Ontogeny of substance P-containing neurons in relation to serotonin-containing neurons in the central nervous system of the mouse.
In order to begin to investigate the developmental factors influencing co-localized neurotransmitters in the central nervous system, we have studied the ontogenesis of coexisting transmitters, substance P and serotonin, in cells of the medullary raphe of the fetal mouse using double-label immunocytochemistry. The results indicate that initial detection of these neurotransmitters occurs at embryonic day 12 in non-overlapping cell populations. Substance P-like immunoreactivity is first co-localized with serotonin in cells of the caudal medullary raphe (raphe pallidus and raphe obscurus) at embryonic day 13. The percentage of serotonin cells containing substance P was estimated at embryonic day 13 and subsequent gestational ages both by double-label immunofluorescence using fluorescein- and rhodamine-conjugated secondary antibodies and also by the elution technique. Double-label immunofluorescence routinely and reliably yielded the highest proportion of co-localized cells. At embryonic day 13, 89% of serotonin cells contained substance P-like immunoreactivity. A consistently high degree of co-localization occurred throughout embryonic development (87% at postnatal day 3) and into adulthood (87%). Colchicine treatment was required at older ages to elicit these data. Unexpectedly, we found that neurons containing substance P-like immunoreactivity in the piriform cortex and in the hypothalamus transiently expressed serotonin immunoreactivity during normal ontogenesis.
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Department of Biological Sciences, Rutgers University, Newark, NJ 07102.
Jonakait
G M
GM
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002490:Central Nervous System / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D005314:Embryonic and Fetal Development; D007150:Immunohistochemistry; D051379:Mice; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*
D012701:Serotonin; D013373:Substance P