REGIONAL CHANGES IN BETA(1) THYROID-HORMONE RECEPTOR IMMUNOREACTIVITYIN RAT-BRAIN AFTER THYROIDECTOMY

Quantitative [I-125]protein G-based immunohistochemistry was used to m ap the distribution of beta(1) thyroid hormone receptor (TR beta(1)) i n normal and thyroidectomized adult rat brain, using a previously char acterized polyclonal antibody. The distribution of TR beta(1)-like imm unoreactivity in normal brain was largely but not perfectly concordant with previous accounts of TR beta(1) mRNA distribution in rat brain. Thyroidectomy resulted in increased immunolabeling in most brain regio ns (mean increase: 14%, range: -4% to +25%), with statistically signif icant effects being observed in 9 of the 36 brain regions examined. Br ain regions showing the most pronounced effects included the habenular nucleus (+22%), the oriens layer of the hippocampal CA3 region (+24%) , and the lateral geniculate nucleus of the thalamus (+23%). These res ults demonstrate that the TR beta(1) protein in brain is capable of pl astic changes in response to adult-onset alterations in TH levels. The observed pattern of brain regional receptor changes following thyroid ectomy may provide clues for functional effects of thyroid function al terations in adults. (C) 1997 Elsevier Science B.V.