Neuronal localization of specific angiotensin II binding sites in the rat inferior olivary nucleus.
Adult male Sprague-Dawley rats were treated with 3-acetylpyridine, a neurotoxin selective for the inferior olivary nucleus. Following treatment, the rats exhibited deficits in locomotor behavior indicative of destruction in the inferior olivary nucleus. The rats were sacrificed 3 weeks later, and the binding of 125I-sarcosine, isoleucine angiotensin II to brain homogenates and slide-mounted sections of brainstem was determined. Treatment with 3-acetylpyridine significantly decreased specific 125I-sarcosine, isoleucine angiotensin II binding in homogenates of posteroventral brainstem (containing the inferior olivary nucleus) by approximately 50%. Homogenates of dorsal brainstem and hypothalamus-thalamus-midbrain showed no significant changes in specific binding. Treatment with 3-acetylpyridine did not significantly alter the radioligand binding affinity which was determined in the hypothalamus-thalamus-midbrain. Autoradiographic analysis of 125I-sarcosine, isoleucine angiotensin II binding in the brainstem sections indicated that specific angiotensin II binding sites in the inferior olivary nucleus were virtually eliminated by the 3-acetylpyridine treatment. In addition, a comparatively small, but significant, decrease in specific 125I-sarcosine, isoleucine angiotensin II binding occurred in the solitary tract nucleus/dorsal vagal motor nucleus complex. These results indicate that specific angiotensin II binding sites in the inferior olivary nucleus occur exclusively on neuronal perikarya and/or dendrites.
Walters
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DE
Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman 99164-6520.
Speth
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RC
D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000494:pharmacology; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009474:Neurons / Q000378:metabolism*; D009847:Olivary Nucleus / Q000166:cytology / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D011725:Pyridines; C010835:3-acetylpyridine; D000804:Angiotensin II; D015059:1-Sarcosine-8-Isoleucine Angiotensin II