Histamine H3 receptor-mediated impairment of contextual fear conditioning and in-vivo inhibition of cholinergic transmission in the rat basolateral amygdala.

摘要: We investigated the effects of agents acting at histamine receptors on both, spontaneous release ACh from basolateral amygdala (BLA) freely moving rats, and fear conditioning. Extensive evidence suggests that cognition might be explained by modulation cholinergic systems. Using microdialysis technique in we demonstrated perfusion BLA with histaminergic compounds modulates ACh. The addition 100 mm KCl to medium strongly stimulated release, whereas, 0.5 microm tetrodotoxin (TTX) inhibited more than 50%. Histaminergic H3 antagonists (ciproxifan, clobenpropit thioperamide), directly administered BLA, decreased an effect fully antagonized simultaneous cimetidine, H2 antagonist. Local administration cimetidine alone increased slightly, but significantly. Conversely, H1 failed alter release. Rats receiving intra-BLA, bilateral injections doses similar those inhibiting immediately after contextual conditioning, showed memory consolidation impairment Post-training, 50 microg scopolamine also had adverse retention. These observations provide first are involved tone