Up－Regulated miR-224-5p Can Target the Expression of Neuritin in Hearing Loss

Objective: This study screened the differentially expressed miRNAs in the mouse cochlea during hearing loss and explored the relationship between miR-224-5p and Neuritin.Methods: The combination of kanamycin sulfate and furosemide was used to establish a mouse hearing loss model. High-throughput sequencing was used to screen the differentially expressed miRNAs during hearing loss. qRT-PCR was used to identify the expression of differential miRNAs in hearing loss. Western Blot was used to detect the expression of Neuritin protein. Luciferase was used to identify the binding site of miRNA and Neuritin.Results: The expression of miR-224-5p in the mouse cochlea increased during hearing loss (p<0.05). MiR-224-5p mimics can reduce Neuritin protein expression in 293T cells (p<0.05). MiR-224-5p can specifically bind to Neuritin (p<0.05).Conclusion: The expression of miR-224-5p increases in hearing loss and targets the expression of Neuritin

Prenatal electroporation-mediated gene transfer restores Slc26a4 knock-out mouse hearing and vestibular function

The otocyst, an anlage of the inner ear, presents an attractive target to study treatment strategies for genetic hearing loss and inner ear development. We have previously reported that electroporation-mediated transuterine gene transfer of Connexin30, utilizing a monophasic pulse into Connexin30−/− mouse otocysts at embryonic day 11.5, is able to prevent putative hearing deterioration. However, it is not clear whether supplementary gene transfer can rescue significant morphological changes, caused by genetic deficits. In addition, with the transuterine gene transfer technique utilized in our previous report, the survival rate of embryos and their mothers after treatment was low, which became a serious obstacle for effective in vivo experiments. Here, we set out to elucidate the feasibility of supplementation therapy in Slc26a4 deficient mice, utilizing biphasic pulses, optimized by modifying pulse conditions. Modification of the biphasic pulse conditions during electroporation increased the survival rate. In addition, supplementation of the target gene cDNA into the otocysts of homozygous Slc24a4 knockout mice significantly prevented enlargement of the endolymphatic space in the inner ear areas; moreover, it rescued hearing and vestibular function of mice in vivo.

Stimulus Salience Determines the Defensive Behaviors Elicited by Aversively Conditioned Compound Auditory Stimuli

SUMMARYAnimals exhibit distinct patterns of defensive behavior according to their perceived imminence of potential threats. Ethoexperimental [1, 2] and aversive conditioning [3-5] studies indicate that as the probability of directly encountering a threat increases, animals shift from behaviors aimed at avoiding detection (e.g. freezing) to escape (e.g. undirected flight). What are the neural mechanisms responsible for assessing threat imminence and controlling appropriate behavioral responses? Fundamental to addressing these questions has been the development of behavioral paradigms in mice in which well-defined threat-associated sensory stimuli reliably and robustly elicit passive or active defensive responses [6, 7]. In serial compound stimulus (SCS) fear conditioning, repeated pairing of sequentially presented tone (CS1) and white noise (CS2) auditory stimuli with footshock (US) yields learned freezing and flight responses to CS1 and CS2, respectively [6]. Although this white noise-induced transition from freezing to flight would appear to reflect increased perceived imminence due to the US being more temporally proximal to CS2 than CS1, this model has not been directly tested. Surprisingly, we find that audio frequency properties and sound pressure levels, not temporal relationship to the US, determine the defensive behaviors elicited by SCS conditioned auditory stimuli. Notably, auditory threat stimuli that most potently elicit high imminence behaviors include frequencies to which mouse hearing is most sensitive. These results argue that, as with visual threats [8], perceived imminence and resulting intensity of defensive responses scale with the salience of auditory threat stimuli.