Reciprocal serotonergic connections between the hamster median and dorsal raphe nuclei.
The median (MnR), but not the dorsal (DR) raphe, sends a serotonergic projection to the suprachiasmatic (SCN) nucleus. Stimulation of either nucleus by electrode or serotonin agonist yields equivalent effects on circadian rhythmicity. This and other evidence suggests the existence of a functional serotonergic pathway from the DR to the MnR that may participate in circadian rhythm regulation. The present investigation was designed to identify such a connection. Tract tracer studies revealed cells in the DR that project to the MnR, as well as cells in the MnR that project to the DR. Double label immunofluorescence methods demonstrated that some of the cells projecting from either nucleus to the other contain serotonin immunoreactivity. The results support the existence of a reciprocal pathway between the DR and MnR that is at least partially serotonergic.
Tischler
Rebecca C
RC
Graduate Program in Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794, USA.
Morin
L P
LP
D000276:Adjuvants, Immunologic / Q000493:pharmacokinetics; D000818:Animals; D002452:Cell Count; D002772:Cholera Toxin / Q000493:pharmacokinetics; D006224:Cricetinae; D005455:Fluorescent Antibody Technique / Q000379:methods; D008297:Male; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology*; D010835:Phytohemagglutinins / Q000493:pharmacokinetics; D011903:Raphe Nuclei / Q000166:cytology / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D014018:Tissue Distribution
D000276:Adjuvants, Immunologic; D010835:Phytohemagglutinins; C100156:leukoagglutinins, plants; D012701:Serotonin; D002772:Cholera Toxin