Steinetz B G, Goldsmith L T, Hasan S H, Lust G
New York University Medical Center, Laboratory for Experimental Medicine and Surgery in Primates, Tuxedo, New York 10987.
Endocrinology. 1990 Sep;127(3):1057-63. doi: 10.1210/endo-127-3-1057.
The concentrations of progesterone (P), relaxin (Rlx), estradiol (E2) and PRL were measured by specific RIAs in serum samples collected twice daily at 8:00 am and 3:00 pm at weekly intervals after mating and until whelping in five Labrador Retriever bitches. From weeks 3 to 6 of pregnancy, P exhibited a conspicuous and statistically significant diurnal pattern (P less than 0.05), its serum concentration being approximately twice as high at 8:00 am as at 3:00 pm. A similar but nonsignificant trend was observed weeks 2, 7, and 8, and the overall ratio of the am/pm P concentrations was 2.4 +/- 0.28 (P less than 0.001). Rlx, E2, and PRL did not show a diurnal pattern at any time during pregnancy. The glandular sources and regulation of secretion of Rlx were further investigated. Rlx bioactivity was detected in canine placentas and ovaries, providing supportive evidence that these organs may be a dual source of the hormone in canine pregnancy. Injection of ovine PRL in three pseudopregnant bitches significantly increased serum P concentration as compared with seven untreated pseudopregnant controls, but Rlx was not detectable in serum before, during or after PRL treatment. The data support the view that Rlx and P are independently regulated in the bitch; PRL may be a regulator of P, but not of Rlx secretion. However, as PRL showed no diurnal changes in concentration, it does not appear to be directly responsible for the diurnal pattern exhibited by P.
在五只拉布拉多母犬交配后至分娩期间，每周一次于上午8:00和下午3:00每天采集两次血清样本，通过特异性放射免疫分析法（RIAs）测定孕酮（P）、松弛素（Rlx）、雌二醇（E2）和催乳素（PRL）的浓度。在妊娠第3至6周，P呈现出明显且具有统计学意义的昼夜节律模式（P<0.05），其血清浓度在上午8:00约为下午3:00的两倍。在第2、7和8周观察到类似但无统计学意义的趋势，上午/下午P浓度的总体比值为2.4±0.28（P<0.001）。在妊娠期间的任何时候，Rlx、E2和PRL均未表现出昼夜节律模式。进一步研究了Rlx的腺体来源和分泌调节。在犬胎盘和卵巢中检测到Rlx生物活性，为这些器官可能是犬妊娠期间该激素的双重来源提供了支持性证据。与七只未处理的假孕对照相比，给三只假孕母犬注射羊PRL显著增加了血清P浓度，但在PRL治疗前、治疗期间或治疗后血清中均未检测到Rlx。这些数据支持了母犬中Rlx和P受独立调节的观点；PRL可能是P的调节因子，但不是Rlx分泌的调节因子。然而，由于PRL浓度未表现出昼夜变化，它似乎不是P所呈现的昼夜节律模式的直接原因。
