Wiltbank M C, Guthrie P B, Mattson M P, Kater S B, Niswender G D
Department of Physiology, Colorado State University, Fort Collins 80523.
Biol Reprod. 1989 Oct;41(4):771-8. doi: 10.1095/biolreprod41.4.771.
The second messengers mediating hormonal regulation of the corpus luteum are incompletely defined, particularly for the primary luteolytic hormone prostaglandin F2 alpha (PGF2 alpha). In this study, hormonally induced changes in free intracellular calcium concentrations were measured in individual small and large ovine luteal cells by using computer-assisted microscopic imaging of fura-2 fluorescence. This technique could readily detect transient increases in free calcium concentrations within both small and large luteal cells after treatment with 1 microM of the calcium ionophore, A23187. Treatment with PGF2 alpha (1 microM) caused a dramatic increase in free calcium concentrations in large (before = 73 +/- 2 nM; 2 min after PGF2 alpha = 370 +/- 21 nM; n = 33 cells) but not in small (before = 66 +/- 4 nM; 2 min after PGF2 alpha = 69 +/- 8 nM; n = 12 cells) luteal cells. The magnitude and timing of the calcium response was dose- and time-dependent. The PGF2 alpha-induced increase in free intracellular calcium is probably due to influx of extracellular calcium, since inclusion of inorganic calcium channel blockers (100 microM manganese or cobalt) attenuated the response to PGF2 alpha and removal of extracellular calcium eliminated the response. In contrast to PGF2 alpha, luteinizing hormone (LH) (100 ng/ml) caused no change in intracellular levels of free calcium in small or large luteal cells, even though this dose of LH stimulated (p less than 0.01) progesterone production by small luteal cells. Therefore, alterations in free calcium concentrations could be the intracellular second message mediating the luteolytic action of PGF2 alpha in the large ovine luteal cell.
介导黄体激素调节的第二信使尚未完全明确，尤其是对于主要的黄体溶解激素前列腺素F2α（PGF2α）而言。在本研究中，通过使用计算机辅助的fura-2荧光显微成像技术，测量了单个小的和大的绵羊黄体细胞中激素诱导的细胞内游离钙浓度的变化。该技术能够很容易地检测到用1微摩尔钙离子载体A23187处理后，小的和大的黄体细胞内游离钙浓度的瞬时增加。用PGF2α（1微摩尔）处理导致大的黄体细胞（处理前 = 73 ± 2纳摩尔；PGF2α处理后2分钟 = 370 ± 21纳摩尔；n = 33个细胞）内游离钙浓度显著增加，但小的黄体细胞（处理前 = 66 ± 4纳摩尔；PGF2α处理后2分钟 = 69 ± 8纳摩尔；n = 12个细胞）内则未增加。钙反应的幅度和时间是剂量和时间依赖性的。PGF2α诱导的细胞内游离钙增加可能是由于细胞外钙的内流，因为加入无机钙通道阻滞剂（100微摩尔锰或钴）可减弱对PGF2α的反应，而去除细胞外钙则消除该反应。与PGF2α相反，促黄体生成素（LH）（100纳克/毫升）在小的或大的黄体细胞内均未引起游离钙水平的变化，尽管该剂量的LH刺激（p < 0.01）了小黄体细胞的孕酮生成。因此，游离钙浓度的改变可能是介导PGF2α在大的绵羊黄体细胞中黄体溶解作用的细胞内第二信使。
