The development of the medullary serotonergic system in the piglet.
The anatomy of the 5-HT system in the medulla oblongata is well defined in several vertebrate species, but not in the piglet. A detailed map and developmental profile of this system is particularly important in the piglet because this species increasingly is used as a model for physiological studies of medullary homeostatic control and its disorders in human infancy, especially the sudden infant death syndrome. Tryptophan hydroxylase immunohistochemistry was used to identify 5-HT cells and map their distribution in the medullae of piglets between postnatal days 4 and 30, the putative comparable period to early human infancy. Tritiated (3H)-lysergic acid diethylamide (LSD) binding to 5-HT1A-D and 5-HT2 receptors and 3H-8-hydroxy-2-[di-N-propylamine]tetralin (8-OH-DPAT) binding to 5-HT1A receptors were used to quantify and map the distribution of these serotonin receptors between 4 and 60 postnatal days. The distribution of 5-HT cells was similar to that observed in other vertebrate species, with cell bodies in and lateral to the caudal raphé. Tritiated-LSD and 3H-8-OH-DPAT binding both showed significant age-related changes in select raphé and extra-raphé subnuclei. Taken together, these findings suggest that while the medullary 5-HT cells are topographically in place at birth in the piglet, changes in 5-HT neurotransmission take place during the first 30 days of life, as reflected by changes in patterns of receptor binding. Therefore, the first 30 days of life represent a critical period in the development of the 5-HT system and the homeostatic functions it mediates.
Niblock
Mary M
MM
Department of Physiology, Dartmouth Medical School, 1 Medical Center Drive, Lebanon, NH 03753, USA. mary.niblock@dartmouth.edu
Kinney
Hannah C
HC
Luce
Catherine J
CJ
Belliveau
Richard A
RA
Filiano
James J
JJ
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism / Q000493:pharmacokinetics; D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D001808:Blood Vessels / Q000294:innervation; D002454:Cell Differentiation / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D008238:Lysergic Acid Diethylamide / Q000378:metabolism / Q000493:pharmacokinetics; D008526:Medulla Oblongata / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011869:Radioligand Assay; D011903:Raphe Nuclei / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1 / Q000378:metabolism; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D034421:Sus scrofa / Q000033:anatomy & histology* / Q000254:growth & development; D009435:Synaptic Transmission / Q000502:physiology; D014365:Tryptophan Hydroxylase / Q000378:metabolism
D044263:Receptors, Serotonin, 5-HT1; D044348:Receptors, Serotonin, 5-HT2; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D008238:Lysergic Acid Diethylamide; D014365:Tryptophan Hydroxylase