Cross references: Amphioxus Neurotransmitters Glutamate
Glutamate Gate Glutamate Metabotropic Receptor Subcortical Brain Searching for "amphioxus glutamate" yielded: PubMed = 8 http://www.ncbi.nlm.nih.gov/pubmed/?term=amphioxus+glutamate Google = 175,000 https://www.google.com/search?q=amphioxus+glutamate&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=np&source=hp PubMed 1: A neurochemical map of the developing amphioxus nervous system PubMed 3: The amphioxus (Branchiostoma floridae) genome contains a highly diversified set of G protein-coupled receptors. http://www.ncbi.nlm.nih.gov/pubmed/18199322 PubMed 4: N-methyl-D-aspartic acid (NMDA) in the nervous system of the amphioxus Branchiostoma lanceolatum. (Goog) http://www.ncbi.nlm.nih.gov/pubmed/18096065?dopt=AbstractPlus The link leads to an abstract, but the full article comes up when you click on either of two boxes in the upper right corner offering it for free. from the Abstract:
"NMDA (N-methyl-D-aspartic acid) is a widely known agonist for a class of glutamate receptors, the NMDA type. Synthetic NMDA elicits very strong activity for the induction of hypothalamic factors and hypophyseal hormones in mammals. Moreover, endogenous NMDA has been found in rat, where it has a role in the induction of GnRH (Gonadotropin Releasing Hormone) in the hypothalamus, and of LH (Luteinizing Hormone) and PRL (Prolactin) in the pituitary gland." "In this study we show evidence for the occurrence of endogenous NMDA in the amphioxus Branchiostoma lanceolatum." PubMed 5: Free amino acids in the nervous system of the amphioxus Branchiostoma lanceolatum. A comparative study. Google: The first page of Google hits, which only numbered 14,100 this time instead of the 175,000 claimed hits last time, provided only one hit not included in the PubMed hits, above, and it wasn't useful. Surprisingly, the second through fourth pages didn't have anything about glutamate as a neurotransmitter. Most of the references were about genes and evolution. 2006 Tuning and playing a motor rhythm: how metabotropic glutamate receptors orchestrate generation of motor patterns in the mammalian central nervous system (Goog) http://jp.physoc.org/content/572/2/323.full Full length HTML available online for free. See also: Glutamate Metabotropic Receptor . from the Abstract: "Repeated motor activities like locomotion, mastication and respiration
need rhythmic discharges of functionally connected
neurons termed central pattern generators (CPGs)
that cyclically activate motoneurons even in the absence of descending
commands
from higher centres. For motor pattern generation,
CPGs require integration of multiple processes including activation of
ion channels and transmitter receptors at strategic
locations within motor networks. One emerging mechanism is activation
of glutamate metabotropic receptors (mGluRs)
belonging to group I, while group II and III mGluRs appear to play an
inhibitory
function on sensory inputs. Group I mGluRs generate
neuronal membrane depolarization with input resistance increase and
rapid
fluctuations in intracellular Ca2+,
leading to enhanced excitability and rhythmicity. While synchronicity is
probably due to modulation of inhibitory synaptic
transmission, these oscillations occurring in
coincidence with strong afferent stimuli or application of excitatory
agents
can trigger locomotor-like patterns. Hence,
mGluR-sensitive spinal oscillators play a role in accessory networks for
locomotor
CPG activation. In brainstem networks supplying
tongue muscle motoneurons, group I receptors facilitate excitatory
synaptic
inputs and evoke synchronous oscillations which
stabilize motoneuron firing at regular, low frequency necessary for
rhythmic
tongue contractions. In this case, synchronicity
depends on the strong electrical coupling amongst motoneurons rather
than
inhibitory transmission, while cyclic activation of
KATP conductances sets its periodicity. Activation of mGluRs is therefore a powerful strategy to trigger and recruit patterned
discharges of motoneurons.
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