Neurotransmitters Flashcards
Main amino acid neurotransmitters
glutamate
GABA
glycine
glutamate
main excitatory transmitter in CNS
GABA
main inhibitory transmitter. Synthesized from glutamate and causes Cl- influx
glycine
inhibitory transmitter in the brain stem, spinal cord and retinal tissue
Main Monoamines
Da
NE
5Ht
the NT involved in learning, and may cause parkinsonian like symptoms if depleted
DA
NT invovled in arousal, fight or flight
NE
the NT involved in mood control, and released by the raphé nuclei
5HT
the NT involved with CNS modulation and muscle contraction
Acetyl choline
Nitric Oxide
promotes vasodilation and CNS modulation
the main NT in taste cells, and co transmitter in many diverse synapses
ATPs
a ____ is a small 10 AA length chain that modifies the effects of other neurotransmittesr on the target receptor
Neuropeptides.
Dales Principle
individual neurons may release more than one transmitter but they typically release the same combination of substances into the synpase
5 main types of neuropeptides
1) ADH/Vasopressin
2) Oxytocin
3) Substance P
4) Dynorphin
5) Neuropeptide Y
ADH
Controls fluid balance and reproductive behavior
Oxytocin
induces labor, controls reproductive behavior
neuropeptide that modulates pain
dynorphin
substance P
modulates pain SENSITIVITY
Neuropeptide Y
regulates appetite.
mechanism and effecs of MDMA. Side effectS?
causes serotonin to stay in the synapse longer. More intense mood effects; increase pleasure, feelings of closeness. Causes depression afterwards due to serotonin depletion. research shows it irreversibly damages serotonergic axons; may cause chronic depression and impulsivity and impaired verbal memory in chronic users.
Neuromodulation
the alteration of a neurons response to a specific synapse or neurotransmitter. substances can act as neuromodulators.
Ionotropic receptors
ligan gated ion channels that open up when activated by the binding of a neurotransmitter. Ions then flow through the central pore.
example of an ionotropic receptor
AMPA: opens in response to glutmate and allows Na+ to flow into cell (excitatory)
Metabotropic receptors. Which receptor causes change the fastest? Metabotropic or ionotropic?
no cental power, but they are COUPLED to nearby ion channesl and can employ SECOND MESSENGER SYSTEMS as an intermediary step. They are slower to take effect but they are longer lasting
4 main glutamate receptors
AMPA and NMDA and kainate (open in response to kainic acid) and metabotropic glutamate receptor: category of metabotropic receptors that act as AUTORECEPTORs.
why is NMDA receptor so special
because it is both ligand gated and voltage gated.
It requires glutamate for activation (ligand gated) in addition to indirect ligands such as glycine, polyamines and Zn2+, and the channel is alos blocked by magnesium at negative membrane potentials. therefore, NMDA central pore only lets positive ions through when glutamate is bound to the receptor and when the membrane is POSITIVELY (potentiated)?
which ions flow through NMDA? What happens to the inside of the celL?
primarily calcium. Ca2+ influx can activate second messenger systems that play a role in plasticity.
NMDA receptor contains _____ suunits that each contain a ___ ___ ___
4 subunits that each contain a glutamate binding site.
Extrasynaptic receptor
when receptors on post syn cell is very far away from the pre syn cell that releases the neurotransmitter.
pre syn neurons reach extrasynpatic receptors via : ___ ___
volume transmission: release of neurotransmitter into the EXTRACELLULAR SPACE rather than synapse in order to DIFFUSE to the far away receptor.
pro and con of volumetric transmission.
it can influence many neurons at once
con: cannot communicate detailed info like synaptic transmission.
a ____ is required for transmitter synthesis but it itself is not a neurotransmitter
precursor.
how is acetylcholine made? what enzyme catalyzes this reaction?
acetyl coA precursor reacts with choline to create acetylchloine and CoA. Reaction is catalyzed by Cholineacetyltransferase.
2 main cholinergic projections:
1) brainstem projection system: stems from the DORSOLATERAL PONTINE SYSTEM and projects into brain stem structures like the LOCUS COERULEUS, Retricular formation, rapheé nuclei, thalamus, cerebellar nuclei and tectum (mid brain component)
2) Forebrain system: the limbic branch and the cortical branch.
limbic branch: cholinergic neurons branch from the MEDIAL SEPTUM to reach HIPPOCAMPUS, amygdala, hypothalamus and olfaction regions.
cortical branch: cholinergic neruons branch the NUCLEUS BASALIS and projects into the neocortex.
acetyl choline esterase
separates Ach into choline and acetate. choline can get transported back into the presynaptic cell and be used for making more Ach later
How can you prevent choline from being transported back into the pre synaptic cell?
using the drug called Hemischolinium, which INACTIVATES the transporter.
2 main types of ACh receptors. What stimulates them and inactivates them?
1) nicotinic: found in PNS (neuromuscular junctions) . IONOTROPIC and stimulated b nicotine and blocked by curare.
2) muscarinic: METABOTROPIC RECEPTORS stimulated by muscarine and blocked by atrophine.
HOw does the botulism toxin work?
ACh antagonist. causes paralysis by PREVENTING Ach release at terminal buttons. (often in PNS)
how does black widow venom work?
ACh AGONIST. Causes contraction of muscle by facilitating the Ach Release
What is Hemmicholinium
a drug that stops the choline transporters and prevents Ach recycling/synthesis
what is neostigmine
inhibitor of acetylcholinesterase. Prevents Ach breakdown
what is atropine
blocks the muscarinic receptors. Therefore causes paralysis in CNS
What is curare
blocks nicotinic receptors. Therefore causes paralysis in PNS