Amino acids as possible vestibular primary afferent transmitter

Abstract

The vestibular system plays an important role in the control of posture and equilibrium. The system has been extensively investigated an anatomically and electrophysiologically but until now there has been little evidence concerning the chemical neurotransmitters used in this pathway. A knowledge of neurotransmitters is essential for complete understanding of the function and dysfunction of the vestibular system, and is a prerequisite for the design of novel pharmacological agents with which to combat many neurological disorders. Here we have used neurochemical approach to identify possible neurotransmitters used by vestibular pr imary afferents measurement of endogenous amino ac ids released in perfusate after high potassium depolarization and electrical stimuli. The vestibular nucl ear complex was perfus ed w ith artificial cerebra- spinal fluid using a push-pull cannula. The endogenous amino acids release in the perfused was determined by high - performance liquid chrom atography (IIPLC) combin ed with fluorimetric derivatives. Both stimulation of vestibular nerve and perfusion with high potassium, CSF (100 mM) produced significant increase in glutamate and aspartate contents recovered in the perfusate. This result suggests that glutamate and/or aspartate may be neurotransmitters of the vestibular primary afferents.