The effects of bicuculline (0.25 mg/kg i.p.) and AP-7 (5 nmols icv) on the processes of retrieval, consolidation of conditioned reflexes, object recognition and locomotor activity were tested in rats. Neither AP-7, nor bicuculline nor AP-7 with bicuculline changed locomotor and exploratory activity in the open field test. Coadministration of AP-7 with bicuculline however, facilitated retrieval of passive avoidance in rats, but was without effect on consolidation in this test. Also neither AP-7 nor bicuculline when were given alone had an effect on influenced consolidation. We found no differences in effects of either AP-7 or bicuculline on object recognition regardless whether administered alone or in combination.
We investigated the effect of a single 2?g dose of vasopressin (AVP) analogue on the processes of retrieval of conditioned reflexes in rats with experimentally induced amnesia.The models used were: electroconvulsive shock (ECS) and hypoxia.It severely impaired the memory processes.The AVP analogue facilitated retrieval of passive avoidance in all animals.
In this study we tested the hypothesis that nitric oxide (NO), which function as a novel type of inter-cellular messenger in the central nervous system (CNS) participated in the facilitator effect of arginine vasopressin (AVP) on learning and memory. Recent investigations have provided evidences that inhibition of NO synthesis attenuated the vasodilatation caused by AVP, and inhibited the improvement of learning and memory evoked by angiotensin II. AVP as well as pharmacologically produced increase in endogenous NO facilitates the consolidation of shock avoidance learning. We evaluated the behavioural effects of AVP at dose 1 mug after the inhibition of NOS by N(G)-nitro-L-arginine methyl ester (L-NAME) at dose 10 mug, and after the injection of endogenous donor of NO -L-argnine- 10 mug in the retrieval of passive avoidance situation, and in consolidation of active avoidance responses. The locomotor activity of all investigated drugs was tested in the open field test. AVP facilitated the recall of passive avoidance responses and consolidation of active avoidance responses. Neither the increase of NO concentration after the injection of L-arginine nor the decrease of NO after the inhibition of NOS by L-NAME changed the behavioural effects of AVP. L-arginine increased the psychomotor behaviour and L-NAME decreased the activity of animals in the 'open field' test. L-arginine itself improved the consolidation of active avoidance responses. Our results indicate that central action of AVP is probably independent of NO concentration in the brain.