engleski

The Influence of Sex Steroid Hormones on Ganglioside Biosynthesis in Rat Kidney

Castrated male rats were subcutaneously injected testosterone (5 and 10 mg) or a mixture of b-estradiol and progesterone (1 mg + 2 mg), to determine whether sex steroid hormones (testosterone, b-estradiol, progesterone) might affect the content of sialoglyco-proteins, the content and pattern of lipid-bound sialic acid, and the activities of SAT I and SAT II in the Golgi-rich membrane fraction isolated from rat kidney. During four days testosterone did not affect significantly the content of proteins, sialoglycoproteins and total gangliosides, but increased the content of b-series gangliosides from 0.05 ą 0.06 (untreated animals injected subcutaneously with 0.1 ml DMSO for four days) to 0.16 ą 0.02 nmol SA/mg protein (castrated aimals injected subcutaneously with 10 mg testosterone/0.1 ml DMSO for four days). This increase was due to the increase in GD3 ganglioside from 0.03 to 0.12 nmol SA/mg protein, and to the decrease of GM1 ganglioside from 0.06 to 0.03 nmol SA/mg protein by testosterone administration. The major ganglioside in the rat kidney was GM3 comprissing 63 % (control group) and 51 % (castrated animals injected daily with 10 mg testosterone). Castration itself induced an increase in the rat kidney SAT I and SAT II activities from 712 ą 130 to 1723 ą 412 pmol/h x mg protein and from 208 ą 48 to 751 ą 176 pmol/h x mg protein, respectively. However, subsequent administration of testosterone, at the highest concentration tested, reversed this effect. In castrated rat kidney, a mixture of b-estradiol and progesterone decreased SAT II activity from 208 ą48 to 87 ą 33 pmol/h x mg protein.

ß-estradiol; progesterone; sialyltransferase I; sialyltransferase II; testosterone

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