COMPENSATORY CHANGES OF GOLDFISH MAUTHNER NEURONS INDUCED BY SENSORY STIMULATION AND BETA-AMYLOID APPLICATION

Abstract

Objective - to study thedendrite structure and formation in goldfish Mauthner neurons under the conditions of neurotoxic action of the 25-35 beta-amyloid fragment and long-term optical or vestibular stimulation of goldfish, which affects the afferent inputs to these neurons. Materials and methods.The study was performed on Mauthner neurons of the goldfish fry (n=13) by the methods of light and electron microscopy. The identification of individual dendrites and the determination of their volumes and synaptic structure were carried out using the virtual 3D images of Mauthner neurons obtained from 3 μm serial sections. The functional state of Mauthner neurons was assessed indirectly on the basis of fish the motor lateralization. Results. Under the influence of beta-amyloid application in combination with subsequent long-term sensory stimulation, the volume of ventral dendrites of Mauthner neurons was decreased, their ultrastructure was damaged, and a portion of synapses degenerated. The degeneration of more active neurons was more significant as compared with less active ones. Newly formed medial dendrites had larger volume and less injured ultrastructure of synapses, than those of the ventral dendrites. In the synapses of the same type, localized on ventral and medial dendrites, the sizes of specialized contacts didn’t differ. Conclusions. Medial dendrite formation is a compensatory response to the dystrophy of ventral dendrites caused by experimental interference

Keywords

Mauthner neurons / dendrites / synapses / beta-amyloid / sensory stimulation

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