Braszko J J, Kupryszewski G, Witczuk B, Wiśniewski K
Department of Pharmacology, Medical Academy, Białystok, Poland.
Neuroscience. 1988 Dec;27(3):777-83. doi: 10.1016/0306-4522(88)90182-0.
Angiotensin II-(3-8)-hexapeptide, at the dose of 1 nmol given intracerebroventricularly, only slightly less than angiotensin II (the same dose and route) stimulated exploratory locomotor behaviour in an open field and electromagnetic motimeter. Both peptides considerably enhanced stereotyped behaviour produced by apomorphine and amphetamine. Angiotensin II-(3-8)-hexapeptide improved recall in a passive avoidance situation as well as angiotensin II. The 3-8 C-terminus of angiotensin II enhanced acquisition of active avoidance nearly as effectively as the complete peptide. The results indicate that the effectiveness of equimolar doses of angiotensin II-(3-8)-hexapeptide and angiotensin II in improving processes related to learning and memory in rats is almost identical and thus must be independent of specific angiotensin receptors in brain to which the hexapeptide binds with about 1000 times lower affinity than angiotensin II. The stimulation of stereotypy, a dopamine-controlled behaviour, by the peptides points to the possibility of dopaminergic mediation of their psychotropic effects.
血管紧张素II-(3-8)-六肽，脑室内注射剂量为1纳摩尔时，在旷场和电磁运动计中刺激探索性运动行为的作用仅略低于血管紧张素II（相同剂量和给药途径）。两种肽均显著增强了阿扑吗啡和苯丙胺产生的刻板行为。血管紧张素II-(3-8)-六肽在被动回避情境中改善记忆的效果与血管紧张素II相同。血管紧张素II的3-8 C末端增强主动回避行为获得的效果几乎与完整肽一样有效。结果表明，等摩尔剂量的血管紧张素II-(3-8)-六肽和血管紧张素II在改善大鼠学习和记忆相关过程方面的有效性几乎相同，因此其作用必定不依赖于该六肽以比血管紧张素II低约1000倍的亲和力与之结合的脑内特定血管紧张素受体。肽类对刻板行为（一种受多巴胺控制的行为）的刺激表明其精神otropic作用存在多巴胺能介导的可能性。
