GABA (B) receptor gene expression in monkey thalamus

Abstract

Expression of g-amino butyric acid type B (GABAB) receptor gene transcripts wasexamined in the macaque monkey thalamus by in situ hybridization, using monkey-specificcRNA probes. GABABtranscript expression was widespread and of much higher density in thedorsal thalamus than in the reticular nucleus and other parts of the ventral thalamus and washighest in the epithalamus. In the dorsal thalamus, highest mRNA levels were found in theanteroventral nucleus and in the parafascicular nucleus. Sensory relay nuclei showedmoderate GABABmRNA levels. Neurons of all sizes were labeled, suggesting expression inrelay cells and interneurons, and there was no labeling of neuroglial cells. Following 10-dayperiods of monocular deprivation, levels of GABABmRNA were decreased in the deprivedmagno- and parvo-cellular laminae of the dorsal lateral geniculate nuclei, indicatingactivity-dependent regulation. High levels of GABABreceptors in the dorsal thalamus arelikely to reflect the high density of synaptic inputs from the reticular nucleus while lowexpression in the reticular nucleus implies weak, GABAB-mediated intrareticular inhibition.