Intracellular calcium involved in the long-term potentiation induced by securinine in dentate gyrus of anesthetized rats

The effect of nimodipine on securinine-induced long-term potentiation in rat hippocampus was studied. The rise of intracellular calcium during the induction of long-term potentiation was measured using Fura-2/AM - a Ca2+ fluorescent chelator. Results showed that intracerebroventricular injection of nimodipine (4 nmol) blocked the induction of long-term potentiation elicited by securinine (0.4 pmol) and high-frequency stimulation (p < 0.05), but 2-amino-5-phosphonovaleric acid (5 nmol) had no inhibitory effect on securinine-induced long-term potentiation. In addition, securinine-induced intracellular calcium increment was inhibited by nimodipine (10(-6) mol . L-1, p < 0.01), but not by 2-amino-5-phosphonovaleric acid (10(-6) mol . L-1, p > 0.05).