Morphological study of the serotoninergic projection pathway from the dorsal raphe nucleus to the parafascicular thalamic nucleus in mice
TIAN Huimin
LI Jia
CHENG Jin
LIU Yaohua
LI Fei
LI Yunqing
Abstract：Objective To investigate the morphological characteristics of the serotoninergic(5-HTergic)projection pathway from the dorsal raphe nucleus(DRN)to the parafascicular thalamic nucleus(PF)in mice.Methods An anterograde virus was injected into the DRN of Sert-Cre mice to observe the efferent projection of 5-HTergic neurons targeting various regions of the central nervous system,particularly the PF.Additionally,the retrograde tracer Fluoro-Gold(FG)was injected into the PF of C57BL/6 mice,combined with immunofluorescence histochemical staining,to observe the distribution of FG retrogradely labeled neurons and 5-HT/FG double-labeled neurons in the DRN.Furthermore,the rabies virus(RV)retrograde trans-monosynaptic tracing system was used to observe the synaptic connection between presynaptic 5-HTergic neurons projecting from DRN to CaMK Ⅱ α-positive postsynaptic neurons within PF in the CaMK Ⅱ α-Cre mice.Results The 5-HTergic neurons in the DRN sent fiber projections to the central nervous system,including the PF.FG retrogradely labeled neurons were distributed across the rostral,middle and caudal segments of the DRN,particularly concentrated in the lateral part of the middle segment.Among those FG-labeled neurons,(31.0±2.6)％ of them were 5-HT/FG double-labeled.The RV retrogradely labeled presynaptic neurons in the DRN were achieved through RV trans-monosynaptic tracing,and(21.9±1.8)％ of these RV retrogradely labeled presynaptic neurons were 5-HT/RV double-labeled in the DRN.Conclusion The 5-HTergic neurons in the DRN sent fiber projections to the PF,and those ascending 5-HTergic projecting fibers form monosynaptic connections with CaMK Ⅱ α-positive neurons in the PF.
Keywords：dorsal raphe nucleusparafascicular thalamic nucleusserotoninergic neuronsCaMK Ⅱ α-positive neuronsmice
Publication Date：2025-12-31
Online Publishing Date：2026-08-26(First online date of this platform, not the publication date of the document)
Pages：8( 1586-1593 )