Cholinergic drugs alter ciliary muscle response and receptor content.
Topical echothiophate administration to the cynomolgus monkey eye for 5-6.5 months produced marked subsensitivity of the accommodative response to pilocarpine and a 65% decrease in specific high affinity 3H-QNB binding sites (ostensibly indicating muscarinic receptors) in the ciliary muscle. The decrease in 3H-QNB binding sites was quantitatively similar in surgically untouched, totally iridectomized, and ciliary muscle disinserted eyes. Following a 5-month off treatment recovery period, 3H-QNB binding sites increased to more than twice the number in untreated control eyes. In echothiophate-treated eyes whose contralateral eyes had previously received atropine+echothiophate, 3H-QNB binding sites were three to six times more numerous than in other long-term echothiophate-treated eyes, and one to two times more numerous than in untreated controls. Topical pilocarpine administration for 1 day to 7 months reduced ciliary muscle 3H-QNB binding sites by approximately 25%. Alterations in muscarinic receptors during and following cholinergic drug therapy may in part explain the observed subsensitization and recovery of ciliary muscle physiological responses.
Erickson-Lamy
K A
KA
Department of Ophthalmology, Medical Schools, of the University of Wisconsin, Madison, USA.
Polansky
J R
JR
Kaufman
P L
PL
Zlock
D M
DM
D000065:Accommodation, Ocular / Q000187:drug effects; D000287:Administration, Topical; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D002924:Ciliary Body / Q000187:drug effects* / Q000378:metabolism; D004456:Echothiophate Iodide / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D008252:Macaca fascicularis; D008297:Male; D018721:Muscarinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000601:surgery; D009883:Ophthalmic Solutions; D010862:Pilocarpine / Q000008:administration & dosage / Q000494:pharmacology*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012029:Refraction, Ocular
D002800:Cholinesterase Inhibitors; D018721:Muscarinic Agonists; D009883:Ophthalmic Solutions; D011976:Receptors, Muscarinic; D010862:Pilocarpine; D004456:Echothiophate Iodide