Effect of angiotensin II on the Vogel conflict paradigm and on the content of dopamine and noradrenaline in rat brain.

Abstract

Experiments on male rats were conducted to test the effect of the octapeptide angiotensin II (AT II), introduced intracerebroventricularly (i.c.v.), on a conflict paradigm (drink-foot shock conflict procedure) and on the levels of dopamine and noradrenaline in the hypothalamus and hippocampus during that test. AT II was found to cause substantial reduction of the number of punished responses (biphasically and dose-dependently: the lower dose (0.1 microgram) and the high dose (5 micrograms) have a stronger effect than the moderate doses), which implies a proconflict or anxiomimetic effect. At the same time AT II (1 microgram) caused a substantial reduction of the dopamine level in the hypothalamus and hippocampus. The explanation of the AT II-induced changes in the conflict behaviour (anxiogenic action) is sought in its interaction with the AT II receptors (binding sites) in the brain structures (hypothalamus, hippocampus, etc.), participating in that behaviour, as well as in its modulating effect on the DA-ergic transmission in these structures.