The midcycle increase in ovarian glucose uptake is associated with enhanced expression of glucose transporter 3: Possible role for interleukin- 1, a putative intermediary in the ovulatory process

This study characterizes the rat ovary as a site of hormonally dependent glucose transporter (Glut) expression, and explores the potential role of interleukin (IL)-1, a putative intermediary in the ovulatory process, in this regard. Molecular probing throughout a simulated estrous cycle revealed a significant surge in ovarian Glut3 (but not Glut1) expression at the time of ovulation. Treatment of cultured whole ovarian dispersates from immature rats with IL-1β resulted in upregulation of the relative abundance of the Glut1 (4.5-fold) and Glut3 (3.5-fold) proteins as determined by Western blot analysis. Other members of the Glut family (i.e., Gluts 2, 4, and 5) remained undetectable. The ability of IL-1 to upregulate Glut1 and Glut3 transcripts proved time-, dose-, nitric oxide-, and protein biosynthesis-dependent but glucose independent. Other ovarian agonists (i.e., TNFα, IGF-1, interferon- γ, and insulin) were without effect. Taken together, our findings establish the mammalian ovary as a site of cyclically determined Glut1 and Glut3 expression, and disclose the ability of IL1 to induce the ovarian expression as well as translation of Glut1 and Glut3 (but not of Gluts 2, 4, or 5). Our observations also establish IL-1 as the first known regulator of Glut3, the most efficient Glut known to date. In so doing, IL-1, a putative component of the ovulatory process, may be acting to meet the increased metabolic demands imposed on the growing follicle and the ovulated cumulus-enclosed oocyte.