neuroactive ligands Flashcards
neuroactive ligands increase the diversity of coding by:
6 things
- existing in different locations throughout the nervous system
- having different effects at different receptor subtypes
- having fast or slow effects
- modulating the actions of other neurotransmitters
- traveling different distances to have their effects
- being released in singles, pairs (triplicates,…etc)
describe neurotransmitters (3)
- released at the synapse by pre-synaptic neurons
- act on specific proximal post-synaptic receptors
- alter membrane polarization
Neurohormones are released ______________________ by ____________________ and travel to relatively distal _________________
into the bloodstream
presynaptic neurons
neuronal targets
describe neuromodulators
- diffuse through large areas of the nervous system and effect multiple neurons
- not resorbed or deactivated
- spend more time in CSF (modulate overall activity level of neurotransmitters)
- in some ways parallel the activity of neurohormones
- receptors are typically coupled to G-proteins
what are the two receptor types?
Ionotropic and Metabotropic
describe ionotropic receptors (5)
-Fast acting
-linked directly to (opening) ion channels (causing EPSP or IPSP)
-effects last at most tens of milliseconds
-typically neurotransmitters act on these
-voltage- or Ligand-gated
(Voltage Gated: activated by changed in membrane potential near the channel
Ligand Gated: only open to specific bound ligands/drugs which binds to the receptor protein)
describe metabotropic receptors (5)
- Slower
- actions are mediated by metabolic functions
- activate G-proteins
- effects last hundreds of milliseconds to tens of seconds even hours
- typically neuromodulators act on these
What are the effects of psychotropic drugs on neurons?
9
- ) alters the integrity of the membrane
- ) alter the ion channels
- ) alter rate of neurotransmitter metabolism
- ) alter rate of neurotransmitter release
- ) alter the storage of neurotransmitters
- ) interfere with neurotransmitter inactivation
- ) mimic the action of a neurotransmitter
- ) block the action of a neurotransmitter
- ) toxicity
what are the 5 steps to neurotransmitter signaling?
- ) synthesis
- ) storage
- ) release
- ) postsynaptic action
- ) inactivation
what are the 8 criteria of a neurotransmitter?
- ) Must be found in pre-synaptic neurons
- ) enzymes required for synthesis must be found in pre-synaptic neurons
- ) A mechanism for terminating its activity must be present
- ) Stimulation of a presynaptic neuron and application of the ligand to the postsynaptic neuron should yield identical effects
- ) Following the stimulation of the presynaptic neuron, the ligand should be present in the cleft
- ) drugs that interfere with the post-synaptic reaction should block the effects of pre-synaptic neuronal stimulation
- ) drugs that interfere with pre-synaptic synthesis of the ligand should block the effects of the pre-synaptic neuronal stimulation
- ) drugs that block the inactivation enzyme should prolong the neurotransmitter’s actions
To understand how drugs can have behavioral effects, we have to consider what 2 things?
- where the neurotransmitter is in the nervous system
- what functions that neural system or circuit performs (and how the drug changes that function)
What are two classical neuroactive ligands?
amines and amino acids
more information on slide
What are three behaviors/physiological processes acetylcholine is responsible for?
memory
depression
initiation and maintenance of REM sleep
(more information on ACh on slide)
Where are the main sources of ACh in the CNS?
Basal Forebrain and Pedunculopontine tegmental nucleus
Where is ACh released?
at the neuromuscular junction in the PNS
