Luz Marcelo Rezende, Bertan Claudia Maria, Binelli Mario, Lopes Maria Denise
CCA, Department of Animal Science and Rural Economy, Federal University of Espírito Santo-UFES, Alto Universitário, Caixa Postal 16, CEP 29.500-000, Alegre, ES, Brazil.
Theriogenology. 2006 Oct;66(6-7):1436-41. doi: 10.1016/j.theriogenology.2006.01.036. Epub 2006 Feb 7.
The canine corpus luteum (CL) typically sustains elevated plasma progesterone concentrations for 2 months or more, with a peak approximately 15-25 days after ovulation, followed by a slow decline. The processes involved in the slow, protracted regression of the CL over the remaining 1.5-2-month period in nonpregnant bitches and until shortly prepartum in pregnant bitches are not well characterized. The rapid luteolysis that occurs immediately prepartum appears to be a result of a prepartum rise in peripheral PGF. The potential role of PGF in the slow regression process in the several weeks preceding parturition and in nonpregnant bitches after 15-25 days after ovulation is not known. Therefore, plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F2-alpha (PGFM), progesterone (P4) and estradiol (E2) were determined and compared in bitches during nonpregnant diestrus (n = 9) or pregnancy (n = 8). During the gradual decrease in plasma concentrations of progesterone in both groups, the P4 pattern appeared unrelated to changes in either E2 or PGFM concentrations. The PGFM pattern was different between diestrus and pregnant bitches (P > 0.01); there was an apparent progressive but slow increase in PGFM in pregnant bitches from Days 30 to 60, followed by a large increase prior to parturition; concentrations declined immediately postpartum. However, there were no increases in PGFM during the same interval in nonpregnant bitches. Mean estradiol concentrations were sporadically elevated during the last third of pregnancy and less so in nonpregnant diestrus; there was no acute prepartum increase in estradiol associated with the PGFM increase. In summary, although there were no apparent changes in peripheral PGF2alpha concentration involved in regulating the slow protracted phase of luteal regression in nonpregnant bitches, modest increases in PGFM may play a role in ovarian function after mid-gestation in pregnant bitches. Furthermore, the acute prepartum rise in PGFM was not dependent on any concomitant increase in estradiol concentrations.
犬的黄体（CL）通常可使血浆孕酮浓度维持在较高水平达2个月或更长时间，排卵后约15 - 25天达到峰值，随后缓慢下降。在未怀孕母犬剩余的1.5 - 2个月期间以及怀孕母犬直至产前不久，黄体缓慢、持久退化所涉及的过程尚未得到充分表征。产前立即发生的快速黄体溶解似乎是外周前列腺素F2α（PGF）在产前升高的结果。PGF在分娩前几周以及排卵后15 - 25天的未怀孕母犬的缓慢退化过程中的潜在作用尚不清楚。因此，测定并比较了未怀孕发情后期（n = 9）或怀孕（n = 8）母犬血浆中13,14 - 二氢 - 15 - 酮 - 前列腺素F2α（PGFM）、孕酮（P4）和雌二醇（E2）的浓度。在两组孕酮血浆浓度逐渐下降的过程中，P4模式似乎与E2或PGFM浓度的变化无关。发情后期和怀孕母犬的PGFM模式不同（P > 0.01）；怀孕母犬从第30天到第60天PGFM明显呈渐进性但缓慢增加，随后在产前大幅增加；产后立即下降。然而，未怀孕母犬在相同时间段内PGFM没有增加。平均雌二醇浓度在怀孕最后三分之一期间偶尔升高，在未怀孕发情后期则较少；产前没有与PGFM增加相关的雌二醇急性升高。总之，虽然在调节未怀孕母犬黄体退化的缓慢持久阶段外周PGF2α浓度没有明显变化，但PGFM的适度增加可能在怀孕母犬妊娠中期后的卵巢功能中起作用。此外，PGFM在产前的急性升高并不依赖于雌二醇浓度的任何伴随增加。
