ULTRASTRUCTURAL EVIDENCE OF SEROTONINERGIC INNERVATION OF THE SECONDORDER NEURONS ON THE CENTRAL PATHWAY OF THE TRIGEMINAL PROPRIOCEPTION OF THE RAT / 解剖学报

ABSTRACT

Objective To investigate whether the serotonin(5\|HT)\|like immunoreactive axons synapse upon the second\|order neurons on the central pathway of the trigeminal proprioception in the rat. Methods Electron microscopic double\|labeling of retrograde tract\|tracing technique combined with immunohistochemistry. Results Following the injection of wheat germ agglutinin\|horseradish peroxidase (WGA\|HRP) into the dorsomedial part of the principal sensory trigeminal nucleus(Vpdm) of the rat and the immunostaining for 5\|HT, there were neurons retrogradely labeled by WGA\|HRP and axon terminals with 5\|HT\|like immunoreactivity(5\|HT\|LI) in the dorsomedial part of the subnucleus oralis of the spinal trigeminal nucleus and its adjacent lateral reticular formation(Vodm\|LRF).At the electron microscopic level,the 5\|HT\|immunostained axonal profiles were observed to make synaptic contacts with the WGA\|HRP\|labeled neurons.Both the axon\|somatic and axon\|dendritic synapses were found.These synapses were mainly of symmetric type although the asymmetric ones were also seen.Conclusion\ The present results provided a morphologic basis for the serotoninergic terminals which might be involved in the regulatory effect for the trigeminal proprioceptive information transmission.\;[