title: [Effect of pirenzepine on form deprivation myopia in chicks and its possible mechanism].
abstract: OBJECTIVE
  To observe the effect of M1-selective muscarinic antagonist, pirenzepine, on form deprivation myopia and investigate the expression of MMP-2 and its inhibitor TIMP-2 in the fibrous sclera in order to better understand the mechanism by which pirenzepine inhibits myopia.
  
  
  METHODS
  40 chicks after birth one day were divided into 4 groups randomly: I. Control group; II. Form deprivation group; III. Vehicle application group; IV. Pirenzepine injected group. Form deprivation myopia was established in right eyes of group II, III, IV by placement of a translucent occluder. The deprived eyes of group III and IV received daily subconjunctival administration of vehicle PBS and pirenzepine respectively. Optical measures such as refraction, axial length, equatorial diameter were made at the end of the experiment. Total RNA and protein were extracted from the posterior fibrous sclera chicks. The expression of MMP-2 and TIMP-2 mRNA and protein were investigated with RT-PCR and Western blot analysis respectively.
  
  
  RESULTS
  Refraction status, axial length, equatorial diameter of the eyes in pirenzepine injected group were significantly lower when compared with form deprivation group (P < 0.01), but the parameters were higher when compared with normal control group therefore relatively myopic changes were detected. There were no significant difference between drug control and pirenzepine injected group when optical measures and the expression of MMP-2, TIMP-2 were concerned (P > 0.05). The expressions (mRNA and protein) of both MMP-2 and TIMP-2 were significantly different in form deprivation group when compared with normal control group (MMP-2 mRNA increased by 143.51%, P < 0.01; protein increased by 114.60%, P < 0.01; TIMP-2 mRNA decreased by 55.05%, P < 0.01; protein decreased by 53.73%, P < 0.01). In pirenzepine injected group the relative expression of MMP-2 mRNA and protein were decreased obviously by 41.95% (P < 0.01) and by 36.16% (P < 0.01), while TIMP-2 mRNA and protein expression was increased significantly by 72.46% (P < 0.01) and by 53.05% (P < 0.01) respectively compared with the form deprived group.
  
  
  CONCLUSIONS
  Subconjunctivally administration of the M1 selective muscarinic antagonist, pirenzepine, partly prevents or restrains form deprivation induced myopia. It may exert its inhibitory effect by modulating the expression of MMP-2 and TIMP-2 in fibrous sclera.
authors.affiliation: Ophthalmic Institute of Henan Province, Zhengzhou 450003, China.
authors.forename: Shu-zhen
authors.initials: SZ
authors.lastname: Dai
authors.forename: Jun-wen
authors.initials: JW
authors.lastname: Zeng
authors.forename: Li-ya
authors.initials: LY
authors.lastname: Wang
mesh_terms: D000287:Administration, Topical; D000818:Animals; D002645:Chickens; D003228:Conjunctiva; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis / Q000235:genetics; D018727:Muscarinic Antagonists / Q000008:administration & dosage*; D009216:Myopia / Q000201:enzymology / Q000517:prevention & control*; D010890:Pirenzepine / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000096:biosynthesis; D011897:Random Allocation; D012590:Sclera / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D012683:Sensory Deprivation; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000096:biosynthesis / Q000235:genetics
chemical_list: D018727:Muscarinic Antagonists; D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2; D010890:Pirenzepine; D020778:Matrix Metalloproteinase 2