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Circadian modulation of the structure and function of the Japanese quail retina: Possible role of dopamine
Friday, Sep 25, 1992 La Palms/A RETINA
X ICER Abstracts
CODE: R-15
781
1
SEPTEMBER 25/FRIDAY
CIRCADIAN MODULATION OF THE STRUCTURE FUNCTION OF THE JAPANESE QUAIL RETINA: ROLE OF DOPAMINE
AND POSSIBLE
N.F. Buelow. M.E. Kellv. R.B. Barlow. Jr,
Institutefor Sensor
CHAIRPERSONS:
CHRISTINE BLAZYNSKI (USA) NICHOLAS BRECHA (USA)
PRESENTATION
N.F. Buelow, M.E. Kelly and R.B. Barlow, Jr. (USA)
As in the A&&
and
DewI&
N. Brecha (USA) 3 I Cell cnvpllne tn the Amohlblan R.dJ.m J.S. McReynolds and C-J. Dong (USA) v of Hm U. Janssen-Bienhold
. m . Cells in the Fish and R. Weiler (Germany)
Effects of AdILYim G. Niemeyer (Switzerland)
on Cat R&.a
Syracuse
Unwersity.
13244
EXPRESSION OF LGLUTAMATE DECARBOXYLASE ISOFORM (GAD&c AND CiADrd AND Na+ /GABA TRANSPORTER mRNA.9 IN %-IE a&JLT ANDBEVELOPItiti tiT RI?I’INA. Nichofaam. Departments of Anatomy & Cell Biolo and Medicine, Jules Stein qe Institute, Brain Research Institute and it! URE, UCLA School of Medleine and VAMC-Wadsworth, Los Angeles, CA 90073, USA.
12:40 Ihe Vertebrate Retina A. Bruun and B. Ehinger
Research,
Rod-cone dominance exhibits a circadian rhythm in the Japanese quail retina. In constant darkness (DD), retinal sensitivity (ERG b-wave) is high at night and spectral sensitivity indicates rod dominance. During the day, retinal sensitivity is low and peakspectral sensitivity indicates cone-domi&ce (1). Circadian clock in the wail eve increases retinal melatonin levels at nieht (2) but the role of melatonin is’not uidewtood. In the Xenopus retina melam& in&acts with dopamine via an ocular clock to control cohe length (3) and dopamine appears to modulate rod-cone dominance (4). We bypotbe& that dopamine and melatonin mediate the circadian rod-cone shift in the auail retina. Dopamine antagonists injected in the vitreous during the day shift the retina to the sensitive rod dominated nighttime state. Dopamine agonists injected at night have the opposite effect. Destruction of dopaminergic cells with 6-OH dopamine leaves the retina in the rod dominated state regardless of time of day. Dooamine, thus. armears 10 mediate cone dominance. Retinal structure also e&bits strong circ’abian rhythms. Processes of the retinaI pigment epithelium move proximally during subjective day surrounding ROS and partially surroundine COS which themselves move oroximallv. At nieht. COS and RPE processes move distally exposing ROS and’COS. A circadian-clock controls the structural rhythms; illumination day or night has no detectable effect. Moreover, structural and functional rhythms do not appear correlated. Circadian RPE and retinomotor movements may be invol\sd in retinal homeostasis rather than changes in sensitivity. (1) Uchiyama. H.. et al. 1990. Neurosci. Abst. 16:1333. (2) Underwood, H., eral. 1990. J. Bid. Rhythms. 5349. (3) Pierce, M.E. and1.C. Besharse. 1985. J. Gen. Phys. 86:671 (4) Witkovsky, P. and X. Shi. 1990. Vis. Neurosci. 5:405.
(Sweden)
GABA is a prominent inhibitory transmitter in the vertebrate retina. GABAergic neurons are characterized by the GABA synthetic enzymes, GAD65 and GAD67, and by the high affinity uptake of GABA, which is likely to be mediated by a newly described Na+/GABA transporter. Ihe present study evaluates the expression of GADS and GAD67 mRNAs, and the Na+ /GABA transporter mRNA in the adult and developing rat retina using in situ hybridization histochemistry. Retinal sections were incubated with radiolabeled antisense or sense RNA, washed at high stringency and processed for autoradio aphy. In the adult retina, GADa and GAD0 mRNAs, and the Na+/ 8 ABA transporter mRNA are expressed in numerous cells distributed to the proximal inner nuclear layer (INL) and to the anglion cell layer (GCL), and in some cells located in the inner plexiform f ayer. Signal is absent over the distal INL and outer nuclear layer. The size of the labeled cells and the label@ patterns suggest that most of these cells are amacrine and displaced amacrme cells. In the developing retina, both GAD6 and GADg mRNAs, and the Na+/GABA transporter mRNA are first detected just after birth in the proximal INL and GCL The Na+/GABA transporter mRNA is detected sli Uy earlier than the GAD6 and GAD67 mRNAs. Labeling increases rapid Bh y during the first postnatal week and all three mRNAs are prominent by the beginning of the second postnatal week, several days before eye o ening. These studies support the hypothesis that GABAergic neurons are t%ctional before eye orrung. We thank Drs. A. Tobin and J. Guastella for providing the AD and GAD67 cDNAs, and the Na+/GABA transporter cDNAs, respective p”y. Supported by NE1 grant EY 04067 and VA Medical Research Funds.
THE RELEATIONSHIP BETWEEN LIGHT, DOPANINE AND HORIZONTAL CELL COUPLING IN THE AMPHIBIAN RETINA. McReynolds, J. S., Dong, C-J. The University of Michigan Department of Physiology, Ann Arbor, MI 48109-0622, U.S.A. In mudpuppy retina, electrophysiological measurement of changes in horizontal cell coupling show that the tonic release of dopamine is low in dark-adapted retinas and higher in light-adapted retinas. In dark-adapted retinas brief exposures to light can cause a transient but significant increase in dopamine release. This shortterm modulation of dopamine release by light appears to be mainly if not entirely via the on-pathway (i.e. via on-center bipolar cells) because it is blocked by 2amino-4-phosphonobutyrate (APB), which blocks light responses in on-center but not in off-center bipolar cells. In other species flashing light stimuli are reported to be more effective than steady light (which in some cases was without effect) as a stimulus for dooamine release. This has led to the hvaothesis that _~ ~~~ ~~~~~~ transitions from light to dark stimulate‘dopamine release via the off-pathway. In mudpuppy, however, the effect of flashing light on dopamine release is also blocked bv APB and is thus mediated via the on-pathway. The uncoupling of horizontal cells produced by iight adaptation or by exogenous dopamine alters the receptive field organization of more proximal neurons, which may provide clues as to the relative contribution of inner vs. outer retinal pathways in lateral interactions.
S.226
X ICER Abstracts
CODE: R-15
781
1
SEPTEMBER 25/FRIDAY
CIRCADIAN MODULATION OF THE STRUCTURE FUNCTION OF THE JAPANESE QUAIL RETINA: ROLE OF DOPAMINE
AND POSSIBLE
N.F. Buelow. M.E. Kellv. R.B. Barlow. Jr,
Institutefor Sensor
CHAIRPERSONS:
CHRISTINE BLAZYNSKI (USA) NICHOLAS BRECHA (USA)
PRESENTATION
N.F. Buelow, M.E. Kelly and R.B. Barlow, Jr. (USA)
As in the A&&
and
DewI&
N. Brecha (USA) 3 I Cell cnvpllne tn the Amohlblan R.dJ.m J.S. McReynolds and C-J. Dong (USA) v of Hm U. Janssen-Bienhold
. m . Cells in the Fish and R. Weiler (Germany)
Effects of AdILYim G. Niemeyer (Switzerland)
on Cat R&.a
Syracuse
Unwersity.
13244
EXPRESSION OF LGLUTAMATE DECARBOXYLASE ISOFORM (GAD&c AND CiADrd AND Na+ /GABA TRANSPORTER mRNA.9 IN %-IE a&JLT ANDBEVELOPItiti tiT RI?I’INA. Nichofaam. Departments of Anatomy & Cell Biolo and Medicine, Jules Stein qe Institute, Brain Research Institute and it! URE, UCLA School of Medleine and VAMC-Wadsworth, Los Angeles, CA 90073, USA.
12:40 Ihe Vertebrate Retina A. Bruun and B. Ehinger
Research,
Rod-cone dominance exhibits a circadian rhythm in the Japanese quail retina. In constant darkness (DD), retinal sensitivity (ERG b-wave) is high at night and spectral sensitivity indicates rod dominance. During the day, retinal sensitivity is low and peakspectral sensitivity indicates cone-domi&ce (1). Circadian clock in the wail eve increases retinal melatonin levels at nieht (2) but the role of melatonin is’not uidewtood. In the Xenopus retina melam& in&acts with dopamine via an ocular clock to control cohe length (3) and dopamine appears to modulate rod-cone dominance (4). We bypotbe& that dopamine and melatonin mediate the circadian rod-cone shift in the auail retina. Dopamine antagonists injected in the vitreous during the day shift the retina to the sensitive rod dominated nighttime state. Dopamine agonists injected at night have the opposite effect. Destruction of dopaminergic cells with 6-OH dopamine leaves the retina in the rod dominated state regardless of time of day. Dooamine, thus. armears 10 mediate cone dominance. Retinal structure also e&bits strong circ’abian rhythms. Processes of the retinaI pigment epithelium move proximally during subjective day surrounding ROS and partially surroundine COS which themselves move oroximallv. At nieht. COS and RPE processes move distally exposing ROS and’COS. A circadian-clock controls the structural rhythms; illumination day or night has no detectable effect. Moreover, structural and functional rhythms do not appear correlated. Circadian RPE and retinomotor movements may be invol\sd in retinal homeostasis rather than changes in sensitivity. (1) Uchiyama. H.. et al. 1990. Neurosci. Abst. 16:1333. (2) Underwood, H., eral. 1990. J. Bid. Rhythms. 5349. (3) Pierce, M.E. and1.C. Besharse. 1985. J. Gen. Phys. 86:671 (4) Witkovsky, P. and X. Shi. 1990. Vis. Neurosci. 5:405.
(Sweden)
GABA is a prominent inhibitory transmitter in the vertebrate retina. GABAergic neurons are characterized by the GABA synthetic enzymes, GAD65 and GAD67, and by the high affinity uptake of GABA, which is likely to be mediated by a newly described Na+/GABA transporter. Ihe present study evaluates the expression of GADS and GAD67 mRNAs, and the Na+ /GABA transporter mRNA in the adult and developing rat retina using in situ hybridization histochemistry. Retinal sections were incubated with radiolabeled antisense or sense RNA, washed at high stringency and processed for autoradio aphy. In the adult retina, GADa and GAD0 mRNAs, and the Na+/ 8 ABA transporter mRNA are expressed in numerous cells distributed to the proximal inner nuclear layer (INL) and to the anglion cell layer (GCL), and in some cells located in the inner plexiform f ayer. Signal is absent over the distal INL and outer nuclear layer. The size of the labeled cells and the label@ patterns suggest that most of these cells are amacrine and displaced amacrme cells. In the developing retina, both GAD6 and GADg mRNAs, and the Na+/GABA transporter mRNA are first detected just after birth in the proximal INL and GCL The Na+/GABA transporter mRNA is detected sli Uy earlier than the GAD6 and GAD67 mRNAs. Labeling increases rapid Bh y during the first postnatal week and all three mRNAs are prominent by the beginning of the second postnatal week, several days before eye o ening. These studies support the hypothesis that GABAergic neurons are t%ctional before eye orrung. We thank Drs. A. Tobin and J. Guastella for providing the AD and GAD67 cDNAs, and the Na+/GABA transporter cDNAs, respective p”y. Supported by NE1 grant EY 04067 and VA Medical Research Funds.
THE RELEATIONSHIP BETWEEN LIGHT, DOPANINE AND HORIZONTAL CELL COUPLING IN THE AMPHIBIAN RETINA. McReynolds, J. S., Dong, C-J. The University of Michigan Department of Physiology, Ann Arbor, MI 48109-0622, U.S.A. In mudpuppy retina, electrophysiological measurement of changes in horizontal cell coupling show that the tonic release of dopamine is low in dark-adapted retinas and higher in light-adapted retinas. In dark-adapted retinas brief exposures to light can cause a transient but significant increase in dopamine release. This shortterm modulation of dopamine release by light appears to be mainly if not entirely via the on-pathway (i.e. via on-center bipolar cells) because it is blocked by 2amino-4-phosphonobutyrate (APB), which blocks light responses in on-center but not in off-center bipolar cells. In other species flashing light stimuli are reported to be more effective than steady light (which in some cases was without effect) as a stimulus for dooamine release. This has led to the hvaothesis that _~ ~~~ ~~~~~~ transitions from light to dark stimulate‘dopamine release via the off-pathway. In mudpuppy, however, the effect of flashing light on dopamine release is also blocked bv APB and is thus mediated via the on-pathway. The uncoupling of horizontal cells produced by iight adaptation or by exogenous dopamine alters the receptive field organization of more proximal neurons, which may provide clues as to the relative contribution of inner vs. outer retinal pathways in lateral interactions.
S.226