Progressive Deterioration of Central Components of Auditory Brainstem Responses during Postnatal Development of the Myelin Mutant <i>taiep</i> Rat

Abstract

Auditory brainstem responses (ABRs) were evaluated during the postnatal development (P10–P180) of taiep rats, neurological mutants characterized by early abnormal myelin development and subsequent demyelination of the CNS. The disorder is produced by an autosomal recessive mutation trait that affects the oligodendrocytes but not the Schwann cells. After onset of ABRs (P12–P14), taiep rats and their nonaffected heterozygous littermates that served as controls showed a similar pattern of maturation for wave I. The central waves (In–IV) showed significantly longer latencies in the mutants. By P60–P180, the later waves (III and IV) were frequently difficult to discern. From the onset of ABRs, the interpeak latency I–IV, corresponding to the central conduction time (CCT) of the auditory pathway, showed in taiep rats significantly longer values than controls. After an initial reduction, proportional to that of control rats, the CCT value increased progressively during the second month of the mutants’ lives. The electrophysiological results of the present study strongly support the hypothesis that mutation in the taiep rat impairs neuromaturation of the central auditory pathway in the brainstem by affecting the myelination process in the CNS.

Leukoencephalopathy upon Disruption of the Chloride Channel ClC-2

“…A slight decrease in central nerve conduction velocity was, however, evident from increased latencies in ABRs. Similar increases were found in demyelinating mouse models (Roncagliolo et al, 2000) and in patients with subclinical forms of CNS myelopathies (Robinson and Rudge, 1975;Starr, 1978;Elidan et al, 1982).…”

Brain responses to tonal changes in the first two years of life

“…For example, Huttenlocher and de Courten [25] found that the greatest increases in synaptogenesis in the occipital cortex occur between 2.5 and 8 postnatal months; however, this process is relatively slower in the frontal cortex where synapse formation does not reach its maximum density until after 15 postnatal months. Third, influences of myelin development on the morphology of waveforms have been demonstrated in animal studies [26], showing that brain responses can be impaired if the brain is exposed to carbon monoxide during the developmental stage of myelination [27]. Moreover, the number of neurons involved in the sensory processes may vary at different ages.…”

Myelination of the Pig’s Brain: A Correlated MRI and Histological Study

“…Myelination of the nerve fibers is executed by oligodendrocytes [1] and animals with abnormal myelin development or demyelination have severely impaired pathways [2], leading to behavioral defects such as changes in locomotive function or impaired coordination [3]. Unfortunately, in the postnatal development of the CNS of experimental animals, the temporal sequence of myelination has been largely neglected.…”