XIII Cochlear Potentials and VIII Nerve Action Potentials in Normal and Genetically Deaf Mice

Abstract

ΧΙΠ Certain strains of mice have hereditary lesions of the inner ear, some present at birth, others developing postnatally, which offer an opportunity to study the physiological characteristics of degenerative deafness. Gruenberg et al.' have made observations on cochlear potentials of the developing Shaker-1 mouse. Mikaelian and Ruben^ reported the cochlear potentials, VIII nerve action potentials and responses from single units of the VIII nerve during the development and degeneration of hearing in the Shaker-1 mouse. This was correlated with histology and behavioral response. DeoP ° studied the histolog ical appearance of the labyrinth and the behavioral response in Shaker-1, Varitint-waddler and df/df mice.In this study the parameters for the physiological acoustical responses were determined in the normal mice and the results were then compared to those of the deaf mice. METHODThe mice used in the present experiments were of four types, a normal group of CBA-J strain and three deaf groups, Shaker-1, Varitint-waddler and the uncomplicated deafness strain, df/df. The

ATP-mediated cell–cell signaling in the organ of Corti: the role of connexin channels

“…For both connexins, expression was evident in several sub-compartments of the cochlear duct even at this early post natal stage that precedes by one week the onset of hearing [32]), in keeping with previous findings (see for example Refs. [23,[59][60][61][62][63][64][65]) and with the notion that intercellular connections by GJ proteins are crucial for maturation of different tissues [66].…”

“…Thus, targeted ablation of Cx26 in the epithelial GJ network of Cx26 OtogCre mice [31] (obtained by crossing Cx26 loxP/loxP mice with Otog-Cre mice line expressing the Cre gene under the control of the murine Otog promoter) induced cell death accompanied by epithelial breaches shortly after the onset of hearing (which, in mice, occurs at P12 [32]), along with progressive and significant hearing loss ranging from 30 to 70 dB. The apoptotic process affected first the two supporting cells that surround the IHCs and later extended to OHCs and supporting cells around them.…”

Acceleration of Age-Related Hearing Loss by Early Noise Exposure: Evidence of a Misspent Youth

“…The inner ear is mature morphologically, and electrophysiologic properties of hair cells and gross cochlear response thresholds have stabilized by 4 weeks, the youngest animals studied here (Mikaelian et al, 1965;Lim and Anniko, 1985;Marcotti et al, 2003;Hafidi et al, 2005). Thresholds in the 8 -16 kHz range are almost identical in 4-versus 16-week-old animals (Fig.…”

Developmental expression of the actin depolymerizing factor ADF in the mouse inner ear and spiral ganglia

“…Whereas the expression became upregulated in the modiolus after hearing onset ( Fig. 2A) which, in mice, occurs at about P10 -12 (Mikaelian et al, 1965;Ehret, 1976), it gradually decreased in the organ of Corti (Fig. 2B).…”