title: Both electrical stimulation thresholds and SMI-32-immunoreactive retinal ganglion cell density correlate with age in S334ter line 3 rat retina.
abstract: Electrical stimulation threshold and retinal ganglion cell density were measured in a rat model of retinal degeneration. We performed in vivo electrophysiology and morphometric analysis on normal and S334ter line 3 (RD) rats (ages 84-782 days). We stimulated the retina in anesthetized animals and recorded evoked responses in the superior colliculus. Current pulses were delivered with a platinum-iridium (Pt-Ir) electrode of 75-μm diameter positioned on the epiretinal surface. In the same animals used for electrophysiology, SMI-32 immunolabeling of the retina enabled ganglion cell counting. An increase in threshold currents positively correlated with age of RD rats. SMI-32-labeled retinal ganglion cell density negatively correlated with age of RD rats. ANOVA shows that RD postnatal day (P)100 and P300 rats have threshold and density similar to normal rats, but RD P500 and P700 rats have threshold and density statistically different from normal rats (P < 0.05). Threshold charge densities were within the safety limits of Pt for all groups and pulse configurations, except at RD P600 and RD P700, where pulses were only safe up to 1- and 0.2-ms duration, respectively. Preservation of ganglion cells may enhance the efficiency and safety of electronic retinal implants.
authors.affiliation: Doheny Vision Research Center, Doheny Eye Institute, Los Angeles, CA 90033, USA.
authors.forename: Leanne L H
authors.initials: LL
authors.lastname: Chan
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Lee
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
authors.forename: James D
authors.initials: JD
authors.lastname: Weiland
mesh_terms: D000375:Aging; D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count / Q000379:methods; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods*; D005071:Evoked Potentials / Q000235:genetics / Q000502:physiology; D008027:Light; D009154:Mutation / Q000235:genetics; D016900:Neurofilament Proteins / Q000378:metabolism*; D009474:Neurons / Q000502:physiology; D051381:Rats; D011922:Rats, Mutant Strains; D055647:Rats, Transgenic; D012160:Retina / Q000473:pathology; D012162:Retinal Degeneration / Q000235:genetics / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D012243:Rhodopsin / Q000235:genetics; D012684:Sensory Thresholds / Q000502:physiology*; D013477:Superior Colliculi / Q000166:cytology / Q000502:physiology
chemical_list: D016900:Neurofilament Proteins; C051774:neurofilament protein H; D012243:Rhodopsin