Serotonergic and non-serotonergic projections from the raphe nuclei to the piriform cortex in the rat: a cholera toxin B subunit (CTb) and 5-HT immunohistochemical study.
Retrograde axonal transport of the cholera toxin B subunit (CTb) was combined with 5-HT immunohistochemistry to determine the origin of the serotonergic innervation of the piriform cortex (PC) in the rat. After iontophoretic CTb injections in the PC, a substantial number of retrogradely labeled cells were found in the middle and medio-ventral part of the dorsal raphe nucleus (RD). A few retrogradely labeled cells were also observed in the median raphe nucleus (MnR) and the B9 serotonergic cell groups. Following CTb and 5-HT immunohistochemistry on the same sections, double-labeled cells were observed in the RD, MnR and B9 groups. In the RD, 30% of CTb stained cells were immunoreactive to 5-HT. After colchicine or nialamide (a monoamine oxidase inhibitor) pretreatment the percentage of these double-labeled cells reached 70%. These results indicate that both 5-HT and non-5-HT neurons in the RD innervate the PC and that the percentage of double-labeled cells is influenced by drug pretreatment. To determine the terminal fields of the RD efferent fibers in the PC, injections of the anterograde tracer PHA-L were also performed. Analysis of the fiber distribution in the PC further revealed some medio-lateral and antero-posterior differences.
Datiche
F
F
Université Claude Bernard Lyon I/CNRS URA 180, Villeurbanne, France.
Luppi
P H
PH
Cattarelli
M
M
D000818:Animals; D002540:Cerebral Cortex / Q000737:chemistry / Q000166:cytology*; D002772:Cholera Toxin; D003078:Colchicine; D007150:Immunohistochemistry; D008297:Male; D009434:Neural Pathways; D009526:Nialamide; D010835:Phytohemagglutinins; D011903:Raphe Nuclei / Q000737:chemistry / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000032:analysis; D017366:Serotonin Receptor Agonists / Q000032:analysis*; D013194:Staining and Labeling
D010835:Phytohemagglutinins; D017366:Serotonin Receptor Agonists; C100156:leukoagglutinins, plants; D012701:Serotonin; D002772:Cholera Toxin; D003078:Colchicine; D009526:Nialamide