Inhibition of the vasopressin-enhancing effect on memory retrieval and relearning by a vasopressin V1 receptor antagonist in mice.
We have previously shown that [Arg8]vasopressin bilaterally administered into the ventral hippocampus of mice at a dose of 0.025 ng/animal 10 min prior to the retention session, improved long-term retrieval processes and relearning of a Go-No-Go visual discrimination task. The purpose of the present study was to determine whether the vasopressin V1 receptor antagonist, -beta-mercapto-beta,beta-cyclopentamethylenepropionyl1, O-Me-Tyr2,Arg8]vasopressin, d(CH2)5Tyr(Me)vasopressin), is able to block the behavioral effect of arginine-vasopressin in the ventral hippocampus. We first tested the effect of three doses of d(CH2)5Tyr(Me)vasopressin (0.025, 1, and 6.3 ng/animal) in the same experimental conditions as used for arginine-vasopressin. The results showed a dose-dependent deleterious effect of the vasopressin V1 receptor antagonist on retrieval and relearning, suggesting the involvement of endogenous arginine-vasopressin in the ventral hippocampus for these memory processes. Second, we tested the ability of d(CH2)5Tyr(Me)vasopressin to block the enhancing effect of experimentally administered arginine-vasopressin. The antagonist was injected at a dose of 0.025 ng, which had no intrinsic effect on behavior, or at a dose of 1 ng, which had a weak deleterious effect on behavior, followed by administration of 0.025 ng of arginine-vasopressin. The results showed that even at the weakest dose (0.025 ng), d(CH2)5Tyr(Me)vasopressin blocked the enhancing effect of arginine-vasopressin on retrieval and relearning. Thus, as for other behaviors and structures, the antagonist microinjected into the ventral hippocampus prevents the enhancing effect of arginine-vasopressin on long-term retrieval and relearning. However, the exclusive involvement of the vasopressin V1 receptors remain to demonstrate vis-a-vis oxytocin receptors.
Alescio-Lautier
B
B
Laboratoire de Neurobiologie des Comportements, URA CNRS 372-Universitede Provence, Marseille, France.
Rao
H
H
Paban
V
V
Devigne
C
C
Soumireu-Mourat
B
B
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects; D007858:Learning / Q000187:drug effects*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009043:Motor Activity / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects*
D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin; C025043:vasopressin, 1-(1-mercaptocyclohexaneacetic acid)-2-(O- methyl-L-tyrosine)-8-L-arginine-