THE EXPRESSION OF TrkA AND ChAT IN THE BASAL NUCLEUS OF MEYNERT IN RATS OF DIFFERENT AGE / 神经解剖学杂志

ABSTRACT

The distribution of TrkA and the postnatal development(PD) of TrkA and ChAT-immunoreactive(-IR) neurons andthe relation between them in the basal nucleus of Meynert of rats were studied with immunohistochemical method. The number,mean profile areas and grey degree of TrkA-IR and ChAT-IR neurons were examined with image analyser. The data revealed thatTrkA-IR neurons were localized in the basal forebrain of rats. TrkA immunostaining was present at PDI, but ChAT was not.ChAT immunostaining was present at PD5. Most densely stained TrkA and ChAT neuronal bodies and fibers were present atPD20, the mean grey degrees of TrkA-IR and ChAT-IR neuronal profiles reached its peak. Both TrkA and ChAT neurons beganto cline at PD30 and maintained a relatively higher level in the adult. However, during aging both TrkA and ChAT-IR neuronsatrophy and became smaller than that in the adult. The number of TrkA-IR and ChAT-IR neurons were decreased by 41.38% and 51.61%; the mean profile areas decreased by 15.7% and 12.8%; and the mean grey degrees by 29.9% and 9.9%, respec-tively. The mean profile areas of TrkA-IR and ChAT-IR neurons from PD5 to aged rats were positively correlated. The resultsindicated that the expression of TrkA was earlier than ChAT. The expression of TrkA and ChAT followed a very similar tempo-ral pattern in the basal nucleus of Meynert from PD5 to aged rats, suggesting that TrkA might participate the regulation ofChAT-IR neuronal development, differentiation, maturation, and ageing. The down-regulation of TrkA and ChAT of aged ratsis associated with neuronal atrophy and loss and may contribute to the pronounced vulnerability of these neurons to degenerationin aging animals and Alzheimer's disease.