Francina Gonzalez De Los Santos, Ahmad El -Yaman El-Dandachli and Colleen Buggs-Saxton
Glucose provides fuel for cell metabolism and plays an important role in normal reproductive function. Glucose transporters such as (SLC2A1) facilitate entry of glucose into cells. We have previously shown that gonadotropin releasing hormone (GnRH) stimulates Slc2a1 expression in Lï¢T2 gonadotrope cells and in the pituitary gland of pre-pubertal mice. In this study we examined changes in Slc2a1 expression in the pituitary gland of mice after puberty and in Lï¢T2 gonadotrope cells treated with sex steroids. There were no detectable changes in Slc2a1 gene expression in the pituitary gland of pre-pubertal and adult male and female mice using real-time PCR analysis. In contrast, Western blot analysis detected higher levels of SLC2A1 protein in the pituitary gland of adult male and female mice compared to pre-pubertal male and female mice, respectively. In addition, peak levels of SLC2A1 protein as determined by Western blot analysis were detected in the pituitary gland of female mice during the proestrus and oestrus stages of the oestrous cycle. The proestrus stage corresponds to the surge of luteinizing hormone in the gonadotrope, which then triggers ovulation. Additional studies using immunofluorescent analysis of pituitary glands revealed increased co-localization of SLC2A1 with luteinizing hormone ï¢(LHï¢)ï in the gonadotrope cell of adult male and female mice compared to pre-pubertal mice. In vitro studies in Lï¢T2 cells did not detect any effects of estradiol and/or progesterone on Slc2a1 expression by real-time PCR analysis, but estradiol alone increased SLC2A1 protein levels in Lï¢T2 cells as determined by Western blot analysis. Furthermore, combined treatment of estradiol and progesterone induced glucose uptake in Lï¢T2 cells. Together, our findings show that regulation of Slc2a1 in the gonadotrope of adult mice likely reflects changes in sex steroids that are also important for pubertal development and fertility.