Week 7 Flashcards
Glutamate receptor types
- Ionotropic
- Metabotropic
Ionotropic Glutamate Receptors
- AMPA (univalent cations: Na)
- NMDA (uni/divalent cations: Na/Ca)
What receptor has a plug
NMDA glutamate-R
Mg2+ Extracellular plug
(inh. by PCP)
Metabotropic Glutamate Receptors
- 1/5: Gq
- 2/3/4/6/7/8: Gi
(total 8)
Ionotropic receptor structure
- 4 subunits (heterotetramer)
- Each subunit has 3 TM domains
- 10+ types
- Fast / rapid signalling
Metabotropic receptor structure
- G-protein coupled
- 8 types
What typically causes EPSP
Ligand gated Non-selective cation channel opening
What typically causes IPSP
Ligand gated chloride channels (or K+)
GABA receptor types
- GABA(A)
- GABA(B)
GABA (A) -R
- Ligand gated Cl- channel
- Tranquilizers activate these
GABA (B) -R
- G-coupled 7TM receptor
- Gi
- K+ channel opens (BY subunit)
GABA (A) -R Structure
- Pentameric (5 subunits)
- Each subunit has 4TM domains
- Analogs: nACh-R, Gly-R, 5-HT3
Temporal summation
1 presynaptic neuron releases NT many times over a short period and PSPs are added together
Spatial summation
Sum. of PSPs from multiple neurons at the same time which is more powerful than temporal summation
Non-adapting pattern
- Quick depol/repol
- VG Na & K+ channels
- High AP frequency
Adapting pattern
- Slowly-activating K+ channels (+VG Na/K)
- Increased hyperpol. so AP frequency decreases
Rhythmic bursting pattern
- VG Ca+ channels & Ca+ activated K+ channels
- Strong hyperpol. after Ca+ channel opening
Burst firing
- Small EPSP cannot reach threshold of VG Na+ channels
- T-type Ca channels open to help reach VG Na channel threshold leading to Burst
Types of increased Synaptic Plasticity
- Facilitation: <1s
- Augmentation: seconds
- Potentiation: 10s of s to minutes
- LT-potentiation: hours, days
Types of decreased Synaptic Plasticity
- Habituation: inactivity
- Depression: high or persistent low AP freq.
- LT-depression
AMPA phosphorylation
Increases synaptic strength
Where does LTP happen
Hippocampus
What maintains Astrocyte shape
Specific intermediate filament & Glial fibrillar acidic protein (GFAP)
Bergmann glial cells
Special astrocytes with parallel processes to purkinje cells
2 Types of Astrocytes
- Fibrous (white m)
- Protoplasmic (grey m)
Neurons energy sources
- Glucose through GLUT3
- Lactate from Astrocytes (GLUT1)
What is used to move lactate from astrocyte to neuron
MCT1 & MCT2
Astrocyte regulation of K+ levels (Channels)
- Na/K ATPase
- Na/K/2Cl cotransport
- K channels
Neuron resting Em (& increased K+)
-65 mV
(+5 mV)
Astrocyte resting Em (& increased K+)
-85 mV
(+25 mV)
Glutamate transporters on Neuron & Astrocytes
- Neuron (EAAT 3)
- Astrocyte (EAAT 1/2)
Glutamine transporters brain
SNAT
Microglial cells
- Macrophages of CNS
- 20% of glial
- Most effective APC in brain
