title: Inhibition of myopia development in chicks using himbacine: a role for M(4) receptors?
abstract: The success of the M(1)-selective muscarinic antagonist pirenzepine in preventing myopia development in animal models implicates a role for the M(1) receptor. However, the relatively high dose of pirenzepine required may indicate that the drug acts through another receptor subtype. This study examined whether the M(4)-selective antagonist, himbacine, could also prevent myopia. Daily intravitreal injections of himbacine inhibited the inducement of myopia in chick eyes in a dose- dependent manner. Doses < or = 200 microg caused no significant inhibition of induced myopia compared to controls (-13.7 +/- 2.3 vs -16.2 +/- 0.9D, ANOVA p = 0.37), whilst a dose of 800 microg almost completely inhibited the induced myopia (-2.4 +/- 2.0, p < 0.01). Findings demonstrate himbacine is effective at preventing the development of myopia in chick and implicates a role for the M4 receptor.
authors.affiliation: Department of Optometry and Vision Sciences, University of Melbourne, Victoria 3010, Australia.
authors.forename: C L
authors.initials: CL
authors.lastname: Cottriall
authors.forename: H T
authors.initials: HT
authors.lastname: Truong
authors.forename: N A
authors.initials: NA
authors.lastname: McBrien
mesh_terms: D000367:Age Factors; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D002645:Chickens; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005663:Furans; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009216:Myopia / Q000188:drug therapy* / Q000378:metabolism / Q000517:prevention & control*; D009281:Naphthalenes; D010276:Parasympatholytics / Q000494:pharmacology*; D010880:Piperidines; D010890:Pirenzepine / Q000494:pharmacology; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012029:Refraction, Ocular / Q000187:drug effects; D012160:Retina / Q000166:cytology; D012683:Sensory Deprivation; D015349:Vision, Monocular; D014822:Vitreous Body / Q000473:pathology
chemical_list: D000470:Alkaloids; D005663:Furans; D018727:Muscarinic Antagonists; D009281:Naphthalenes; D010276:Parasympatholytics; D010880:Piperidines; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic; D010890:Pirenzepine; C048172:himbacine