Journal of Dental Research, Vol 80, 1736-1741, Copyright © 2001 by International & American Associations for Dental Research Online Journals
Qualitative light and electron microscope study of glutamate receptors in the caudal spinal trigeminal nucleus of the rat
F. R. Tang, J. F. Yeo and S. K. Leong
Neuroscience Research Laboratory, National Neuroscience Institute, Singapore.
Though ionotropic and metabotropic glutamate receptors have recently been
recognized to play important roles in the transmission of orofacial
nociceptive impulses, their detailed distribution in the spinal trigeminal
nucleus has not been systematically investigated. There is also controversy
regarding the electron microscope localization of metabotropic receptors.
We therefore undertook this investigation to address the above-mentioned
issues in the caudal part of the spinal trigeminal nucleus, using light and
electron microscope immunocytochemistry, to provide baseline information
for the development of agonists and antagonists of these receptors in the
clinical treatment of orofacial pain. The results showed some moderately to
strongly stained glutamate receptor 1 neurons, and many strongly stained
glutamate receptor 2/3 neurons in lamina II of the nucleus, suggesting that
the latter may play an important role in orofacial pain processing, with
the former playing a minor role. The metabotropic glutamate receptor 1
immunoreactive product was localized mostly in dendrites, while most of the
metabotropic glutamate receptors 2/3 immunoreactive product was deposited
in axon terminals containing synaptic vesicles of different shapes,
suggesting that glutamate receptors 2/3 may control the release of both
excitatory and inhibitory neurotransmitters.
