Particular subpopulations of midbrain and hypothalamic dopamine neurons express vesicular glutamate transporter 2 in the rat brain

M Kawano, A Kawasaki, H Sakata‐Haga… - Journal of …, 2006 - Wiley Online Library
M Kawano, A Kawasaki, H Sakata‐Haga, Y Fukui, H Kawano, H Nogami, S Hisano
Journal of Comparative Neurology, 2006Wiley Online Library
Abstract Vesicular glutamate transporters (VGLUT1,‐2, and‐3) mediate the accumulation of
transmitter glutamate into synaptic vesicles in glutamatergic neurons. VGLUT1 and VGLUT2
are more reliable glutamatergic neuron markers, since VGLUT3 also exists in other neuron
types. To study whether the dopaminergic neuron uses glutamate as a cotransmitter, we
analyzed VGLUTs expression in dopamine neurons of adult male rats by in situ
hybridization and immunohistochemistry. In the ventral midbrain, in situ hybridization …
Abstract
Vesicular glutamate transporters (VGLUT1, ‐2, and ‐3) mediate the accumulation of transmitter glutamate into synaptic vesicles in glutamatergic neurons. VGLUT1 and VGLUT2 are more reliable glutamatergic neuron markers, since VGLUT3 also exists in other neuron types. To study whether the dopaminergic neuron uses glutamate as a cotransmitter, we analyzed VGLUTs expression in dopamine neurons of adult male rats by in situ hybridization and immunohistochemistry. In the ventral midbrain, in situ hybridization analysis revealed no VGLUT1 mRNA expression, a widespread but discrete pattern of VGLUT2 mRNA expression, and a highly limited expression of VGLUT3 mRNA. Reverse‐transcriptase polymerase chain reaction analysis detected full‐length VGLUT2 gene transcripts in the ventral midbrain. Using in situ hybridization combined with tyrosine hydroxylase (TH) immunostaining, only VGLUT2 signals were detectable in some TH‐labeled neurons of A10 dopamine neuron groups, with the highest incidence (20%) in the rostral linear nucleus of the ventral tegmental area. In the forebrain, VGLUT2 signals were demonstrated in half of the A11 TH‐labeled neurons in the hypothalamus. Double‐label immunostaining for VGLUT2 and vesicular monoamine transporter 2 or TH showed that double‐labeled varicosities are rarely observed in any target regions examined of A10 and A11 dopamine neuron groups. These results indicate that VGLUT2 is expressed in subsets of A10 and A11 dopamine neurons, which might release dopamine and glutamate separately from different varicosities in the majority of their single axons. J. Comp. Neurol. 498:581–592, 2006. © 2006 Wiley‐Liss, Inc.
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