Noise alters guinea pig’s blood-labyrinth barrier ultrastructure and permeability along with a decrease of cochlear Claudin-5 and Occludin

Abstract

BackgroundNoise exposure (NE) is a severe modern health hazard that induces hearing impairment. However, the noise-induced ultrastructural changes of blood-labyrinth barrier (BLB) and the potential involvements of tight junction proteins (TJP) remain inconclusive.We investigated the effects of NE on not only the ultrastructure of cochlea and permeability of BLB but also the expression of TJP within the guinea pig cochlea.ResultsMale albino guinea pigs were exposed to white noise for 4 h or 2 consecutive days (115 dB sound pressure level, 6 hours per day) and the hearing impairments and light microscopic change of BLB were evaluated with auditory brainstem responses (ABR) and the cochlear sensory epithelia surface preparation, respectively. The cochlear ultrastructure and BLB permeability after NE 2d were revealed with transmission electron microscope (TEM) and lanthanum nitrate-tracing techniques, respectively. The potential alterations of TJPs Claudin-5 and Occludin were quantified with immunohistochemistry and western blot. NE induced significant hearing impairment and NE 2d contributed to significant outer hair cell (OHC) loss that is most severe in the first row of outer hair cells. Furthermore, the loosen TJ and an obvious leakage of lanthanum nitrate particles beneath the basal lamina were revealed with TEM. Moreover, a dose-dependent decrease of Claudin-5 and Occludin was observed in the cochlea after NE.ConclusionsAll these findings suggest that both decrease of Claudin-5 and Occludin and increased BLB permeability are involved in the pathologic process of noise-induced hearing impairment; however, the causal relationship and underlying mechanisms should be further investigated.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-014-0136-0) contains supplementary material, which is available to authorized users.

Outcomes of Peptide Vaccine GV1001 Treatment in a Murine Model of Acute Noise-Induced Hearing Loss

“…Hence, this novel peptide vaccine may have additional potential applications in other medical conditions such as sudden sensorineural hearing loss or Meniere disease on the basis of the multipotent actions on the reduction of ROS/RNS, pro-inflammatory mediators and blocking proapoptotic caspases Interestingly, a recent study proposed that noise might loosen the blood-labyrinth-barrier; the highest perilymph concentration of the antioxidant AVN-C was noted 1 h after noise exposure [15]. In another study utilizing a guinea pig model, noise-induced ultrastructural changes in the blood-labyrinth barrier and decreased the immunoreactivities of tight junction proteins, suggesting that noise might affect blood-labyrinth barrier permeability [24]. The significant decreases in oxidative stress levels evident 1 h after PTS-noise exposure in the present study may reflect early antioxidant effects of GV1001 in the cochlea, facilitated by the pharmacodynamics of a loose blood-labyrinth barrier.…”

Pharmacokinetic Properties of Adenosine Amine Congener in Cochlear Perilymph after Systemic Administration

“…Numerous studies have suggested that the disruption of this barrier can result in imbalance of local ionic homeostasis [ 35 , 36 ], reduced drug entry [ 36 ], endolymphatic hydrops [ 40 ], and hearing loss [ 41 ]. A recent study reported the change of blood-labyrinth barrier's permeability after noise exposure [ 42 ]. That study identified leaky tight junctions as a possible cause of increased permeability of the blood-labyrinth barrier in the guinea pigs exposed to noise due to decreased cellular expression of Claudin-5 and Occludin [ 42 ].…”

“…A recent study reported the change of blood-labyrinth barrier's permeability after noise exposure [ 42 ]. That study identified leaky tight junctions as a possible cause of increased permeability of the blood-labyrinth barrier in the guinea pigs exposed to noise due to decreased cellular expression of Claudin-5 and Occludin [ 42 ]. It is possible that noise exposure in our study resulted in leaky tight junctions, leading to a faster ADAC diffusion across the blood-labyrinth barrier.…”

Advances in research on labyrinth membranous barriers

“…Studies implicate PEDF signaling between PVM/Ms and ECs as an important mediator of the effect PVM/Ms have on expression of tight- and adherens-junction proteins such as occludin, ZO-1 and ve-cadherin. Wu et al. (2014) indicated that a large number of tight junction proteins (TJs), including mainly Claudin-5 and Occludin, contributed to the integrity and permeability of BLB by connecting adherens proteins in pericytes and other TJs.…”

“…The membranous labyrinth is divide into different chambers by a barrier system, which separates the endolymph, perilymph, cerebrospinal fluid (CSF) and serum. Previous studies have proposed that membranous labyrinth barriers are blood-labyrinth barriers (BLB), but failed to clearly explain permeability characteristics of each barrier ( Hawkins, 1973 , Juhn and Rybak, 1981 , Ge, 1989 , Yamasoba et al., 1996a , Liu et al., 2013 , Hirose et al., 2014 , Li et al., 2014 , Wu et al., 2014 , Zhang et al., 2015 ). In this review, we propose that the so called BLB (or intra-ear fluid barrier) consists of the blood–endolymph barrier, blood–perilymph barrier, cerebrospinal fluid–perilymph barrier, middle ear–labyrinth barrier and endolymph–perilymph barrier.…”