Neonatal administration of the neurotoxin 5,7-dihydroxytryptamine results in synaptic reorganization in the superficial gray layer of the hamster's superior colliculus.
Neonatal subcutaneous administration of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) to hamsters results in a marked depletion of serotonin (5-HT) in cortex and an increase in the concentration of this amine in the superior colliculus (SC). To determine whether this increase was associated with an alteration in the synaptic organization of 5-HT-containing axons in the superficial gray layer of the SC, immunocytochemistry was combined with electron microscopy. In normal adult hamsters, only 4.0% of 500 5-HT-immunoreactive profiles make synaptic contacts in the superficial gray layer of the hamster's SC. In 5,7-DHT-treated animals, examination of 400 individual profiles indicated that 25.5% of 5-HT-positive profiles made synaptic contacts (P < 0.05). Given the recently demonstrated effect of 5-HT on retinotectal transmission in this species, the present results suggest that the functional organization of the SC may also be markedly altered in animals that sustain neonatal 5,7-DHT administration.
Department of Anatomy, Medical College of Ohio, Toledo 43699-0008, USA.
E A
EA
Arce
R W
RW
Rhoades
R D
RD
Mooney
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D006224:Cricetinae; D007124:Immunoenzyme Techniques; D007279:Injections, Subcutaneous; D016253:Microscopy, Immunoelectron; D012701:Serotonin / Q000378:metabolism*; D018490:Serotonin Agents / Q000494:pharmacology*; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure
D018490:Serotonin Agents; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin