VGluT1- and GAD-immunoreactive terminals in synaptic contact with PAG-immunopositive neurons in principal sensory trigeminal nucleus of rat.
OBJECTIVE
To trace the origin of abundant vesicular glutamate transporter 1-like immunoreactive (VGluT1-LI) axon terminals in the dorsal division of the principal sensory trigeminal nucleus (Vpd) and the relationships between VGluT1-LI, as well as the glutamic acid decarboxylase (GAD)-LI axon terminals, and phosphate- activated glutaminase (PAG)-LI thalamic projecting neurons in the Vpd.


METHODS
Following unilateral trigeminal rhizotomy, triple-immunofluorescence histochemistry for VGluT1, GAD and PAG and the immunogold-silver method for VGluT1 or GAD, combined with the immunoperoxidase method for PAG were performed, respectively.


RESULTS
After unilateral trigeminal rhizotomy, the density of VGluT1-like immunoreactivity (IR) in the Vpd on the lesion side was reduced compared to its contralateral counterpart. Under the confocal laser-scanning microscope, the VGluT1-LI or GAD-LI axon terminals were observed to be in close apposition to the PAG-LI thalamic projecting neuronal profiles, and further electron microscope immunocytochemistry confirmed that VGluT1- and GAD-LI axon terminals made asymmetrical and symmetrical synapses upon the PAG-LI neuronal structures.


CONCLUSIONS
The present results suggest that the VGluT1-LI axon terminals, which mainly arise from the primary afferents of the trigeminal ganglion, along with the PAG-LI neuronal profiles, form the key synaptic connection involved in sensory signaling.
Dong
Yu-lin
YL
Department of Anatomy and K.K.Leung Brain Research Center, the Fourth Military Medical University, Xi-an 710032, China. jinlian@fmmu.edu.cn.
Zhang
Fu-xing
FX
Pang
You-wang
YW
Li
Jin-lian
JL
D000818:Animals; D005968:Glutamate Decarboxylase / Q000032:analysis*; D005972:Glutaminase / Q000032:analysis*; D008297:Male; D017729:Presynaptic Terminals / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology*; D014278:Trigeminal Nuclei / Q000737:chemistry / Q000166:cytology*; D050598:Vesicular Glutamate Transport Protein 1 / Q000032:analysis*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D050598:Vesicular Glutamate Transport Protein 1; D005680:gamma-Aminobutyric Acid; D005972:Glutaminase; D005968:Glutamate Decarboxylase