; Ovary ; Phagocytes ; Postpartum Period ; Pregnancy ; Rats* ; Vacuoles

OBJECTIVE: Our object is to evaluate the detailed mechanisms of support and regression of the human corpus luteum. METHODS: To investigate the regulation of luteal function by gonadotropins, cytokines, and prostaglandins, the frequency of apoptosis and expression of Fas, Fas-L, Bcl-2, Bax, p53, caspase-8 were examined in cultured human luteal cells after treatment with various doses of FSH (30, 100, or 300 ng/mL), LH (30, 100, or 300 ng/mL), TGFbeta1 (1, 10, or 100 ng/mL), TNFalpha (1, 10, or 100 ng/mL), or PGF2alpha (1, 10, or 100 ng/mL) for 24 h. Cells were tested for apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick end labeling TUNEL) method and cell death detection ELISA. Immunostaning was performed using anti-Fas, Fas ligand, Bcl-2, Bax, and p53 antibodies. RESULTS: Incidence of apoptosis determined by TUNEL method in the group without treatment was 1.7+/-0.5% (0 h), 10.8+/-1.6% (24 h), and 12.9+/-1.2% (48 h), respectively. Spontaneous increase was significant at the latter time points. Significant suppression of incidence of apoptosis was observed with LH and TGFbeta1 (P<0.05). On the other hand, significant induction of incidence of apoptosis was observed with TNFalpha and PGF2alpha (P<0.05). Immunostaining revealed that p53 and Bax expressions after treatment with LH or TGFbeta1 were significantly lower than those without treatment. Bcl-2 and caspase-8 expressions were not significantly affected by any substance addition. Also we found that inductions of apoptosis by TNFalpha and PGF2alpha were not correlated with the expression of Fas, Fas ligand, Bcl-2, Bax, p53 and caspase-8. CONCLUSION: Our results suggest that LH and TGFbeta1 may be involved in the support of luteal function via suppression of apoptosis, and that TNFalpha and PGF2alpha may contribute to luteal regression via its induction in human corpus luteum during early luteal phase. Also, Fas, Fas-L, Bax and p53 may play roles in this apoptosis controlled by LH, and TGFbeta1.
Antibodies ; Apoptosis* ; Caspase 8 ; Cell Death ; Corpus Luteum ; Cytokines* ; Deoxyuridine ; Dinoprost ; Enzyme-Linked Immunosorbent Assay ; Fas Ligand Protein ; Female ; Gonadotropins* ; Hand ; Humans* ; In Situ Nick-End Labeling ; Incidence ; Luteal Cells* ; Luteal Phase ; Luteolysis ; Prostaglandins ; Tumor Necrosis Factor-alpha