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Published on: May 10, 2019
THE EFFECT OF HIGH INTENSITY WHITE NOISE ON THE ULTRASTRUCTURE OF AXO-DENDRITIC SYNAPSES IN COLLICULUS INFERIOR OF
N Gogokhia1, N Pochkhidze2, N Japaridze3
11Ilia State University, Tbilisi, Georgia.
Abstract:
Environmental noise is a serious problem for the society and medicine. Chronic loud noise is known to produce numerous adverse effects on different levels of the organism. In addition to behavioral changes, the involvement of different regions of the brain was documented. The analysis of structural modifications provoked by noise in brain give the possibility to suggest that one of the effects of noise may be the alterations in neurotransmission. Therefore, of special interest should be the elucidation of the effects of chronic noise on the fine structure of synapses of brain areas participating in the processing of auditory information. In the present study, using transmission electron microscope. We elucidate the effects of high intensity chronic white noise on the morphology of axo-dendritic synapses, and size and diameter of synaptic vesicles in auditory region, inferior colliculus of adult male cats. Experimental animals were exposed to 100 dB (5-20 kHz) white noise for one hour per day, for 10 consecutive days. On 11th day, after special procedures, the area of interest was examined under electron microscope. In ~ 15% large synaptic terminals the clustering of synaptic vesicles, as well as swelling, partial vacuolization or degeneration of presynaptic mitochondria were detected. Morphometric analysis of docked (with presynaptic membrane) and undocked synaptic vesicle size revealed that docked vesicles are smaller than undocked vesicles. It was observed in both control and experimental animals, however, in experimental animals, such difference was more significant. Such results suggest that due to continuous transmission, the majority of vesicles are unable to replenish their cargo via transporters. Evaluation of synaptic vesicles size undertaken in the current electron microscopic study has advanced the understanding of the pathophysiology of white noise exposure on auditory brain processing regions, in addition to our understanding of fractional neurotransmitter release at the nerve terminal and on overall brain function.
