RATES OF ANTEROGRADE-AND RETROGRADE-TRANSPORT AND DURATION OF PRESERVATION OF HRP IN THE CENTRAL NERVOUS SYSTEM / 解剖学报

ABSTRACT

It has been found by Ju('81)that HRP could be anterogradely transported forlong distances.Based on this fact the rate of anterograde transport was investigatedin the present study,and,at the same time,the rate of retrograde transport and thetime of disappearance of HRP from the labeled sites were observed.Twenty tworabbits,weighing 2～2.2 kg,were used.The HRP was injected into the lower lumbarspinal cord unilaterally.The animals were sacrificed after 12 hours to 7 days andwere processed with benzidine and o-dianisidine.The anterogade labeling in the dorsalaccessory olivary nucleus and the retrograde labeling in the red nucleus and thenucleus raphe pallidus were chosen for study.It was quite unexpected to find that the anterograde and retrograde labelingsparalled each other in time as well as in intensity.They appeared at the same timeand waxed and waned practically in full accord.Labeling of the brainstem firstappeared at 18 hour's survival,reached its peak at the 2nd day,and then graduallyfaded away till at the 7th day when only traces of labeling remained.In the casewhich showed the earliest labeling the distance between the injection site and theobex,which was at about the same level as the most densely labeled parts of thedorsal accessory olivary nucleus and nucleus raphe pallidus,was measured to be 265mm and the rate of transport,the same for anterograde and retrograde transports,was calculated to be more than 350mm per day.Counting from the time of theearliest labeling,HRP was found to remain at the labeled site for as long as 5～6 days.The period of net accumulation of HRP at the labeled sites was about 1 day.Thus,the best survival period would be roughly the time required for HRP to travel thefiber tract plus 1 day.Neurons of the red nucleus and the nucleus raphe pallidus differ greatly intheir morphology,physiology as well as biochemistry.The results in them however,were similar.This,in connection with observations on other nuclei,both anterogr-adely and retrogradely labeled,suggests that the rate of transport and the duration ofpreservation of HRP in the central nervous system are basically the same in differentneuronal systems.