"Peter F." <effectivespamblock at ozemail.com.au>
> It is in *every way* plausible (i.e., not just because it has been
> evidenced) that some *key* type glutaminergic neurons ("key" in respect of
> what I am about to suggest - or perhaps rather assert and conclude), *can*
> to release substance-P at a 'certain' treshold of excitatory (at least
> potentially directly distress, or flight, motivating) firing, AND at some
> still higher frequency (or same frequency but longer duration?) some opioid
> type neuromodulator.
I'm not sure where your references are... but I just looked up some
evidence that pyramidal neurons may co-release peptides along with
glutamate. This may support the hypothesis that neuromodulation by
neuropeptides subserves an "information-overflow" mechanism. The
papers are kind of old, 1992-3.
Brain Res. 1993 Feb 5; 602(2): 336-41.
Chromogranin A, a soluble synaptic vesicle protein, is found in cortical
neurons other than previously defined peptidergic neurons in the human
Adams LA, Ang LC, Munoz DG.
Department of Pathology, University of Western Ontario, London, Canada.
Neuropeptides in the cerebral cortex have previously been identified in
non-pyramidal neurons only. By comparing the location of chromogranin A
(CgA), a soluble protein of large dense-core synaptic vesicles, with
that of SMI-32, neuropeptide Y (NPY), parvalbumin (PV) and calbindin
(CaBP) using double label immunohistochemistry, we demonstrate that CgA
is present in pyramidal neurons as well as in several subtypes of
PMID: 8448675 [PubMed - indexed for MEDLINE]
Brain Res. 1992 Dec 18; 599(1): 140-3.
Numerous SP-positive pyramidal neurons in cat neocortex are
Conti F, Fabri M, Minelli A.
Institute of Human Physiology, University of Ancona, Italy.
An immunocytochemical technique that allows visualization of two
antigens in the same neuron was used to verify the possibility that
some neocortical pyramidal neurons contain both glutamate (Glu) and
substance P (SP) immunoreactivity. The results show that a large
fraction of SP-positive pyramidal neurons are also Glu-positive,
and indicate that in a small population of cortical neurons a fast
excitatory synaptic transmitter and a slow peptidic modulator
PMID: 1283558 [PubMed - indexed for MEDLINE]