TY - JOUR
T1 - A muscarinic cholinergic antagonist and a dopamine agonist rapidly increase ZENK mRNA expression in the form-deprived chicken retina
AU - Ashby, Regan
AU - McCarthy, C. Siobhan
AU - Maleszka, Ryszard
AU - MEGAW, Pamela
AU - Morgan, Ian G.
PY - 2007/7
Y1 - 2007/7
N2 - Increases in the expression of the immediate early gene ZENK in the retina, measured by changes in the levels of mRNA and protein immunoreactivity, are amongst the most rapid responses so far measured to conditions that decrease the rate of eye growth in chickens. Our aim was to determine whether atropine, a muscarinic cholinergic antagonist, and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide, a dopamine agonist, which are known to block excessive eye growth, produce similar changes in ZENK expression. Form-deprivation resulted in significant down-regulation of the expression of retinal ZENK mRNA within 1 h of fitting the diffusers, whereas removal of the diffusers from the eyes of chickens that had developed form-deprivation myopia resulted in significant up-regulation of retinal ZENK expression within 1 h. When atropine (10 μL of 25 mM solution) and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (10 μL of a 10 mM solution) were injected intravitreally, just prior to fitting the diffusers, the down-regulation of retinal ZENK mRNA caused by form-deprivation was reversed. This resulted in levels of ZENK mRNA higher than in control or contralateral control eyes. The doses were chosen because they are known to block the excessive axial elongation induced by form-deprivation, without affecting the growth of control eyes. Neither agent had any effect on retinal ZENK expression within this time period when injected into control eyes. These results suggest that both muscarinic acetylcholine antagonists and dopamine agonists act early in the signal cascade controlling eye growth, possibly within the retina itself.
AB - Increases in the expression of the immediate early gene ZENK in the retina, measured by changes in the levels of mRNA and protein immunoreactivity, are amongst the most rapid responses so far measured to conditions that decrease the rate of eye growth in chickens. Our aim was to determine whether atropine, a muscarinic cholinergic antagonist, and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide, a dopamine agonist, which are known to block excessive eye growth, produce similar changes in ZENK expression. Form-deprivation resulted in significant down-regulation of the expression of retinal ZENK mRNA within 1 h of fitting the diffusers, whereas removal of the diffusers from the eyes of chickens that had developed form-deprivation myopia resulted in significant up-regulation of retinal ZENK expression within 1 h. When atropine (10 μL of 25 mM solution) and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (10 μL of a 10 mM solution) were injected intravitreally, just prior to fitting the diffusers, the down-regulation of retinal ZENK mRNA caused by form-deprivation was reversed. This resulted in levels of ZENK mRNA higher than in control or contralateral control eyes. The doses were chosen because they are known to block the excessive axial elongation induced by form-deprivation, without affecting the growth of control eyes. Neither agent had any effect on retinal ZENK expression within this time period when injected into control eyes. These results suggest that both muscarinic acetylcholine antagonists and dopamine agonists act early in the signal cascade controlling eye growth, possibly within the retina itself.
KW - ADTN
KW - atropine
KW - axial length
KW - mRNA
KW - myopia
KW - retina
KW - ZENK
KW - Egr1
UR - http://www.scopus.com/inward/record.url?scp=34347343878&partnerID=8YFLogxK
U2 - 10.1016/j.exer.2007.02.019
DO - 10.1016/j.exer.2007.02.019
M3 - Article
C2 - 17498696
AN - SCOPUS:34347343878
SN - 0014-4835
VL - 85
SP - 15
EP - 22
JO - Experimental Eye Research
JF - Experimental Eye Research
IS - 1
ER -