The present article shows for the first time that two cell lines derived respectively from a rat
glioma (C6 cell line) and from a human
astrocytoma (1321N1 cell line) are able to convert
testosterone and
progesterone into their corresponding 5 alpha-reduced metabolites
dihydrotestosterone and
dihydroprogesterone. Moreover, both cell lines are also able to convert these metabolites further into their corresponding 3 alpha-
OH derivatives, 5 alpha-androstan-3 alpha, 7 beta-diol (3 alpha-diol) and tetrahydroprogesterone. On the basis of these observations, the possibility that secretory products of normal and tumoral brain cells might be able to influence
steroid metabolism occurring in the two glial cell lines previously mentioned as well as in fetal rat neurons and in neonatal rat type 1 astrocytes has been considered. To this purpose, cultures of the different cellular types have been exposed to the
conditioned medium in which the other cells were grown. The results obtained indicate that: 1. Neurons are able to stimulate, in a statistically significant fashion, the formation of
dihydrotestosterone (DHT), 3 alpha-diol, and tetrahydraprogesterone (THP) in C6 cells. 2. Type 1 astrocytes, on the contrary, are unable to modify
steroid metabolism in C6 cells. 3. C6 cell product(s) decrease(s) the formation of DHP in type 1 astrocytes, without modifying that of DHT. 4. C6 cells do not influence the metabolism of
testosterone (T) and
progesterone (P) in neurons. In conclusion, the present observations show that the
conditioned medium of normal neurons is able to increase the metabolism of
testosterone and
progesterone occurring in a tumoral glial cell line, and that the
conditioned media of the two tumoral cell lines analyzed are able to decrease the conversion of P into DHP occurring in normal type 1 astrocytes. The surprising result that these
conditioned media do not alter the formation of DHT is discussed. Work is presently in progress to identify the principle(s) responsible respectively for the activating and inhibiting actions here described.