Journal of Neuroscience, Vol 14, 7502-7510, Copyright © 1994 by Society for Neuroscience
Quantitative study of tyrosine hydroxylase protein levels within the somatic area of the rat locus coeruleus during postnatal development
L Bezin, D Marcel, C Rousset, JF Pujol and D Weissmann
Laboratorie de Neuropharmacologie Moleculaire, CNRS-UCBL UMR 105, CERMEP, Lyon, France.
To date only global dosages of tyrosine hydroxylase (TH) protein have been
realized in the locus coeruleus (LC) without discriminating the enzyme
contained in the cell body area from the one in the surrounding neuropil.
The preceding immunohistochemical study (Bezin et al., 1994) revealed a
dramatic plasticity of the cellular expression of TH in the LC during the
postnatal development of the rat. It was therefore necessary to develop a
quantitative biochemical approach, strengthened by a great anatomical
resolution, to follow the developmental evolution of TH levels exactly in
the space containing the coerulean TH- immunoreactive perikarya. In the
present work two biochemical parameters necessary for precisely defining
the phenotypic characterization of TH expression within the rat LC have
been established during the postnatal development at six different stages:
postnatal day 4 (PND4), PND10, PND14, PND21, PND30, and PND42. TH tissue
concentration and content were precisely determined along the caudorostral
extent of the LC within the previously (Bezin et al., 1994) defined spaces
delimited by the TH-containing perikarya. TH tissue concentration remained
quite stable during the postnatal development. TH quantity exhibited few
age-related variations with a transient peak at PND10 and followed the same
evolution as the volume containing the TH-expressing perikarya. The mean
cell contribution to the total quantity of TH measured in the whole LC
showed important age- related fluctuations with a dramatic peak at PND10
followed by a drastic decrease until PND21.(ABSTRACT TRUNCATED AT 250
WORDS)