Glucose Transporter 1 (GLUT1) is Regulated in the Pituitary Gland during Puberty

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 134-163-GnRH & Gonadotroph Biology & Signaling
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-159
Francina Gonzalez De Los Santos*, Ahmad El-Yaman EL-Dandachli, Omar Basha and Colleen Buggs-Saxton
Wayne State University School of Medicine, Detroit, MI
Introduction:Glucose transporters facilitate entry of glucose into cells, and glucose is an important nutrient for normal reproductive function (1).  We have previously shown that gonadotropin releasing hormone (GnRH) markedly induces glucose transporter 1 (Glut1) expression in LβT2 gonadotrope cells and the pituitary gland of prepubertal mice (2).

Objective:In this study we investigated whether GLUT1 is regulated in the pituitary gland during pubertal development and the estrus cycle in C57BL/6J mice.   

Methods: Prepubertal (younger than 4 weeks of age) and pubertal (older than 2 months of age) male and female C57BL/6J mice were identified. Vaginal smears were performed in pubertal C57BL/6J female mice daily for 1-2 weeks to identify mice during different stages (diestrus, proestrus, and estrus) of the estrus cycle. RNA was isolated from the pituitary gland of male and female mice, and changes in the expression of Glut1 and LHβ genes were analyzed by real-time PCR. Whole cell extracts were isolated from the pituitary gland, cerebral cortex, and gonads for Western blot analysis with GLUT1 and α-tubulin antibodies. Immunofluorescence analysis with confocal microscopy was performed on paraffin-embedded sections of pituitary from prepubertal and pubertal male and female mice with GLUT1 and LHβ antibodies.

Results: There were no changes detected in Glut1 gene expression in the pituitary gland of prepubertal and  pubertal mice.  In contrast, GLUT1 protein levels increased 1.8-fold in the pituitary gland of male mice compared to prepubertal male mice (P < 0.05).  GLUT1 protein levels increased 2.5-fold during proestrus and 2.4-fold during estrus in pubertal compared to prepubertal female mice (P< 0.01).  Increased GLUT1 protein levels were also detected in the cerebral cortex and gonads of pubertal male mice compared to prepubertal male mice.  In contrast, no changes in GLUT1 protein levels were detected in the cerebral cortex or ovaries of prepubertal and pubertal female mice.  Immunofluorescence analysis of the pituitary gland showed that the pubertal increased levels of GLUT1 protein co-localized with LHβ in gonadotrope cells.

Conclusion: GLUT1 is regulated at the level of translation in the pituitary gland during puberty.  These findings suggest that translational control of GLUT1 in the pituitary gonadotrope may be important for normal pubertal development and reproductive function.

1. Energy balance and reproduction. Jill E Schneider Physiology & Behavior Volume 81, Issue 2, April 2004, Pages 289–317 2.GnRH increases glucose transporter-1 expression and stimulates glucose uptake in the gonadotroph.  Harris VM, Bendre SV, Gonzalez De Los Santos F, Fite A, El-Yaman El-Dandachli A, Kurenbekova L, Abou-Samra AB, Buggs-Saxton C. J Endocrinol. 2012 Feb;212(2):139-47. Epub 2011 Nov 22

Nothing to Disclose: FG, AEYE, OB, CB

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Wayne State University School of Medicine and Children's Hospital of Michigan