Journal of Neuroscience, Vol 5, 167-174, Copyright © 1985 by Society for Neuroscience
Autoradiographic localization of thyrotropin-releasing hormone receptors in the rat central nervous system
S Manaker, A Winokur, WH Rostene and TC Rainbow
We employed quantitative autoradiography to examine the distribution of
thyrotropin-releasing hormone (TRH) receptors in the rat CNS. The binding
of [3H]3-methyl-histidine-TRH [( 3H]MeTRH) to TRH receptors in frozen rat
brain sections was saturable, of a high affinity (Kd = 5 nM), and specific
for TRH analogs. Autoradiograms of [3H]MeTRH binding showed highest
concentrations of TRH receptors in the rhinencephalon, including accessory
olfactory bulb, nuclei of the amygdala, and the ventral dentate gyrus and
subiculum of the hippocampus. Moderate TRH receptor concentrations were
found within the thalamus and hypothalamus, in most regions of the
rhombencephalon, such as the cranial nerve nuclei, and in the substantia
gelatinosa of the spinal cord. Neocortex and basal ganglia contained low
densities of TRH receptors. This distribution correlates well with the
sensitivity of brain regions to the known effects of TRH, and suggests that
TRH receptors may mediate the actions of TRH in the rat CNS.