Noradrenergic control of ocular dominance plasticity in the visual cortex of dark-reared cats.
In the visual cortex of cats which had been dark-reared for several months since the time before natural eye opening, a cortical infusion of 6-hydroxydopamine (6-OHDA), a noradrenaline (NA)-related neurotoxin, partially suppressed a usual shift in ocular dominance following brief monocular lid suture, causing a significant loss of binocular cells. This partial shift in ocular dominance (U-shaped histogram) was also observed typically in the control hemisphere of cats which were subjected to dark-rearing for more than a year. Furthermore, the expected shift in ocular dominance following monocular deprivation was blocked by a direct cortical infusion of D,L-metoprolol, a selective beta 1-adrenergic receptor antagonist. The blockade was not obtained by D-metoprolol, a biologically inert stereo-isomer, under the comparable condition. In contrast, exogenous L-NA gave rise to an obvious shift in ocular dominance toward the non-deprived eye. The present results suggest that the NA-beta 1 adrenoreceptor system was necessary to maintain the ocular dominance plasticity in the visual cortex of dark-reared cats.
Shirokawa
T
T
Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115.
Kasamatsu
T
T
Kuppermann
B D
BD
Ramachandran
V S
VS
D000818:Animals; D002415:Cats; D003624:Darkness; D005074:Evoked Potentials, Visual; D006892:Hydroxydopamines / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine; D014793:Visual Cortex / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology*
D006892:Hydroxydopamines; D016627:Oxidopamine; D009638:Norepinephrine