Effect of epidermal growth factor/transforming growth factor alpha on lactate production in porcine Sertoli cells: glucose transport and lactate dehydrogenase isozymes as potential sites of action.

Germ cell development is dependent upon the delivery of essential nutriments such as lactate originating from Sertoli cells. Lactate production is under the systemic control but probably also under a local control exerted via certain growth factors. By using a model of porcine cultured Sertoli cells, we have characterized the action of epidermal growth factor (EGF) on lactate production and further delineated the potential biochemical mechanisms involved in the EGF action. EGF stimulated lactate production in a time and dose dependent manner with a half-maximal (ED50) and maximal effects, respectively with 3.8 (0.6 x 10(-9) M) and 22 ng/ml of EGF. Lactate formation involves several biochemical steps among which the glucose substrate uptake and transport system as well as the lactate dehydrogenase (LDH) activity appear to play key roles. We report here that EGF increased the uptake of glucose evaluated through that of 2-deoxy-D-glucose (2-DOG), a non-metabolizable glucose analog. Such an increase in glucose substrate uptake occurs both after a long term (48 h) and a short term treatment (ED50 = 6.4 ng/ml, 1.1 x 10(-9) M EGF). Moreover, EGF was also able to enhance the activity of the Sertoli cell LDH. The maximal effect of the growth factor on LDH activity was observed after a long term (24 h) treatment with an ED50 of 7 ng/ml (1.2 x 10(-9) M).(ABSTRACT TRUNCATED AT 250 WORDS)