Effect of the variations of female sex hormones during the menstrual cycle upon serum somatomedin and growth-promoting activity

Abstract

Serum growth-promoting activity measured upon lymphocytes, sulfation activity and radioimmunoassayable somatomedin C (Sm-C) levels were measured in sera from women during the menstrual cycle. The data showed that: estradiol, progesterone, LH or FSH added in vitro do not increase the 3H-thymidine uptake into lymphocytes; the serum thymidine activity decreases during the luteal stage of the cycle, and is negatively correlated with the progesterone levels; the sulfation factor and Sm-C levels do not have significant variations during the menstrual cycle, and the GH maximum values are attained during the luteal stage.

PIP: This study investigated variations in thymidine activity, sulfation activity, and radioimmunoassayable somatomedin C levels during the menstrual cycle and the direct effect of female sex hormones on 3H-thymidine incorporation into lymphocytes in vitro. Subjects included 8 healthy women 24-46 years of age from whom a total of 49 venous blood samples were obtained. Estradiol, progesterone, luteinizing hormone, or follicle stimulating hormone added in vitro did not increase 3H-thymidine uptake into lymphocytes. The serum thymidine activity level was observed to decrease during the luteal phase of the menstrual cycle and was negatively correlated with the progesterone levels. The sulfation factor and somatomedin C levels did not have significant variations during the menstrual cycle. Finally, growth hormone maximum values were attained during the luteal phase. The negative correlation of thymidine activity levels with progesterone values suggests that more than one thymidine activity measures all serum factors.