Plasma kisspeptin levels in lactational amenorrhea

Abstract

The kisspeptin is a neuropeptide to play physiological roles in regulating gonadotropin-releasing hormone secretion in the hypothalamus. In human plasma, the kisspeptin concentration is measured, but gonadotropin-releasing hormone is not. This study aims to understand the physiological roles of the circulating kisspeptin in lactational amenorrhea in humans because prolactin reduces the kisspeptin expression and luteinizing hormone secretion resulting in anovulations in rodent brains. Plasma kisspeptin levels were measured in 11 subjects in lactational amenorrhea and in four cases with pathological amenorrhea by different etiologies for comparison using the enzyme immunoassay specific for human kisspeptin. The plasma kisspeptin levels in the 11 women with lactational amenorrhea were 15.2 ± 2.5 fmol/mL (mean ± SD) which were not significantly different as compared with 16.5 ± 4.8 fmol/mL (mean ± SD) in four age-matched women with menstrual cycles as we reported previously. In the four cases with pathological amenorrhea, their plasma kisspeptin levels were from 5.8 to 13.7 fmol/mL. This study demonstrated that the plasma kisspeptin levels were not totally reduced in lactational or pathological amenorrhea. These results suggest the physiological roles of the circulating kisspeptin are different from the role in the brain.

Chinese abstract

kisspeptin是一种神经肽, 在调节下丘脑促性腺激素释放激素分泌中发挥生理作用。在人血浆中, 测定了kisspeptin的浓度, 未测定促性腺激素释放激素的浓度。这项研究旨在了解循环的kisspeptin在人类哺乳性闭经患者中的生理作用, 因为泌乳素降低了kisspeptin的表达和黄体生成素的分泌, 导致了啮齿动物脑中的无排卵。我们用人类kisspeptin特异性的酶免疫分析法测定了11例哺乳闭经受试者及4例不同病因的病理性闭经患者的血浆kisspeptin水平, 并进行比较。11名哺乳闭经女性的血浆kisspeptin水平为15.2 ± 2.5 fmol/mL（平均值±标准差）, 和我们之前报道的年龄相匹配的有月经周期的4名患者的16.5 ± 4.8 fmol/mL（平均值±标准差） 比较, 差异无统计学意义。在4例病理性闭经患者中, 他们的血浆kisspeptin水平为5.8〜13.7 fmol/mL。这项研究表明, 在哺乳或病理性闭经期间, 血浆kisspeptin水平并未完全降低。这些结果提示循环中的kisspeptin的生理作用不同于在大脑中的作用。

Keywords:

• Amenorrhea
• gonadotropin-releasing hormone
• kisspeptin
• lactation prolaction

Acknowledgements

The authors thank Ms. Chikako Kotani in Asahina Shinryoujo for her secretarial work. This study was supported by Grant-in-Aid for Scientific Research (22790172) from the JSPS and Research Grants from Takeda Science Foundation.

Disclosure statement

No potential conflict of interest was reported by the authors.