title: Alterations in ZENK and glucagon RNA transcript expression during increased ocular growth in chickens.
abstract: OBJECTIVE
  To examine in detail the time-course of changes in Zif268, Egr-1, NGFI-A, and Krox-24 (ZENK) and pre-proglucagon (PPG) RNA transcript levels in the chick retina during periods of increased ocular growth induced by form-deprivation and negative-lens wear. To further elucidate the role of ZENK in the modulation of ocular growth, we investigated the effect of intravitreal injections of the muscarinic antagonist atropine and the dopamine agonist 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (ADTN), both of which block the development of experimental myopia, on the expression of ZENK in eyes fitted with negative-lenses.
  
  
  METHODS
  Myopia was induced by fitting translucent diffusers or -10D polymethyl methacrylate (PMMA) lenses over one eye of the chicken. At times from 1 h to 10 days after fitting of the diffusers or negative lenses, retinal RNA transcript levels of the selected genes were determined by semi-quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). For the pharmacology experiments, -10D lenses were fitted over the left eye of chicks for a period of 1h. Intravitreal injections of atropine (10 mul-25 mM), ADTN (10 mul-10 mM), or a vehicle solution were made immediately before fitting of the lenses.
  
  
  RESULTS
  ZENK RNA transcript levels were rapidly and persistently down-regulated following the attachment of the optical devices over the eye. With a delay relative to ZENK, PPG transcript levels were also down-regulated. Induced changes in gene expression were similar for both form-deprivation and negative-lens wear. When atropine or ADTN were administered immediately before lens attachment, the rapid down-regulation in ZENK RNA transcript levels normally seen following 1 h of negative-lens wear was not seen, and ZENK transcript levels rose above those values seen in control eyes. However, injection of atropine or ADTN into untreated eyes had no effect on ZENK transcript levels.
  
  
  CONCLUSIONS
  Both form-deprivation and negative-lens wear modulated the retinal expression of ZENK and PPG RNA transcripts, with a similar time-course and strength of response. The ability of the tested drugs to prevent the down-regulation of ZENK in both lens-induced myopia (LIM) and form-deprivation myopia (FDM) suggests that atropine and ADTN act directly and rapidly on retinal circuits to enhance sensitivity early in the signaling process. These findings suggest that very similar molecular pathways are involved in the changes in eye growth in response to form-deprivation and negative lenses at 1 h after the fitting of optical devices.
authors.affiliation: Research School of Biology, Australian National University, Canberra, Australia. regan.ashby@anu.edu.au
authors.forename: Regan
authors.initials: R
authors.lastname: Ashby
authors.forename: Peter
authors.initials: P
authors.lastname: Kozulin
authors.forename: Pam L
authors.initials: PL
authors.lastname: Megaw
authors.forename: Ian G
authors.initials: IG
authors.lastname: Morgan
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002645:Chickens / Q000235:genetics* / Q000254:growth & development*; D051766:Early Growth Response Protein 1 / Q000235:genetics* / Q000378:metabolism; D005123:Eye / Q000187:drug effects / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D008297:Male; D009216:Myopia / Q000235:genetics; D052336:Proglucagon / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012030:Refractive Errors / Q000235:genetics / Q000473:pathology; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
chemical_list: D051766:Early Growth Response Protein 1; D012333:RNA, Messenger; D013764:Tetrahydronaphthalenes; C011639:ADTN; D052336:Proglucagon; D001285:Atropine
references.citation: Invest Ophthalmol Vis Sci. 2004 Feb;45(2):402-9
references.pmid: 14744878
references.citation: Curr Eye Res. 2003 Dec;27(6):371-85
references.pmid: 14704921
references.citation: Vis Neurosci. 1994 Mar-Apr;11(2):199-208
references.pmid: 8003448
references.citation: Graefes Arch Clin Exp Ophthalmol. 1997 May;235(5):320-4
references.pmid: 9176681
references.citation: Vis Neurosci. 2002 Nov-Dec;19(6):755-66
references.pmid: 12688670
references.citation: J Comp Neurol. 1998 Mar 16;392(3):273-84
references.pmid: 9511918
references.citation: Exp Eye Res. 1995 Oct;61(4):509-16
references.pmid: 8549693
references.citation: Mol Vis. 2004 Aug 24;10:588-97
references.pmid: 15343149
references.citation: Cell Tissue Res. 2001 May;304(2):175-84
references.pmid: 11396712
references.citation: Bioinformatics. 2003 Jul 22;19(11):1439-40
references.pmid: 12874059
references.citation: Curr Eye Res. 1997 Oct;16(10):992-6
references.pmid: 9330850
references.citation: J Neurochem. 1997 Mar;68(3):1001-10
references.pmid: 9048745
references.citation: Trends Neurosci. 1995 Feb;18(2):66-7
references.pmid: 7537412
references.citation: Neuron. 2004 Aug 19;43(4):447-68
references.pmid: 15312645
references.citation: Neurosci Lett. 1997 Nov 14;237(1):9-12
references.pmid: 9406867
references.citation: Brain Res. 2001 Nov 16;919(1):31-40
references.pmid: 11689160
references.citation: Vision Res. 1994 Jan;34(2):143-9
references.pmid: 8116274
references.citation: Exp Eye Res. 2000 Feb;70(2):153-8
references.pmid: 10655140
references.citation: Prog Retin Eye Res. 2005 Jan;24(1):1-38
references.pmid: 15555525
references.citation: Brain Res. 2002 Dec 27;958(2):297-304
references.pmid: 12470865
references.citation: Exp Eye Res. 2007 Jul;85(1):15-22
references.pmid: 17498696
references.citation: Invest Ophthalmol Vis Sci. 1998 Nov;39(12):2217-31
references.pmid: 9804129
references.citation: Brain Res. 2001 Dec 7;921(1-2):173-82
references.pmid: 11720724
references.citation: Exp Eye Res. 2007 Feb;84(2):266-74
references.pmid: 17101130
references.citation: Neurochem Res. 2000 Jan;25(1):153-62
references.pmid: 10685615
references.citation: J Biol Chem. 1988 Sep 25;263(27):13475-8
references.pmid: 2901414
references.citation: Invest Ophthalmol Vis Sci. 2000 Jun;41(7):1623-8
references.pmid: 10845578
references.citation: Invest Ophthalmol Vis Sci. 2002 Jan;43(1):246-52
references.pmid: 11773038
references.citation: Invest Ophthalmol Vis Sci. 2005 Nov;46(11):3932-42
references.pmid: 16249466
references.citation: Neurosci Lett. 1992 Dec 7;147(2):182-4
references.pmid: 1491805
references.citation: Neuroscience. 1996 Oct;74(3):813-23
references.pmid: 8884777
references.citation: Invest Ophthalmol Vis Sci. 2001 Mar;42(3):575-83
references.pmid: 11222513
references.citation: Exp Eye Res. 2002 Jan;74(1):103-11
references.pmid: 11878823
references.citation: Invest Ophthalmol Vis Sci. 2007 Aug;48(8):3430-6
references.pmid: 17652709
references.citation: Optom Vis Sci. 2004 Feb;81(2):148-55
references.pmid: 15127934
references.citation: Exp Eye Res. 2007 Jan;84(1):100-7
references.pmid: 17094962
references.citation: Regul Pept. 2005 Jun 15;128(2):97-107
references.pmid: 15780429
references.citation: Invest Ophthalmol Vis Sci. 2005 Nov;46(11):3922-31
references.pmid: 16249465
references.citation: Ophthalmic Res. 2001 Mar-Apr;33(2):75-9
references.pmid: 11244351
references.citation: Neurochem Res. 1991 Jun;16(6):705-14
references.pmid: 1791917
references.citation: Ophthalmic Physiol Opt. 1995 Sep;15(5):351-6
references.pmid: 8524553
references.citation: Exp Eye Res. 1991 Jun;52(6):755-8
references.pmid: 1855549
references.citation: J Neurochem. 1993 Mar;60(3):902-7
references.pmid: 8382264
references.citation: Nucleic Acids Res. 2001 May 1;29(9):e45
references.pmid: 11328886
references.citation: Brain Res. 1998 May 25;794(1):48-60
references.pmid: 9630509
references.citation: J Mol Neurosci. 2005;27(3):269-76
references.pmid: 16280596
references.citation: Vision Res. 1995 May;35(9):1175-94
references.pmid: 7610579
references.citation: Vision Res. 1997 Mar;37(6):659-68
references.pmid: 9156210
references.citation: FEBS Lett. 1990 May 7;264(1):117-20
references.pmid: 2338135
references.citation: Vision Res. 1995 May;35(9):1247-64
references.pmid: 7610585
references.citation: J Neurochem. 2005 Dec;95(5):1504-20
references.pmid: 16269010
references.citation: Brain Res. 1995 Oct 16;695(2):110-6
references.pmid: 8556320
references.citation: Optom Vis Sci. 2004 Feb;81(2):137-47
references.pmid: 15127933
references.citation: Exp Eye Res. 2006 Mar;82(3):357-61
references.pmid: 16289045
references.citation: Brain Res Mol Brain Res. 2000 May 31;78(1-2):207-15
references.pmid: 10891604
references.citation: Vision Res. 2007 Jun;47(14):1855-68
references.pmid: 17512028
references.citation: Invest Ophthalmol Vis Sci. 2002 Jul;43(7):2067-75
references.pmid: 12091398
references.citation: Invest Ophthalmol Vis Sci. 2007 Jan;48(1):11-7
references.pmid: 17197510
references.citation: Nat Neurosci. 1999 Aug;2(8):706-12
references.pmid: 10412059