Abstract
Abstract: :
Purpose: Dopamine acts as both neurotransmitter and neuromodulator on multiple subtypes of dopaminergic receptors in retina. The acute effects of dopamine receptor activation on retinal light responses have been studied extensively. However, little is known about the long-term effects of dopamine receptor activation in retina. We thought to determine whether the activation of dopamine D1 and D2 receptor affects the functional development of retina and whether dopamine plays important roles in the activity-dependent plasticity in mouse retina. Methods: Mouse retinal light responses were recorded using ERG measurements. Young adult mice lack of dopamine D1 or D2 receptor were used to evaluate the roles of dopamine receptors in the functional development of retina. ERGs were also recorded from D1-/- and D2-/- mice reared in constant darkness from birth to determine whether dopamine plays critical roles in activity-dependent plasticity in moue retina. Results: (1) Normally reared D1-/- mice had decreased amplitude of ERG a-, b-wave and OPs comparing with age-matched controls. The magnitude of the suppression was similar to that of dark rearing produced effects on wild type mice. (2) The ERG a- and b-wave of D2-/- mice reared under normal conditions were the same as that of age-matched controls. However, the OPs amplitude of D2-/- mice was significantly higher than that of controls. (3) Dark rearing D1-/- mice for 35 days from birth produced additional suppression on the amplitude of ERG a-, b-wave and OPs. Dark rearing of D2-/- mice for the same period only decreased the amplitude of ERG waveforms to the same level as that of normal controls. Conclusions: Deletion of dopamine D1 and D2 receptors significantly affects the functional development of mouse retina. Deletion of D1 receptor suppressed both inner and outer retina light responses. This suppression was additive to the dark rearing produced effects. Deletion of D2 receptor, however, selectively enhanced inner retinal light responses without effects on outer retinal light responses. Deletion of neither receptor blocked light deprivation produced effect in mouse retina.
Keywords: dopamine • retinal development • transgenics/knock-outs