Localization of glucokinase-like immunoreactivity in the rat lower brain stem: for possible location of brain glucose-sensing mechanisms.
Pancreatic glucokinase (GK) is considered an important element of the glucose-sensing unit in pancreatic beta-cells. It is possible that the brain uses similar glucose-sensing units, and we employed GK immunohistochemistry and confocal microscopy to examine the anatomical distribution of GK-like immunoreactivities in the rat brain. We found strong GK-like immunoreactivities in the ependymocytes, endothelial cells, and many serotonergic neurons. In the ependymocytes, the GK-like immunoreactivity was located in the cytoplasmic area, but not in the nucleus. The GK-positive ependymocytes were found to have glucose transporter-2 (GLUT2)-like immunoreactivities on the cilia. In addition, the ependymocytes had GLUT1-like immunoreactivity on the cilia and GLUT4-like immunoreactivity densely in the cytoplasmic area and slightly in the plasma membrane. In serotonergic neurons, GK-like immunoreactivity was found in the cytoplasm and their processes. The present results raise the possibility that these GK-like immunopositive cells comprise a part of a vast glucose-sensing mechanism in the brain.
Maekawa
F
F
Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Toyoda
Y
Y
Torii
N
N
Miwa
I
I
Thompson
R C
RC
Foster
D L
DL
Tsukahara
S
S
Tsukamura
H
H
Maeda
K
K
D000818:Animals; D000918:Antibody Specificity; D001933:Brain Stem / Q000201:enzymology*; D004805:Ependyma / Q000166:cytology / Q000378:metabolism; D005260:Female; D005941:Glucokinase / Q000276:immunology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007150:Immunohistochemistry; D020547:Lateral Ventricles / Q000378:metabolism; D018613:Microscopy, Confocal; D011903:Raphe Nuclei / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism; D017552:Solitary Nucleus / Q000201:enzymology; D013347:Subcellular Fractions / Q000201:enzymology; D016707:Tissue Fixation
D012701:Serotonin; D005941:Glucokinase; D005947:Glucose