Plasticity Of The Central Auditory System With Cochlear Ablation In Mice

Plasticity in the mature mammalian central nervous system is often induced by changes in neuronal activity. This response, called 'activity-dependent plasticity', can involve changes in amino acid neurotransmitters and receptors which, in turn, can reshape neuronal responses and information processing. The auditory system provides an excellent model for examining activity-dependent plasticity, because the level of neuronal activity can be easily manipulated. So recently scientists focused on the plasticity of auditory centre. Auditory centre was changed in modality and function after the animal was deprived of auditory in childhood. Exploring these changes can help us to know more information about the auditory centre function. A stress is the auditory centre neuron apoptosis induced by auditory deprived, the function changes were close to clinic. So we established an auditory deprived animal model and researched the apoptosis of the auditory centre neurons nucleus by several ways. We wanted to know more information about the changes of auditory centre induced by auditory deprived.ObjectiveTo study the neurons apoptosis of auditory centre induced by auditory deprived.Methods1. 100 BABL/c mice were used in the present study. Mice were checked for normal hearing by auditory brainstem response (ABR) prior to the study. The animal were divided into experimental group and control group. The lateral wall of the dorsal and mastoid bulla of the experimental group mice was removed, exposing the cochlea.Then the cochlea was destoried.The two groups mice were also checked by auditory brainstem response after operation. The animals were allowed to survive 4 months. 2.At an early stage in process of apoptosis, phosphatidylserine(PS), a constitutive membrane aminophospholipid normally existed on the membrane's inner surface, is exposed on the outer surface. This change can be detected by the binding of Annexin V. Radiolabeled AnnexinV in vivo imaging was a method for detecting cells apoptosis.3. The brain stems were continuously sectioned. These were stained with HE and NESSIL. We can explored the cochlear nucleus neurons apoptosis situation four months after cochlea ablation.Results1. We can obtained an stable auditory deprived animal model with cochlea ablation.2.40 percents of ⁹⁹Tc^m-AnnexinV in vivo apoptosis imaging were positive. But no obvious biodistribution difference was found between the two groups.3. The number of cochlea nucleus' neurons remarkably decreased four months after operation.Conclusion1. The cochlea ablation was a credible method for establishing the auditory deprived animal model.2.⁹⁹Tc^m-AnnexinV in vivo apoptosis imaging maybe a new method for investigating auditory centre plasticity.3. The auditory deprived induced the neuron of cochlea nucleus apoptosis. It lasted for a long time after operation.