Autonomic Neuroscience: Basic and Clinical (2013)
Two of the major autonomic cell groups in the ventral
medulla are the bulbospinal catecholamine- and serotonin-containing neurons.
The number and distribution of glutamate receptors located on these two types
of neurons is likely to shape their function and how they contribute to various
physiological and pathophysiological processes. NMDA receptors are a type of
glutamate receptor that are made up of a five subunits (pentameric), one of which, that will
serve as a marker for NMDA receptors in this study, is the NR1 subunit. The
purpose of this study was to determine the number of bulbospinal catecholamine-
and serotonin-containing neurons that contained the NR1 subunit, and thus NMDA
receptors.
To test this hypothesis, a
group of 10 rats were housed in the lab with unlimited food and water. The rat spinal cords were
injected with a retrograde tracer called cholera toxin B (CTB) before perfusion
and subsequent sacrifice. The rat brains were sectioned and triple
immunofluorescently labeled for NR1 (NMDA marker), CTB (bulbospinal indicator),
and either TH or TpTH (catecholamine and serotonin enzyme, respectively) on 12
sections in the RVLM. The reason this study focused on TH and TpTH neurons is
because they are known to be important for sympathetic control of the
cardiovascular system. The stained
sections were examined under a microscope and the NR1-positive neurons were
counted.
The results showed that virtually all bulbospinal TH and non-TH
neurons in the RVLM, and all bulbospinal TpTH and non-TpTH in raphe pallidus
and parapyramidal region, express NR1. However, even though the NR1 subunit is
considered obligatory for functional NMDA channels, it is possible that some of
the neurons express the NR1 subunit but do not have functional NMDA channels. It
is thought that NMDA-mediated neurotransmission in the RVLM may contribute to
neuroplasticity.
- Ben Huber
- Ben Huber
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