title: GnRH increases glucose transporter-1 expression and stimulates glucose uptake in the gonadotroph.
abstract: GnRH is the main regulator of the hypothalamic-pituitary-gonadal (H-P-G) axis. GnRH stimulates the pituitary gonadotroph to synthesize and secrete gonadotrophins (LH and FSH), and this effect of GnRH is dependent on the availability of glucose and other nutrients. Little is known about whether GnRH regulates glucose metabolism in the gonadotroph. This study examined the regulation of glucose transporters (Gluts) by GnRH in the LβT2 gonadotroph cell line. Using real-time PCR analysis, the expression of Glut1, -2, -4, and -8 was detected, but Glut1 mRNA expression level was more abundant than the mRNA expression levels of Glut2, -4, and -8. After the treatment of LβT2 cells with GnRH, Glut1 mRNA expression was markedly induced, but there was no GnRH-induction of Glut2, -4, or -8 mRNA expression in LβT2 cells. The effect of GnRH on Glut1 mRNA expression is partly mediated by ERK activation. GnRH increased GLUT1 protein and stimulated GLUT1 translocation to the cell surface of LβT2 cells. Glucose uptake assays were performed in LβT2 cells and showed that GnRH stimulates glucose uptake in the gonadotroph. Finally, exogenous treatment of mice with GnRH increased the expression of Glut1 but not the expression of Glut2, -4, or -8 in the pituitary. Therefore, regulation of glucose metabolism by GnRH via changes in Gluts expression and subcellular location in the pituitary gonadotroph reveals a novel response of the gonadotroph to GnRH.
authors: Division of Endocrinology, Department of Pediatrics, Children's Hospital of Michigan, Wayne State University School of Medicine, 3901 Beaubien Boulevard, 421 E. Canfield, Detroit, Michigan 48201-2119, USA.
authors: Valerie M
authors: VM
authors: Harris
authors: Sachin V
authors: SV
authors: Bendre
authors: Francina
authors: F
authors: Gonzalez De Los Santos
authors: Alemu
authors: A
authors: Fite
authors: Ahmad
authors: A
authors: El-Yaman El-Dandachli
authors: Lyazat
authors: L
authors: Kurenbekova
authors: Abdul B
authors: AB
authors: Abou-Samra
authors: Colleen
authors: C
authors: Buggs-Saxton
mesh_terms: D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism*; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism*; D052681:Gonadotrophs / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation / Q000187:drug effects; D010902:Pituitary Gland / Q000254:growth & development / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D051246:Glucose Transport Proteins, Facilitative; D051272:Glucose Transporter Type 1; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; C495678:Slc2a1 protein, mouse; D007987:Gonadotropin-Releasing Hormone; D048049:Extracellular Signal-Regulated MAP Kinases; D005947:Glucose