Final Flashcards
How is acetylcholine terminated at cholinergic synapses?
- Acetylcholinesterase will degrade ACh into the parts that are needed to synthesize more ACh
- these parts are transported into the presyn cell
How is choline transported across the presyn membrane?
- cotransport with sodium
- secondary active transport
How is GABA and glutamate signaling terminated?
- via reuptake back into the presyn cell, does not get broken down
How are GABA and glutamate transported across the presyn membrane?
- via cotransport with sodium, using the sodium gradient
- secondary active transport
How are GABA and glutamate transported across vesicular membranes?
- cotransport antitransport - goes in the opp direction that the ion is being moved normally
- uses the acidic hydrogen gradient
What are the two major catabolic enzymes mediating catecholamine degradation?
- COMT (catechol-O-methyltransferase) - methylates norepi or epi into another form
- MAO (monoamina oxidase) - oxidizes and brakes down molecules
What 2 catabolic enzymes mediate serotonin degradation?
- MAO - breaks it down into 5-HIAL
What are endocanniabinoids?
- endogenous chemical that activated cannabinoid receptors
- most widespread NT signaling system in the brain
- regulates memory and learning, immune function, pain perception
What are the two known endocanniabinoids?
- Anandamine
- 2-AG
Which cannabinoid receptor is found in the CNS? What type of receptor is it?
- CB1
- metabotropic - G-coupled receptor
- found in CNS
Which cannabinoid receptor is found in the peripheral tissue? What type of receptor is it?
- CB2
- metabotropic - g-coupled receptor
- found in peripheral tissue, mainly immune tissue
What other ligand is known to activated cannabinoid receptors?
- THC
How is endocanniabinoi signaling diff from most other types of synaptic signaling?
- retrograde signaling
- endocanniabinoid is produced by the postsyn cell, and the receptors for it are on the presyn cell
Where stimulates the release of endocanniabinoids?
- the enzyme that produces the endocanniabinoid is sensitive to calcium
- synthesizes on command/demand, are not stored in vesicles bc they are lipophilic
What is the effect of activating endocanniabinoid receptors?
- signal transduction pathway is activated, phosphorylating calcium channels, making them less leaky
- decreases calcium influx in presyn cell and postsyn cell, decreasing the amount of endocanniabinoid produced
What appears to be the overall function of endocanniabinoid signaling?
- appears to have a function in basic negative feedback
- prevents excessive synaptic activity by decreasing calcium influx and amount of endocanniabinoid produced
What are the two major types of glutamate receptors of the CNS?
- NMDA - chemically and voltage gated
- AMPA - only chemically gated
What types of receptors of the NMDA and AMPA receptors?
- ionotropic receptors
What is unique about the NMDA receptor?
- has both chemical and voltage gates
I-V curve for NMDA, what does this show? How is is diff. than others?
- when membrane potential is negative, there i not only an inward current, but it is not linear like other I-V curves
- inward current is maximized when the membrane is at around -30 mV
- shows that the channel has two gating mechanisms
What extracellular ion affects conductance of the NMDA receptor?
- magnesium
What is the overall effect of signaling cascades?
Activate signal transduction pathway/cascade
Excitatory or inhibitory by generating either EPSPs or IPSPs
Most common EX is the cAMP pathway
Eric Kandel
- used sea snails to study mechanisms of learning and association
- used gill withdrawal reflex
- sprayed the siphon (area covering gills) with water to reveal gill, and found that he could sensitize the snail’s response by pairing the spray with an electric shock
- made the snail withdraw its gills much faster, and over time, it became conditioned to withdraw its gill just as fast with just the water jet
Donald Hebb
- canadian psychologist that created the theory on which mechanisms need to occur in order for learning to occur
What is Hebb’s postulate? What is the concept of coincidence detection?
- cells that fire together wire together
- detecting two different types of stimuli in order to associate one thing with another
What are LTP and LTD, and how do they relate to Hebbian theory?
- LTP (long term potentiation) - strengthening of a synapse
- LTD (long term depression) - weakening of a synapse
How does the NMDA receptor function as a coincidence detector?
Has both chemical and voltage gates
What cellular and molecular mechanisms/processes did we discuss that underlie LTP and LTD?
- hippocampus is involved
- LTP - there is a stronger postsyn response than presyn response
- LTD - there is a weaker postsyn response than presyn response
Processes involved in early LTP
- occurs when more AMPA receptors are made available on the postsyn cell via exocytosis
- triggered by additiono f phosphate by CaMKII
Processes involved in early LTD
- occurs when there are less AMPA receptors made available on the postsyn cell via endocytosis
- AMPA receptors are taken away from the synapse
- triggered by phosphorylation by PP2B or PP1
Processes involved in late LTP
- synapse is being remodeled, which requires more protein synthesis
- calcium binds to calmodulin in the cell, which activated either CamKII or CamKIV
- CamKIV activates CREB, and transcription factor that binds to a regulatory sequence that regulates production of a gene
Processes involved in late LTD
- synapse is being shrunk, which might also require more protein synthesis
