Different Features In Distribution Patterns Of Modulator CGRP And Developmental Plasticity Of Dendroarchitecture In Motoneuron Pools Supplying Soleus And Extensor Digitorum Longus

Motoneurons (Mns) supplying Soleus (SOL,slow-twitch) and Extensor Digitorum Longus (EDL,fast-twitch) are different in many aspects. Until now, it is not clear what's the difference in the distribution patterns of modulator CGRP between SOL Mn and EDL Mn pools and what's the difference in dendroarchitecture development between the SOL Mn and EDL Mn pools. Nor is information on whether the androgen could promote dendritic growth available at hand.To evaluate level of CGRP -like immunoreactivity (CGRP-LI) of Mns, a new tracer was prepared and a novel nonfluorescent double -labelled method established. With this technique, the distribution patterns of CGRP-LI in SOL Mn pool and EDL Mn pool were first confirmed and its plasticity in both Mn pools was studied in detail in the present thesis-Using CB-HRP as a probe with TMB protocol,the problems of dendrites mentioned above were studied and differential vulnerability of SOL Mns'and EDL Mns'dendrites to intrathecal administration of Bay K8644 and dynophin A (1 - 17) was discussed.The present thesis includes 3 units, falling into 10 parts.I . Axoplasmic transport of choleragen B coupled with colloidal gold particles (CB-Au) in different diameter and its use in experimental neuroanatomy1. CB-Au as a new retrograde tracerThe free native colloidal gold is not able to be internalized by neurons and never involved in axonal transport. When coupled with CB,the colloidal gold becomes to be internalized through receptor-mediating endocytosis due to the existence of CB, a ligand of GM, ganglioside (receptor of CB), on the axoplasmic membrane. Whether CB-Au coud be used as a neuroanatomical probe was tested and how efficiently it could label the neurons was evaluated after it was injected in different target sites. In this study we prepared three diameters of colloidal gold particles (5 nm,10 nm and 15 nm respectively) which was coupled with CB.Silver intensification was used to visualized the transported CB -Au. The procedure was very easy. After survival 48 h.retrogradely transported CB -Au was detected in corresponding neurons as black deposits in perikarya and proximal dendrites. Ultrastructurally, the deposits were usually associated with lysosomes, which suggests that CB was stripped from CB -Au in-tracellularly leaving the gold in lysosomes and allowing the CB ,but not GM,-CB -Au to enter dendritic flow like GM₁-CB -HRP.The black granular deposits with transparent backgrand never masked the perikarya under light microscope and did not fade even after long storage of sections. Silver-intensification of CB -Au identified neurons results in a very characteristic labelling pattern that can be easily identified in both darkfield and lightfield microscope.