Related Experiment Video

Updated: Oct 27, 2025

Inducement and Evaluation of a Murine Model of Experimental Myopia
07:20

Inducement and Evaluation of a Murine Model of Experimental Myopia

Published on: January 22, 2019

10.2K

Insights into the mechanism by which atropine inhibits myopia: evidence against cholinergic hyperactivity and

Kate Thomson1, Tamsin Kelly2, Cindy Karouta1

  • 1Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Canberra, Australian Capital Territory, Australia.

British Journal of Pharmacology
|July 24, 2021
PubMed
Abstract

Insights

Cholinergic agonists unexpectedly inhibited myopia development in chicks, challenging the idea that cholinergic hyperactivity causes myopia. Atropine

Area of Science:

  • Ophthalmology
  • Neuroscience
  • Pharmacology

Background:

  • Muscarinic antagonist atropine inhibits myopia in humans and animals.
  • This suggests cholinergic hyperactivity may drive myopic growth.

Purpose of the Study:

  • Investigate if cholinergic agonists accelerate ocular growth in chickens.
  • Determine if atropine's antimyopic effects involve dopamine modulation.

Main Methods:

  • Administered muscarinic, nicotinic, and non-specific cholinergic agonists to chicks with form-deprivation myopia (FDM).
  • Measured vitreal dopamine and DOPAC levels in chicks treated with atropine.
  • Assessed if dopamine antagonists block atropine's antimyopic effects.

Main Results:

  • All tested cholinergic agonists inhibited FDM without affecting normal ocular development.
  • Atropine only impacted dopamine and DOPAC levels at the highest dose.
  • Dopamine antagonists did not alter atropine's antimyopic effects.

Conclusions:

  • Cholinergic hyperactivity does not underlie myopic growth; agonists inhibit FDM.
  • Atropine's antimyopic mechanism does not rely on dopamine pathway modulation.
  • Nicotinic agonists show potential for targeted myopia control with fewer side effects.
Keywords:
AChatropinedopaminemyopiarefractive development

More Related Videos

A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice09:26

A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice

Published on: March 23, 2016

19.9K
Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model05:56

Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model

Published on: April 3, 2016

9.1K

Related Concept Videos

Cholinergic Antagonists: Chemistry and Structure-Activity Relationship01:29

Cholinergic Antagonists: Chemistry and Structure-Activity Relationship

Cholinergic antagonists bind to cholinergic receptors and limit the effects of acetylcholine and other cholinergic agonists. Based on the specific cholinergic receptor affinity, these antagonists are classified as muscarinic or nicotinic. Anticholinergics interrupt parasympathetic innervations while sympathetic innervations remain uninterrupted. Muscarinic antagonists are also called 'muscarinic antagonists', 'antimuscarinics', or 'parasympatholytics'. Nicotinic...
2.5K
Direct-Acting Cholinergic Agonists: Pharmacological Actions00:59

Direct-Acting Cholinergic Agonists: Pharmacological Actions

Direct-acting cholinergic agonists exert their pharmacological actions by mimicking the effects of acetylcholine on postsynaptic muscarinic receptors to generate parasympathetic responses. These agents elicit a range of physiological responses, including cardiovascular effects. For example, activation of muscarinic receptors induces bradycardia, decreased cardiac output, reduced peripheral resistance, and consequent hypotension. In the eye, stimulation of M3 receptors leads to smooth muscle...
1.9K
Indirect-Acting Cholinergic Agonists: Pharmacological Actions01:30

Indirect-Acting Cholinergic Agonists: Pharmacological Actions

Indirect-acting cholinergic agonists, also known as anticholinesterases, exert their pharmacological effects by enhancing cholinergic transmission in various body parts, including the neuromuscular junction, autonomic cholinergic synapses, and the brain.
At the neuromuscular junction, these agents work by inhibiting the breakdown of acetylcholine, allowing it to remain bound to the receptor and bind to nearby receptors. This process leads to repetitive firing of the endplate, causing muscle...
1.0K
Direct-Acting Cholinergic Agonists: Pharmacokinetics01:31

Direct-Acting Cholinergic Agonists: Pharmacokinetics

Direct-acting cholinergic agonists, such as synthetic choline esters and naturally occurring alkaloids, exert their effects by enhancing the actions of acetylcholine and stimulating the parasympathetic nervous system. Synthetic choline esters share structural similarities with acetylcholine. For example, they have a positively charged quaternary ammonium or onium group, contributing to their hydrophilic characteristics. As a result, they are poorly absorbed in the body through oral...
1.5K
Indirect-Acting Cholinergic Agonists: Mechanism of Action01:18

Indirect-Acting Cholinergic Agonists: Mechanism of Action

Indirect-acting cholinergic agonists work by interacting with an enzyme called acetylcholinesterase (AChE) in the synaptic cleft. They can be reversible or irreversible inhibitors and have different effects on the enzyme.
Reversible inhibitors like edrophonium bind to a specific part of the enzyme called the anionic catalytic site. They form noncovalent bonds, which means they are not strongly attached to the enzyme. This creates a temporary and less stable enzyme–inhibitor complex,...
2.1K
Direct-Acting Cholinergic Agonists: Therapeutic Uses01:11

Direct-Acting Cholinergic Agonists: Therapeutic Uses

Direct-acting cholinergic agonists have many therapeutic uses in various medical fields. Choline esters, including acetylcholine, have limited clinical utility due to their non-selectivity and short duration of action. Still, acetylcholine and carbachol are applied topically during ophthalmologic surgery to induce miosis. Pilocarpine, a muscarinic and ganglionic stimulator, effectively treats open-angle glaucoma and alleviates xerostomia and dry mouth caused by radiotherapy or Sjögren...
1.1K