Association of tritium-labelled estradiol, progesterone and 17 alpha-hydroxyprogesterone with the proteins of the serum and cerebrospinal fluid in the rhesus monkey.

The electrophoretic profiles of the proteins in the serum and cerebrospinal fluid (CSF) of the rhesus monkey were studied by polyacrylamide gel electrophoresis. The association of tritium labelled estradiol (3H-E), progesterone (3H-P) and 17 alpha-hydroxyprogesterone (3H-17OHP) with these proteins was studied under in vitro and in vivo conditions. The CSF was found to contain, besides albumin, at least 4 globulins with similar electrophoretic mobilities as those found in the serum. The electrophoretic mobilities of these globulins were Ralb 0.4, 0.6, 0.8 and 0.9. The electrophoretic profiles of the monkey serum and CSF proteins were found to be similar to those described for human serum and CSF. 3H-E and 3H-P were respectively associated with serum globulins of Ralb 0.4 and 0.8 both in the in vitro and in vivo studies. The respective Ralb of these 2 globulins were similar to the testosterone-estradiol binding globulin and cortisol binding globulin in human serum. 3H-17OHP was found to be associated with several globulins under both in vitro and in vivo conditions. In marked contrast to the in vitro studies, radioactive products were found to be associated with albumin in vivo. It is presumed that these products may be steroidal conjugates derived from the systemic metabolism of the administered steroids. No radioactivity was associated with the CSF protein after in vitro incubation with any of the three 3H-steroids. In the in vivo studies, however, radioactivity was associated with such of the CSF proteins that were similar to those found in the serum and with which the administered steroids were associated.