Hk. Kia et al., IMMUNOCYTOCHEMICAL LOCALIZATION OF SEROTONIN(1A) RECEPTORS IN THE RATCENTRAL-NERVOUS-SYSTEM, Journal of comparative neurology, 365(2), 1996, pp. 289-305
Specific anti-rat 5-hydroxytryptamine(1A) (serotonin(1A)) receptor ant
ibodies raised in a rabbit injected with a synthetic peptide correspon
ding to a highly selective portion of the third intracellular loop of
the receptor protein (El Mestikawy et al. [1990] Neurosci. Lett. 118:1
89-192) were used for immunohistochemical mapping of serotonin(1A) rec
eptors in the brain and spinal cord of adult rats. The highest density
of immunostaining was found in limbic areas (lateral septum, CA1 area
of Ammon's horn and dentate gyrus in the hippocampus, and frontal and
entorhinal cortices), in the anterior raphe nuclei, and in the interp
eduncular nucleus, in agreement with previous autoradiographic studies
with selective radioligands showing the enrichment of these regions i
n serotonin(1A) receptor binding sites. Serotonin(1A) receptor-like im
munoreactivity was also present, but at a moderate level, in the neoco
rtex, in some thalamic and hypothalamic nuclei, in the nucleus of the
solitary tract, in the dorsal tegmentum, in the nucleus of the spinal
tract of the trigeminal nerve, and in the superficial layers of the do
rsal horn in the spinal cord. In contrast, extrapyramidal areas, inclu
ding the caudate putamen, the globus pallidus, and the substantia nigr
a as well as the cerebellum, exhibited very low to no immunostaining b
y antiserotonin(1A) receptor antibodies. At the cellular level, both t
he plasma membrane of neuronal perikarya and fine neuronal processes p
robably corresponding to dendritic fields were found to bind antiserot
onin(1A) receptor antibodies. Regional differences were noted regardin
g these two types of immunostaining, because only dendrites bound anti
bodies within the hippocampus and the lateral septum, whereas both den
drites and neuronal cell bodies were immunoreactive in the medial sept
um, in the diagonal band of Broca, and in the dorsal and median raphe
nuclei. Therefore, differential addressing of serotonin(1A) receptors
could occur from one neuron to another. In general, the distribution a
nd density of serotonin(1A) receptor-like immunoreactivity in the whol
e brain and in spinal cord were consistent with the mapping of seroton
in(1A) receptor binding sites and serotonin(1A) receptor mRNA previous
ly established by immunoautoradiographic and in situ hybridization pro
cedures. (C) 1996 Wiley-Liss, Inc.