THE EXPRESSION OF TrkA AND ChAT IN NEURONS OF THE HORIZONTAL LIMB OF DIAGONAL BAND OF DIFFERENTLY AGED RATS──AN IMMUNOHISTOCHEMICAL STUDY / 解剖学报

ABSTRACT

Objective To investigate the postnatal developmental rule of TrkA and ChAT\|immunoreactive(ChAT\|ir) neurons and the relationship between TrkA and ChAT\|ir neurons in the horizontal limb of diagonal band(HDB) of rats. Methods Immunohistochemistry technique combined with image analyser were used. Results TrkA and ChAT\|ir neurons localized in the neurons of basal forebrain of rats. TrkA immunostaining was present at postnatal day 1(PD1), but ChAT immunostaining was present at PD5 Most densely stained TrkA and ChAT neuronal bodies and fibers were present at PD20, while the mean grey degrees of TrkA and ChAT\|ir neurons reached to the peak. Both TrkA and ChAT began to decline at PD30 and maintain a relatively higher level in the adult. However, during aging both TrkA and ChAT\|ir neurons atrophied and became smaller than that of adult. The number of TrkA and ChAT\|ir neurons decreased 39 8% and 33 3%;the mean areas 15 7% and 12 8%; the mean grey degree values were 29 9% and 9 9%, respectively. The mean areas, grey degrees and numbers of TrkA and ChAT\|ir neurons from PD5 to aged rats had positive correlation. Conclusion The results indicate that the expression of TrkA was earlier than ChAT. The expression of TrkA and ChAT followed a very similar temporal pattern in HDB from PD5 to aged rats, suggesting that TrkA may participate in the regulation of ChAT\|ir neuronal development, differentiation, maturation and aging. The down\|regulation of TrkA and ChAT of aged rats is associated with neuronal atrophy and loss and may contribute to the pronounced vulnerability of these neurons to degeneration in aging animals and Alzheimer disease.\;