Asst Prof Dao-Qi Zhang, of the Eye Research Institute, publishes in the Journal of Neurophysiology

Researchers in the laboratory of Assistant Professor Dao-Qi Zhang, of the Eye Research Institute, published an article about the Functional Integrity and Modification of Retinal Dopaminergic Neurons in the rd1 Mutant Mouse: Roles of Melanopsin and GABA in the March 15 issue of the Journal of Neurophysiology (Volume 109, Pages 1589-1599). The abstract is reproduced below.

The progressive loss of rod and cone photoreceptors in human subjects with retinitis pigmentosa causes a gradual decline in vision and can result in blindness. Current treatment strategies for the disease rely on the integrity of inner retinal neurons, such as amacrine cells, that are postsynaptic to photoreceptors. Previous work has demonstrated that a specialized subclass of retinal amacrine cell that synthesizes and releases the key neurotransmitter dopamine remains morphologically intact during the disease; however, the pathophysiological function of these neurons remains poorly understood. Here we examined spontaneous and light-evoked spike activity of genetically labeled dopamine neurons from the retinas of retinal degeneration 1 (rd1) mice. Our results indicated that rd1 dopamine neurons remained functionally intact with preserved spontaneous spiking activity and light-evoked responses. The light responses were mediated exclusively by melanopsin phototransduction, not by surviving cones. Our data also suggested that dopamine neurons were altered during photoreceptor loss, as evidenced by less spontaneous bursting activity and increased light-evoked responses with age. Further evidence showed that these alterations were attributed to enhanced GABA/melanopsin signaling to dopamine neurons during disease progression. Taken together, our studies provide valuable information regarding the preservation and functional modification of the retinal dopamine neuronal system in rd1; this information should be considered when designing treatment strategies for retinitis pigmentosa.

The lead authors on the paper are Cameron Atkinson and Jie Feng. Atkinson is currently in the Biomedical Sciences: Biological Communication PhD program. She earned her BS in Biological Sciences at Michigan Technological University in April 2011, and was recently awarded a travel grant to the ARVO annual meeting. Jie Feng obtained her PhD from the Medical School of Xi'an Jiao Tong University. She is now a visiting scholar in Eye Research Institute.

The paper acknowledges Dr. Douglas McMahon of Vanderbilt University, who will be giving a talk at OU today (noon, 372 SEB), and CBR member Frank Giblin, the director of the ERI. The work was supported by an Oakland University Provost’s Graduate Student Research Award (Atkinson), by the Kwang-Hua Education Foundation (Feng), by the Oakland University Research Excellence Fund (Zhang), and by a Midwest Eye-Banks Research Award (Zhang).