CNS stimulants Flashcards
(23 cards)
When GABA binds to GABAa receptors, it causes…
opening of chloride channels and the flow of chloride down its concentration gradient
Chloride is more concentrated inside or outside the cell? And when would be an exception to this?
Typically chloride ions are more concentrated outside the cell. In the primary afferent terminal of large diameter muscle fibres, chloride is more concentrated on the inside of the cell.
What is the result of primary afferent depolarization?
Presynaptic inhibition of neurotransmitter release on to the motoneuron
What are the actions of GABA post synaptically?
Hyperpolarization of motoneuron/postsynaptic membrane
GABA binding to GABAa receptor post-synaptically will result in which ion to move?
Opening of chloride channels resulting in influx of chloride ions
GABA binding to GABAb receptor post-synaptically will result in which ion to move?
Potassium efflux (out of the cell)
What happens when GABA binds to b receptors presynaptically?
Potassium efflux = Primary afferent hyperpolarization - the effect is great and terminates any action potential coming down
GABA also reduces pain by inhibiting ____ and ____ in the spinal cord.
Substance P and Glutamate
Baclofen MOA
- GABAb agonist
- Acts presynaptically by hyperpolarizing the cell and reducing neurotransmitter release
- Acts postsynaptically by hyperpolarizing motoneurons
- Motor outflow is reduced = less tension, less pain
Benzodiazepine MOA
- Acts on receptor GABAa but does not activate it
- Enhance presynaptic inhibition by increasing the frequency of chloride channel opening
- enhances the effects of GABA pre and post synpatically
Side effects of Benzodiazepines
Sedation, slurred speech, hypotension, bradycardia, apnea, confusion
Which is more effective, baclofen or benzodiazepine?
Equally effective but baclofen has shorter DOA (3-4hours)
Which is more sedating, baclofen or benzodiazepine?
Benzodiazepine
Disc herniation is the result of what protruding from the intervertebral disc and pinching the nerve?
Nucleus pulposus
Cyclobenzaprine MOA
- Decreases locus coeruleus neuron activity which normally facilitates lumbar motoneuron activity
- Dampens down facilitatory action from the brain to the motoneurons
Locus Coeruleus releases which neurotransmitter?
Norepinephrine so it is considered cholinergic
What does Locus Coeruleus do?
It’s axons project lumbar motoneurons and releases norepinephrine which either maintains or increases muscle tone
Noradrenaline is excitatory or inhibitory to motoneurons??
Excitatory
Why might someone say inhibiting Locus Coeruleus can potentially increase pain?
LC also projects into the dorsal horn and inhibits pain transmission. However its excitatory effects on motoneurons in the ventral horn are more powerful.
What are the drugs used to treat LBP?
NSAID, ASA, Acetaminophen, Codeine, Morphine and muscle relaxants
Cyclobenzaprine is structurally similar to which class of drugs?
Tricyclic antidepressants
Cylobenzaprine has antimuscarinic side effects which are…
Sedation, Dry mouth, Confusion, Dizziness
What is cyclobenzaprine’s onset of action and half life?
Onset at 1 hour and half life = 18h
