Postnatal changes in development of serotonin-, neuropeptide Y-, Leu-enkephalin- and substance P- terminals in the rat locus coeruleus; a quantitative immunohistochemical study.
Postnatal developmental changes were investigated in afferent terminals immunoreactive to serotonin (5-HT), neuropeptide Y (NPY), Leu-Enkephalin (ENK) and substance P (SP) within the locus coeruleus from postnatal rat from day 1 (1 D) to 9 week (9 W) adult using immunohistochemical techniques. Quantitative study using a light microscopic image analyzing system revealed that the number of immunoreactive terminals increased after birth to reach a peak at 5 W, then decreased by 26% of this value and stabilized at 7 W; terminals immunoreactive to 5-HT or NPY increased gradually after birth, while those immunoreactive to ENK or SP increased suddenly at 3 W. Electron microscopic analysis revealed similar changes in the total terminal number during development. Synaptic terminals, on the other hand, increased sharply from 1 D to 3 W, then gradually until 5 W, and remained stable thereafter. These results suggest that surplus afferent terminals are eliminated prior to the establishment of afferent innervation and that 5 W postnatal is the critical time for maturation of the afferent system. Electron microscopy also demonstrated morphological characteristics of terminals immunoreactive to each peptide or 5-HT and developmental changes in their characteristics.
D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D004743:Enkephalin, Leucine / Q000378:metabolism*; D005260:Female; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008125:Locus Coeruleus / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*
D009478:Neuropeptide Y; D012701:Serotonin; D013373:Substance P; D004743:Enkephalin, Leucine