Salvatore L. Stella, Jr., Ph.D.
Assistant Professor of Ophthalmology and Basic Medical Sciences
University of Nebraska Medical Center, Omaha, NE
San Diego State University, San Diego, CA
Light and dark adaptation allow the retina to operate efficiently over a large range of light intensities, with photoreceptors serving as the first step in this process. However, the mechanisms mediating these processes at the first synapse are poorly understood. Studies in our lab have focused on adenosine as a neuromodulator at rod and cone photoreceptors, which have firmly established that adenosine suppresses photoreceptor transmitter release, and favors elevated levels of adenosine in dark adapted conditions. However, major gaps remain in our understanding of adenosine formation and signaling and how adenosine influences adaptation in the retina. Adenosine formed from ATP and functions as a key signaling molecule involved neuronal communication in the retina. Thus, one common theme is purinergic signaling by ATP and adenosine and their roles in vision and visual processing. The overall goal of research in the Stella lab is aimed at understanding how visual information is captured by photoreceptors and processed by retinal circuits, thus our research efforts are targeted at the investigation of retinal circuitry and neurochemical signaling in both normal and diseased retinas. The roles of ATP and adenosine are investigated in several different functional contexts such as: (1) regulation of neurotransmitter release from photoreceptors; (2) how conditions of illumination influence ATP and adenosine release and signaling from the retina; (3) how do purines modulate and influence the adaptation state of the retina; and (4) what role does the balance of purines, ATP versus adenosine play in degeneration of photoreceptors in AMD and the degeneration of retinal ganglion cells in a disease like glaucoma. In addition, recent studies also involve the application of a variety of molecular and imaging techniques to analyze mechanisms involved in the regulation of neurotransmitter release from horizontal cells.
Stella, S.L., Jr., Hu, W.D., Brecha, N.C. (2007) Adenosine inhibits voltage-dependent Ca2+ influx in cone photoreceptor terminals of the tiger salamander retina., J. Neurosci. Res., 85(5), 1126-1137. PMID: 17304584.
Stella, S.L., Jr., Li, S., Sabatini, A., Vila, A., & Brecha, N.C. (2008) Comparison of the ontogeny of the vesicular glutamate transporter 3 (VGLUT3) with VGLUT1 and VGLUT2 in the rat retina., Brain Res., 1215, 20-29. PMID: 18482716.
Barranco, W. T., Kim, D.H., Stella, S. L. Jr., & Eckhert, C. D. (2008) Boric acid inhibits stored Ca(2+) release in DU-145 prostate cancer cells., Cell. Biol. Toxicol. 25(4), 309-20., doi: 10.1007/s10565-008-9085-7. PMID: 18516691.
Guo, C., Stella, S. L., Jr., Hirano, A. A., & Brecha, N. C. (2009) Plasmalemmal and vesicular GABA transporter expression in the developing mouse retina., Journal of Comparative Neurology, 512(1), 6-26. PMID: 18975268.
Stella, S. L., Jr., Hu, W.D., & Brecha, N. C. (2009) Adenosine suppresses exocytosis from cone terminals of the salamander retina, Neuroreport 20(10), 923-9. PMID: 19491713.
Henderson, D.H., Stella, S. L. Jr., Kobylewski, S., & Eckhert, C. D. (2009) Receptor activated Ca(2+) release is inhibited by boric acid in prostate cancer cells. PLoS One. 23(4),e6009. PMID: 19554099.
Guo, C., Hirano, A.A., Stella, S.L. Jr., Bitzer, M., & Brecha, N.C. (2010) Guinea pig horizontal cells express GABA, the GABA-synthesizing enzyme GAD 65, and the GABA vesicular transporter. J Comp Neurol. 518(10), 1647-69. PMID: 20235161.
Mercer A.J., Rabl K., Riccardi, G.E., Brecha, N.C., Stella, S.L. Jr., & Thoreson, W.B. (2011) Location of release sites and calcium-activated chloride channels relative to calcium channels at the photoreceptor ribbon synapse. J Neurophysiol. 105(1), 321-35. PMID: 21084687.
Kao, L., Kurtz, L.M., Shao, X., Papadopoulos, M.C., Liu, L., Bok, D., Nusinowitz, S., Chen, B., Stella, S.L., Andre, M., Weinreb, J., Luong, S.S., Piri, N., Kwong, J.M., Newman, D., & Kurtz,. I. (2011) Severe neurologic impairment in mice with targeted disruption of the electrogenic sodium bicarbonate cotransporter NBCe2 (Slc4a5 gene). J Biol. Chem., 286(37), 32563-74. PMID: 21705333.
Stella, S. L., Jr., Vila, A., Hung, A.Y., Rome, M., Kreienkamp, HJ, Huynh, U, Sheng, M., and Brecha, N. C. (2012) Shank 1 is expressed at cone but not rod synaptic terminals in mammalian retina, PLOS One, 7(9):e43463. PMID: 22984429