Unilateral Cochlear Ablation In Adult Mice Results In Changes In MMP-9and MMP-2Immunostaining In The Cochlear Nucleus

Life constantly provides a very important amount of information to living animals, which is relevant for their survival. Any environmental stimulus (including stimuli from other living species) contains many complementary aspects (e.g. image, sound/noise, odour, temperature) that serve to define it. 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 change in the cochlea nuclear and inferior colliculus. We wanted to know more Information about the changes of auditory centre induced by auditory deprived. Object:To establish auditory deprived animal model with cochlear ablation and to explore the expression of MMP-9and MMP-2in the cochlear nucleus before and after unilateral cochlear ablation.Methods:35BABL/c mice were used in the second study. The animals were divided into seven groups. The lateral wall of the dorsal and mastoid bulla of six group mice was removed, exposing the cochlea. Then the cochlea was destroyed. The animal of the first group was allowed to survive one day. The animal of the second group was allowed to survive three day. The animal of the third group was allowed to survive seven day. The animal of the fourth group was allowed to survive fifteen day. The animal of the fifth group was allowed to survive thirty day. The animal of the sixth group was allowed to survive sixth day. The seventh group was consisted of control animals that did not receive any surgery. The brainstems were continuously sectioned. These were stained with HE. Then the immunohistochemistry was used to observe the expression of MMP-9and MMP-2.Results:We can explore the MMP-9, MMP-2redistribution in the cochlear nucleus after cochlea ablation. MMP-9and MMP-2moved out of neuronal cell bodies of the cochlear nucleus following its total sensory deafferentation by cochlear ablation.Conclusions:Auditory deprivation could cause MMP-9, MMP-2redistribution in the cochlear nucleus. The different reaction time of this two MMPs suggest the possibility that MMP-9and MMP-2differentially contribute to synaptogenesis.