Autonomic Pharmacology 5 (Ocular)

Question 1

Which organ serves as an autonomic pharmacology laboratory? (i.e. easy to observe autonomic symptoms)

Answer 1

the eye

Question 2

Which receptor is found on the pupillary dilator? What does stimulation of this receptor cause?

Answer 2

alpha-adrenoreceptor –> mydriasis/pupil dilation

Question 3

Which receptor is found on the circular, pupillary constrictor? What does stimulation of this receptor cause?

Answer 3

muscarinic receptor –> miosis/pupil constriction

Question 4

What is another name for the pupillary dilator?

Answer 4

iris radial muscle

Question 5

What is another name for the circular, pupillary constrictor?

Answer 5

iris sphincter

Question 6

What receptor is found on the ciliary muscle? What does stimulation of this receptor cause?

Answer 6

muscarinic receptor; stimulation causes:
- contraction of the muscle

• myopia (for near vision)
• open trabecular meshwork –> aqueous humor outflow in canal of Schlemm to systemic circulation –> decrease IOP

Question 7

What receptor is found on the ciliary epithelium? What does stimulation of this receptor cause?

Answer 7

beta-adrenoreceptor –> increased secretion of aqueous humor from CILIARY BODY

Question 8

What are the 2 main classes of drugs used to treat glaucoma?

Answer 8

• M3 agonists
• beta-blockers

Question 9

What is the difference between open angle glaucoma and angle closure glaucoma? Which one is more commonly treated with drugs?

Answer 9

open angle glaucoma: high pressure between cornea and iris (treated with drugs)

angle closure glaucoma: high pressure between ciliary body and iris

Question 10

Name 6 drugs that can be used to treat glaucoma.

Answer 10

timolol
pilocarpine
physostigmine
adrenaline
apraclonidine
cannabinoids

Question 11

What is timolol commonly used to treat? What class of drugs does it belong to? What is its mechanism for treatment?

Answer 11

treats: glaucoma
class: beta-blocker
mechanism: reduces secretion of aqueous humor from ciliary body –> decrease IOP

Question 12

What is pilocarpine commonly used to treat? What class of drugs does it belong to? What is its mechanism for treatment? What are some off-target effects?

Answer 12

treat: glaucoma

class: muscarinic agonist

mechanism: ciliary muscle contraction –> aqueous humor outflow to canal of schlemm (to systemic circulation) –> decrease IOP

off-target effects: miosis, myopia

Question 13

What is physostigmine commonly used to treat? What class of drugs does it belong to? What is its mechanism for treatment? What are some off-target effects?

Answer 13

treat: glaucoma

class: anticholinesterase

mechanism: ciliary muscle contraction –> aqueous humor outflow to canal of schlemm (to systemic circulation) –> decrease IOP

off-target effects: miosis, myopia

Question 14

What are the 2 vasoconstrictor drugs used to treat glaucoma? What receptors do they mainly act on when used to treat glaucoma? Explain the mechanism of treatment?

Answer 14

drugs: adrenaline, apraclonidine

receptor: alpha adrenoreceptor

mechanism: vasoconstriction –> decrease blood clow to ciliary body –> decrease aqueous humor secretion –> decrease IOP

Question 15

What is the mechanism behind cannabinoids being used to treat glaucoma?

Answer 15

relax trabecular network –> decrease IOP

Question 16

Of all the drugs used to treat glaucoma, which one has no significant advantage over other drugs?

Answer 16

cannabinoids

Question 17

What endogenous ligand are cannabinoids related to?

Answer 17

anandamide

Question 18

What receptors do cannabinoids act on?

Answer 18

CB1 and CB2

Question 19

What protein is the CB1 receptor coupled to? Explain its mechanism in relation to the trabecular network.

Answer 19

protein: Gi
mechanism: reduce transmitter release by decreasing Ca2+ influx and opening GIRK channels –> relax trabecular network

Question 20

Which drug is used to dilate the pupil for ocular examination? What class of drugs does it belong to?

Answer 20

atropine (muscarinic antagonist)

Question 21

TRUE or FALSE: the eyes are under both sympathetic tone and parasympathetic tone.

Answer 21

FALSE: the eyes are only under parasympathetic tone.

Question 22

Which 2 drugs are used to test for horner’s syndrome?

Answer 22

cocaine and amphetamine

Question 23

How does cocaine affect the pupil of normal people vs people with unilateral damage to sympathetic nerves or brainstem stroke?

Answer 23

normal with cocaine: pupil dilation
damage with cocaine: the pupil on the side with damage does not dilate

Question 24

Which neuron in the oculo-sympathetic nerve pathway is amphetamine used to check? What will happen to the pupil if this neuron is damaged vs. intact?

Answer 24

neuron 3
damaged: no dilation of pupil
intact: dilation of pupil

Question 25

Which drug is used to check if damage in Horner’s Syndrome is to neuron 1, 2, or 3?

Answer 25

amphetamine