L-AP4, a potent agonist of group III metabotropic glutamate receptor, decreases central action of angiotensin II.

The study was designed to investigate the role of the activation of class III metabotropic glutamate receptors (mGluRs) in the behavioral activity of angiotensin II (AngII). The experiments were performed on adult male Wistar rats. Stimulation of group III mGluRs was evoked by icv injection of agonist, L-2-amino-4-phosphonobutyric acid (L-AP4) (5 microl of 80 mM solution of L-AP4). Fifteen minutes later, the animals were given icv solution containing 1 nmol of AngII. Memory motivated affectively was evaluated by passive avoidance and active avoidance responses (CARs). Moreover, the speculative influence of the treatment on motor activity was tested in open field. We observed that both compounds did not have significant influence on motor activity of rats in open field test. L-AP4 given alone had no influence on acquisition, consolidation and recall of passive avoidance responses. Examination of influence of L-AP4 on the acquisition and extinction of CAR proved that this compound decreased acquisition of CARs, while it did not alter extinction of these responses. AngII, as repeatedly shown before, greatly increased passive avoidance latency, rate of acquisition of CARs and decreased they extinction. Pretreatment of rats with L-AP4 prevented all above behavioral effects of the AngII administration.