Abstract
To examine the involvement of calcium channel in the regulation of uptake at synapse and retrograde axonal transport of exogenous materials, we measured the amount of retrograde transport of horseradish peroxidase (HRP) in the masseter motoneuron of the rat administered with calcium channel modulators. A mixture of HRP and one out of L-, P- or N-type calcium channel modulators was injected into the rat masseter muscle. After a survival period of 6 hours, 60μm serial cross cryosections of the brainstem were prepared and processed for the HRP reaction. The amount of HRP reaction products in the masseter motoneuron was quantitatively measured using an image processing system. In the animal administered with the P-type calcium channel antagonist, the amount of HRP reaction products was changed and significantly lower than that in the control one without administration of the antagonist. Other three modulators did not affect the amount of HRP reaction products. These results were discussed with the hypothesis that HRP uptake at the synapse of motoneuron is coupled to the recycling process of transmitter.
