Interleukin 1α stimulates lactate dehydrogenase a expression and lactate production in cultured porcine Sertoli cells

By using cultured porcine Sertoli cells as a model, the action of interleukin 1 alpha (IL-1 alpha) on lactate production and the site of this action were studied. IL-1 alpha stimulated Sertoli cell lactate production in a time- and dose-dependent manner (with a half-maximal effect [ED50] of 6 pM). Two major sites involved in IL-1 alpha action were identified. First, IL-1 alpha was shown to increase the uptake of glucose substrate in a time- and dose-dependent manner. The maximal effect, with an ED50 of 10 pM, was observed after 24 h of treatment. Second, IL-1 alpha increased the activity of the lactate dehydrogenase (LDH) A4 isoform, which is involved in the conversion of pyruvate into lactate. This increase in LDH A4 activity was detected at 12 h and was maximal, with an ED50 of 9 pM, after 24-h treatment with IL-1 alpha. The increase was related to an increase in LDH A4 expression, since IL-1 alpha stimulated LDH A mRNA (size: 1.5 kilobases, evidenced through Northern blotting analysis) in a dose- and time-dependent manner. Assuming that IL-1 alpha might be produced in the seminiferous tubules by both Sertoli and germ cells, which utilize lactate for their energy metabolism, we suggest that these results together show 1) that the cytokine may represent a signal in the metabolic cooperation existing between Sertoli cells and germ cells, and 2) that a redistribution of LDH isoforms in favor of LDH A4 under IL-1 alpha control is a key mechanism(s) in such cooperation used by germ cells to enhance lactate production in Sertoli cells.