Direct projections from serotonergic neurons in the dorsal and median raphe nuclei of midbrain to the suprachiasmatic nucleus in Tupaia belangeri chinensis.
This study investigated the direct serotonergic projections to the suprachiasmatic nucleus (SCN) from the dorsal and median raphe nuclei (DR/MR) of the midbrain in Tupaia belangeri chinensis (TBC) by combined application of retrograde horseradish peroxidase (HRP) tract tracing, immunohistochemistry, and electron microscope techniques. The results provide evidence for the direct projections to the SCN from serotonergic neurons distributed predominantly in the MR (mainly in its lateral portion) and to a lesser degree in the DR (in its ventrolateral portion) more caudally in the midbrain, and the existence of abundant symmetrical and asymmetrical synaptic connections between the serotonergic terminals and the postsynaptic elements in the SCN TBC. The results also revealed that almost all DR neurons projecting to the SCN contained serotonin, whereas about one-half of MR neurons projecting to the SCN were immunoreactive for serotonin.
Su
J D
JD
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031, P.R. China.
Liu
S Y
SY
D000818:Animals; D006735:Horseradish Peroxidase; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009474:Neurons / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000737:chemistry / Q000648:ultrastructure; D011903:Raphe Nuclei / Q000166:cytology*; D012701:Serotonin / Q000032:analysis / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology*; D014417:Tupaia / Q000033:anatomy & histology*
D012701:Serotonin; D006735:Horseradish Peroxidase