title: Immunohistochemical localization of GLUT3, MCT1, and MCT2 in the testes of mice and rats: the use of different energy sources in spermatogenesis.
abstract: Lactate represents a preferential energy substrate of germ cells rather than glucose. Testicular Sertoli cells are believed to produce lactate and pyruvate and to supply these to germ cells, particularly spermatocytes and spermatids. Monocarboxylate transporter (MCT), responsible for the transport of lactate and other monocarboxylates via the cell membrane, is abundant in the testes and sperm (MCT1, MCT2, and MCT4). For the uptake of glucose, germ cells within the seminiferous tubules and sperm have been known to intensely express GLUT3. The present study investigated expression profiles of MCTs and GLUTs and revealed their cellular and subcellular localization in the mouse and rat testis. An in situ hybridization analysis showed significant expressions of MCT1, MCT2, and GLUT3 mRNA in the testis. Immunohistochemically, spermatogonia, spermatocytes, and spermatids expressed MCT1 on their cell surfaces in a stage-dependent manner: in some seminiferous tubules, an intense expression of MCT1 was unique to the spermatogonia. MCT2 was restricted to the tails of elongated spermatids and sperm. An intense immunoreactivity for GLUT3 was shared by spermatocytes, spermatids, and sperm. Sertoli cells were devoid of any immunoreactivities for MCT1, MCT2, and GLUT3. The predominant energy source of germ cells may be lactate and other monocarboxylates--especially for spermatogonia, but glucose and other hexoses may be responsible for an energy supply to spermatocytes and spermatids.
authors: Department of Anatomy, Graduate School of Medicine, Hokkaido University.
authors: Ayuko
authors: A
authors: Kishimoto
authors: Toshina
authors: T
authors: Ishiguro-Oonuma
authors: Ritei
authors: R
authors: Takahashi
authors: Mamiko
authors: M
authors: Maekawa
authors: Kiyotaka
authors: K
authors: Toshimori
authors: Masahiko
authors: M
authors: Watanabe
authors: Toshihiko
authors: T
authors: Iwanaga
mesh_terms: D000818:Animals; D005260:Female; D015870:Gene Expression; D051274:Glucose Transporter Type 3 / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D027501:Monocarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D013091:Spermatogenesis; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D051274:Glucose Transporter Type 3; D027501:Monocarboxylic Acid Transporters; D012333:RNA, Messenger; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C490426:Slc16a7 protein, mouse; C091633:Slc16a7 protein, rat