Arginine-vasopressin binding sites in rat brain: a quantitative autoradiographic study.

Specific binding sites for arginine-vasopressin (AVP) were detected in rat brain after incubation of tissue sections with [3H]AVP. AVP and two selective AVP antagonists are capable of displacing [3H]AVP with an IC50 in the 10(-8)-10(-7) molar range, while oxytocin and ACTH4-10 were much less effective. The neuroanatomical distribution of [3H]AVP-labeled sites was studied with autoradiography utilizing tritium-sensitive LKB film and computerized densitometry for quantitative analyses of the film images. The highest density of [3H]AVP binding sites was observed in hippocampal regions, the lateral septum, olfactory and amygdaloid nuclei, and the nucleus tractus solitarii (NTS) of the brainstem.