Ibotenic acid decreases thyrotropin-releasing hormone receptor binding in the rat amygdala

Thyrotropin-releasing hormone (TRH) receptor densities in the amygdala were examined with quantitative autoradiography in rats treated with the cellular neurotoxin ibotenic acid (IBO). Microinjections of IBO (10 micrograms) into the right basolateral amygdaloid nucleus (BsA) reduced the concentration of TRH receptors in this nucleus by over 50%, when compared to the contralateral BsA and to vehicle-injected control rats. IBO lesions left amygdaloid terminals intact, as shown by normal levels of presynaptic choline uptake sites. Our results strongly suggest that TRH receptors in the amygdala are predominantly located on cell bodies.