Abstract: The effect that arginine-8-vasopressin(AVP) facilitates memory consolida-tion in rats and the change in contents of the fifteen free amino acids of thebrain are investigated. 1. A single subcutaneous injection of AVP (2μg/rat) 1 hour prior tothe third acquisition session significantly increases resistance to the extinctionof pole jumping avoidance response. 2. Following AVP treatment,the amount of GABA in both visualareas and hippocampi and that of isoleucine in the hippocampi are decreasedafter the third acquisition session.After the second extinction the differentchange was observed.The amount of threonine in both visual areas andhippocampi and that of glutamate in the hippocampi are lowered,whereas theamount of lysine in the two regions are elevated in comparison with control,but no change in GABA amount occurs. 3. The experimental result of electric stress response shows that theamount of GABA in the hippocampi and that of phenylalanine in the visualareas are lowered as compared to control.The lowered amount of asparticacid in the two regions is observed 1 hour after the administration of AVP,but no significant difference in contents of any free amino acids is presented48 hours after the administration of AVP.

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