Abstract
Purpose:
Dopamine receptors play important roles in the activity dependent synaptic plasticity in CNS and multiple subtypes of dopamine receptors are expressed by retinal neurons. Our recent study showed that D1 dopamine receptor regulates the developmental enhancement of ERG b-wave and the light response gain between bipolar and ganglion/amacrine cells. In this study, we further determined whether D2 dopamine receptor plays important roles in the activity-dependent development of mouse retina.
Methods:
Mouse retinal light responses were recorded using ERG measurements. Young and adult wild type (WT) mice and mice lacking dopamine D2 receptor were used to evaluate the roles of dopamine D2 receptor in the development of retina. ERGs were also recorded from mice reared in constant darkness to determine whether dopamine D2 receptor plays critical roles in the activity-dependent development of moue retina. The amplitudes, kinetics and response gains of ERG waveforms are quantitatively analyzed.
Results:
1) Opposite to the mutation of D1 dopamine receptor, the amplitude of inner retinal light responses measured as ERG OPs is selectively enhanced in D2-/- mice. 2) Unlike the D1 dopamine receptor mutation which preferentially affects the response gain between b-wave and OPs at the scotopic range, dopamine D2 receptor mutation preferentially enhance the relative strength of OPs evoked by high light intensities (photopic) through selective enhancement of the response gain between b-wave and OPs. 3) The amplitudes of ERG of D2-/- mice are not different from that of age-matched WT mice before eye opening. 4) The amplitude enhancement of inner retinal light responses of D2-/- mice is completely eliminated by light deprivation.
Conclusions:
1) Deletion of dopamine D2 receptor has opposite effect on the inner retinal light response in comparison with D1 dopamine receptor mutation. 2) D2 dopamine receptor preferentially regulates the retinal light responses after eye opening. 3) Effects induced by mutation of D2 dopamine receptor on ERG are light-sensitive.
Keywords: 510 electroretinography: non-clinical •
502 dopamine •
497 development