title: Role of connexin channels in the retinal light response of a diurnal rodent.
abstract: Several studies have shown that connexin channels play an important role in retinal neural coding in nocturnal rodents. However, the contribution of these channels to signal processing in the retina of diurnal rodents remains unclear. To gain insight into this problem, we studied connexin expression and the contribution of connexin channels to the retinal light response in the diurnal rodent Octodon degus (degu) compared to rat, using in vivo ERG recording under scotopic and photopic light adaptation. Analysis of the degu genome showed that the common retinal connexins present a high degree of homology to orthologs expressed in other mammals, and expression of Cx36 and Cx43 was confirmed in degu retina. Cx36 localized mainly to the outer and inner plexiform layers (IPLs), while Cx43 was expressed mostly in cells of the retinal pigment epithelium. Under scotopic conditions, the b-wave response amplitude was strongly reduced by 18-β-glycyrrhetinic acid (β-GA) (-45.1% in degu, compared to -52.2% in rat), suggesting that connexins are modulating this response. Remarkably, under photopic adaptation, β-GA increased the ERG b-wave amplitude in degu (+107.2%) while reducing it in rat (-62.3%). Moreover, β-GA diminished the spontaneous action potential firing rate in ganglion cells (GCs) and increased the response latency of ON and OFF GCs. Our results support the notion that connexins exert a fine-tuning control of the retinal light response and have an important role in retinal neural coding.
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Angelina
authors.initials: A
authors.lastname: Palacios-Muñoz
authors.affiliation: Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Escobar
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Alex
authors.initials: A
authors.lastname: Vielma
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Araya
authors.affiliation: Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile.
authors.forename: Aland
authors.initials: A
authors.lastname: Astudillo
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Valdivia
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Isaac E
authors.initials: IE
authors.lastname: García
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile.
authors.forename: José
authors.initials: J
authors.lastname: Hurtado
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schmachtenberg
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile.
authors.forename: Agustín D
authors.initials: AD
authors.lastname: Martínez
authors.affiliation: Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Palacios
keywords: connexins; multi-electrode array (MEA); neural coding; physiology; retina