Effects of a high-frequency augmented acoustic environment on parvalbumin immunolabeling in the anteroventral cochlear nucleus of DBA/2J and C57BL/6J mice

Abstract

Neurons in the anteroventral cochlear nucleus (AVCN) of DBA/2J (D2) and C57BL/6J (B6) mice were immunohistochemically labeled for the calcium binding protein parvalbumin (PV). Prior to this, mice were treated for 12 hours nightly with a "high frequency" augmented acoustic environment (HAAE: repetitive bursts of a 70 dB sound pressure level, half-octave noise band centered at 20 kHz). This was done during the period that hearing loss occurs: pre-weaning to 55 days in D2 mice and weaning to 9 months in B6 mice. After HAAE treatment in D2 mice, high-frequency hearing loss was ameliorated and fewer PV-labeled neurons were found in the AVCN compared to untreated controls. HAAE treatment in B6 mice exacerbated high-frequency hearing loss, yet the number of PV-labeled AVCN neurons in treated mice did not differ significantly from that of control mice. The findings suggest that HAAE treatment provides relief from physiological stress caused by deprivation of auditory input from the impaired cochlea.

Acoustic Experience Alters the Aged Auditory System

“…Such studies have reared mice in an AAE (usually a 200ms, 70 dB SPL broadband noise presented at a pulsing 2 Hz rate) for as little as 10 days in some studies to well over a year in others in order to investigate the effects of chronic, low-level acoustic stimulation on the degenerating cochlea and central auditory system (Jeskey & Willott, 2000; Turner & Willott, 1998; Willott & Turner, 1999; Willott et al, 2000, 2005, 2006; Willott & Bross, 2004; Willott, 2009, Willott, Vandenbosche, & Shimizu, 2010). That work has shown that if mice with progressive hearing loss are reared in an AAE, their hearing (as measured by behavior, hair cell counts, ABR thresholds, electrophysiological responses of cells in the inferior colliculus) can be improved significantly.…”

Genetics and Age-Related Hearing Loss

“…Follow-up studies by Turner, Willott, and others revealed substantiating evidence that an AAE can delay key functional and structural aspects of ARHL in the mouse strains with rapid presbycusis, including C57s and DBAs (Willott and Turner 1999 ;Willott and Bross 2004 ;Willott 2009 ;Willott et al 2010 ). In addition, structural improvements induced by the AAE were uncovered in DBAs, including preservation of hair cells and AVCN neurons, and reduction of AVCN volume declines with age (Willott et al 2005 ).…”

Rescuing Auditory Temporal Processing with a Novel Augmented Acoustic Environment in an Animal Model of Congenital Hearing Loss

“…Previous studies have shown that when newborn DBA mice are exposed to broadband sounds daily during 12-hour on/off cycles, improvements are seen in peripheral function (Turner and Willott, 1998;Willott and Turner, 1999), preserving hearing sensitivity and limiting hair cell loss (Willott et al, 2005). The mechanism through which the slowing of the degenerative processes occurs is unknown but perhaps the AAE maintains afferent neuronal input to the central auditory system (CAS) (Willott et al, 2010). AAE exposure also limits neuron loss in the cochlear nucleus (Willott et al, 2005) and expands the frequency range to which IC neurons are sensitive 3 across the dorso-ventral axis compared to non-exposed mice .…”