Ec. Azmitia et al., CELLULAR-LOCALIZATION OF THE 5-HT1A RECEPTOR IN PRIMATE BRAIN NEURONSAND GLIAL-CELLS, Neuropsychopharmacology, 14(1), 1996, pp. 35-46
Activation of 5HT(1A) receptors produces many different physiologic re
sponses, which may be due to their localization on diverse cells in th
e brain. A 5-HT1A receptor antipeptide (aa170-186) antibody was produc
ed that showed both high titer for peptide binding and immunocytochemi
cal staining. Studies performed in perfusion-fixed brain tissue showed
immunoreactive neurons, glial, and ependymal cells in the rat, mouse,
cat, and monkey. Results from our studies of Macaca fascicularis brai
ns are presented. We observed two main neuronal labeling patterns in t
he primate brain: (1) A general, diffuse somatodendritic distribution
of 5-HT1A receptor immunoreactivity is seen in the raphe nuclei where
the dendritic shaft, its branches and spines, and the entire perikaryo
n are immunolabeled. This pattern is also observed in the nucleus locu
s coeruleus, in scattered large brainstem reticular neurons, and in de
ntate gyrus hilar interneurons. (2) A discrete localization of 5-HT1A
receptor immunoreactivity on the initial axon segment (axon hillock) i
s noted in pyramidal neurons of layer III and V of cerebral cortex, Co
rnu Ammonus (1-4) of the hippocampus, and in most brainstem and cervic
al spinal cord motoneurons. In addition to neuronal labeling, 5-HT1A r
eceptor immunoreactivity is seen in the cell body and processes of ast
rocytes, and other nonneuronal cells. This pattern is particularly evi
dent in the white matter of cerebral cortex and spinal cord, the ponti
ne nuclei, the brainstem tectum, and the hilus of the dentate gyrus. T
he clinical implications of 5-HT1A cellular localization are briefly d
iscussed.