First characterization of 6-hydroxytryptamine in the rat midbrain by using specific antibodies.
The visualization of serotonin, 5-methoxytryptamine, and tryptamine in the rat midbrain has been made possible by the development of antibodies raised against these conjugated molecules. It has been suggested that 6-hydroxytryptamine (6-HT) might also be a neurotransmitter in this region. To test this hypothesis, 6-HT was synthesized and antibodies were raised in the rabbit. The high avidity (IC50 = 5 x 10(-9) M) and specificity [cross-reactivity ratio between 6-HT-glutaraldehyde (G)-bovine serum albumin (BSA) and 5-HT-G-BSA, the most immunoreactive compound, was 1,500] rendered these antibodies reliable tools for specific molecular detection of 6-HT in the G-fixed tissues. In the dopaminergic region, 6-HT immunoreactivity was noted in the substantia nigra but was particularly intense in the red nuclei, where it seems to be localized in the magnocellular division in the form of large 6-HT neurons. In contrast, there were few 6-HT neurons in the raphe nuclei. Thus, 6-HT may be a new putative neurotransmitter existing in the red nuclei, in addition to the other neurotransmitters already described in this region, in the nigro-rubral pathway, and in the rubral projection from the dorsal raphe nuclei. 6-HT is possibly implicated in motor control and might exert hallucinogenic properties as do other 6-hydroxylated indoleamines.
Laboratoire d'Immunologie et de Pathologie, INSERM CJF 88-13, Université de Bordeaux II, France.
H
H
Dabadie
M
M
Geffard
M C
MC
Charrier
D
D
Locuratolo
C
C
Berrier
J C
JC
Jacquesy
D000818:Animals; D000906:Antibodies / Q000276:immunology; D000915:Antibody Affinity; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008636:Mesencephalon / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives* / Q000378:metabolism; D013194:Staining and Labeling; D014018:Tissue Distribution
D000906:Antibodies; D012701:Serotonin; C027803:6-hydroxytryptamine