CNS Pharmacology Flashcards
Blood Brain Barrier
Isolates the CNS
Modified endothelial cells so there are tight junctions instead of fenestrations
Highly lipophilic
Astroglial processes and pericytes surround the endothelial cells
Up-regulation (sensitization)
You have a drug that is blocking the receptor or something, so the postsynaptic cell is making more receptors to try to get any of the NT. When you remove the drug you can have an amplified response because you have way more receptors now
Down-regulation (desensitization)
Also called tolerance
Drug stops working after a while because there is a max response of receptors for a long time so the postsynaptic receptors are internalized and degraded which means less of a response is generated
Membrane delimited metabotropic ion channel
Ligand binds to receptor (7 TM one), activates G protein, and then the G protein subunits go and directly activated an ion channel (usually K)
Diffusible second messenger metabotropic ion channel
GPCR activated by ligand, binds G protein, creates second messengers, then they can go activate and open ion channels
Steps of an action potential
- Excitatory impulse reaches the cell
- Na channels open and Na enters the cell (cell membrane depolarizes
- K channels open, K begins to leave the cell (slowing of depolarization)
- Na channels close when cell gets too positive
- K leaves cell (repolarization)
- K channels close (afterhyperpolarization)
- Excess K outside diffuses away
Cellular Organization
- Long tract
- Local circuit
- Divergent
- Messages over long distances, motor control
- Short, modulating, shape recognition in the optic tract
- Widely projecting neurons, global functioning, sleep-wake cycles
4 Criteria for a NT
- To be present at higher [ ] in the synapse than in other areas (localized)
- To be released by electrical or chemical stimulation via a Ca dependent mechanism
- Produce a postsynaptic response similar to nerve stimulation (synaptic mimicry)
- Mechanism for termination of transmitter action
Amino acid NTs
High concentration in the SNS
Potent modifiers of excitability
Excitatory: Glutamate
Inhibitory: GABA and glycine
GABA synthesis
Glutamine –(glutaminase)–> glutamate –(glutamate decarboxylase)–> GABA
Glutamate
where, types, termination
Major excitatory NT in CNS
Ionotropic subtypes: NMDA receptor, AMPA receptor and KA receptor
Also mGluR 1 (postsynaptic Gq) and 2/3 (presynaptic, Gi)
Termination: Glia Uptake
GABA
Function, receptors
Inhibitory
Ionotropic (GABAa, Cl-) and metabotropic (GABAb; Gq)
Widely expressed
GABAb can be presynaptic
Ligand gated ion channels (it is the orthosteric ligand, barbituates are the allosteric ligand)
Glycine
Function, receptors, location
Inhibitory
Ionotropic (Cl-)
Limited expression (interneurons in spinal chord and brainstem)
Acetylcholine
Receptors, function, disease target
Has ionotropic (nicotinic receptor) and metabotropic (muscarinic receptor)
Excitatory/Inhibitory
Widely expressed
Cognitive functions (sleep, wakefulness)
Target in treatment of Alzheimer’s disease
Ionotropic
Ion channels - not GPCRs