Setchell B P, Pakarinen P, Huhtaniemi I
Pediatric Endocrinology Unit, Karolinska Hospital, Stockholm, Sweden.
J Endocrinol. 2002 Nov;175(2):375-82. doi: 10.1677/joe.0.1750375.
The purpose of this study was to assess the concentrations of LH that Leydig cells are exposed to upon in vivo stimulation of steroidogenesis. The concentrations of LH were measured in rats in testicular interstitial extracellular fluid, seminiferous tubular fluid and blood plasma from testicular veins from one testis before and from the other testis of the same rats after an intravenous injection of gonadotrophin-releasing hormone (GnRH) or saline, and compared with the concentrations in blood plasma from a peripheral vein. The concentrations of LH in interstitial fluid surrounding the Leydig cells before the injections were about 10% of the levels in blood plasma, and showed no significant rise at 15 min and a much smaller rise at later times in rats injected with GnRH than those seen in blood plasma from either of the two sources, which were similar. The concentrations of LH in tubular fluid were even lower and showed no change after GnRH. Testosterone concentrations in testicular cells, interstitial fluid and testicular venous blood plasma were significantly increased by 15 min after GnRH, when compared with saline-injected controls, with no change in the levels in tubular fluid. The rise in testosterone concentrations in testicular venous plasma after GnRH was smaller than those in the cells and interstitial fluid. In conclusion, the concentrations of LH reaching the testicular interstitial fluid were only about one-tenth of that measured in the circulation, presumably because the endothelial cells restrict access of the hormone to the interstitial fluid. This indicated that either the Leydig cells are extremely sensitive to LH stimulation or that testicular endothelial cells modulate the action of LH on the Leydig cells.
本研究的目的是评估在体内刺激类固醇生成时，睾丸间质细胞所接触到的促黄体生成素（LH）浓度。在大鼠静脉注射促性腺激素释放激素（GnRH）或生理盐水前后，分别测量一侧睾丸的睾丸间质细胞外液、曲细精管液和睾丸静脉血浆中的LH浓度，并与外周静脉血浆中的浓度进行比较。注射前，睾丸间质细胞周围间质液中的LH浓度约为血浆浓度的10%，注射GnRH的大鼠在15分钟时无显著升高，随后升高幅度远小于来自上述两种来源的血浆，这两种来源的血浆LH浓度相似。曲细精管液中的LH浓度更低，注射GnRH后无变化。与注射生理盐水的对照组相比，GnRH注射后15分钟，睾丸细胞、间质液和睾丸静脉血浆中的睾酮浓度显著升高，而曲细精管液中的水平无变化。GnRH注射后，睾丸静脉血浆中睾酮浓度的升高幅度小于细胞和间质液中的升高幅度。总之，到达睾丸间质液的LH浓度仅约为循环中测量值的十分之一，推测是因为内皮细胞限制了激素进入间质液。这表明，要么睾丸间质细胞对LH刺激极其敏感，要么睾丸内皮细胞调节LH对睾丸间质细胞的作用。
