A neurophysiological study on neurotoxicity of 2,5-hexanedione. Auditory brainstem responses in rats
2,5‐Hexanedioneの神経毒性に関する神経生理学的研究 ラットにおける聴性脳幹反応

Mamoru HIRATA
1987 Sangyo Igaku  
Conduction disturbances in the central nervous system (CNS) of rats due to 2, 5-hexanedione (2, 5-HD) were examined, using auditory brainstem responses (ABRs). Ten male rats (Jcl-Wistar) were given subcutaneous injection of 2, 5-HD of 300mg/kg/day five days a week for three weeks. For the control group, ten male rats (Jcl-Wistar) were employed. One week after the last ad ministration, ABRs in rats were recorded at the scalp with subcutaneously inserted needle electrodes using the monopolar
more » ... d under anesthesia. Intensity of the click sound stimulation was 25dB and 60dB over the threshold of human hearing level (25dBHL and 60dBHL). Mixed nerve con duction velocity of the caudal nerve (MNCVca) and somatosensory cortical evoked potentials by electrical stimulation at the forepaw and medulla oblongata (SEP and SEP-M) were simultaneously recorded. The significant findings observed in rats administered 2, 5-HD in comparison with the control rats were as follows: 1) Delayed latencies of Ist, IInd, IIIrd, IVth and Vth components of 60dBHL sound ABR and Ist, IIIrd, IVth and Vth components of 25dBHL sound ABR; 2) Increased interpeak latencies (IPLs) between Ist and Vth components, IIIrd and Vth components, and IVth and Vth com ponents of 25dBHL sound ABR and between Ist and Vth components of 60dBHL sound ABR; 3) Delayed latencies of P1 and N1 components of SEP; and 4) Decreased MNCVca. Prolongation of IPL between IVth and Vth components of 25dBHL sound ABR was considered to be conduction disturbance of auditory afferent pathway in CNS. The present results on SEP confirmed the previous finding that nerve conduction function in somatosensory afferent pathway was damaged by 2, 5-HD. The results of ABR indicate that measurement of ABR is a sensitive method to detect early disturbance of nerve conduction in CNS by neurotoxic substances which cause the dying back type axonopathy.
doi:10.1539/joh1959.29.145 fatcat:qigvdpunarberdzplkaf46qtmq