Delayed nootropic effects of arginine vasopressin after early postnatal chronic administration to albino rat pups.

Intranasal administration of arginine vasopressin (10 microg/kg) to albino rat pups had a strong nootropic effect during training with positive and negative reinforcement. This effect was different in animals of various age groups: training with positive reinforcement was improved in "adolescent" rats and pubertal animals, while during training with negative reinforcement, the nootropic effect of the peptide was more prolonged and persisted also in adult animals.

Gaseous superoxide potentiation of the effect of nonnarcotic analgesics in low doses.

The action of inhalation of gaseous superoxide on the effects of low doses of nonnarcotic analgesics was studied on volunteers in the little finger compression test. After administration of placebo, inhalation of gaseous superoxide produced a negligible transient decrease in pain tolerance threshold. Inhalation of gaseous superoxide potentiated the effects of threshold doses of novalgin and aspirin and prolonged their action, but did not modulate the analgesic effect of diclofenac. It is assumed that the potentiating effect of superoxide on the action of analgesics is related to inhibition of monoamine oxidases leading to accumulation of monoamines in the brain.

Improvements in the selective perception and training of rats using an original analog of the C-terminal fragment of vasopressin.

This report presents studies on the effects of intranasal administration of five doses (0.001, 0.01, 0.1, 1, and 10 microg/kg) of a new analog of arginine-vasopressin fragment AVP(6-9), i.e., D-MPRG, on the learning ability of rats with positive and negative reinforcement. All doses of the peptide improved learning. The most effective dose was 0.01 microg/kg, at which the peptide accelerated the acquisition of a conditioned active avoidance reflex both when given 1 h before and when given immediately after training sessions. The peptide had greater effects when animals were trained with negative reinforcement. Analysis of the results suggests that the action of D-MPRG is mainly on perception processes, i.e., extraction of the conditioned stimulus from the environmental surroundings and evaluation and enhancement of its biological significance. In addition, this peptide prevented extinction of the acquired habit and improved the processes of consolidation, though this effect was weaker than its effect on perception.

The effects of a novel analog of the C-terminal fragment of vasopressin on the behavior of white rats.

The effects of an arginine-vasopressin fragment, Ac-D-MPRG, on the movement activity and orientational-investigative activity of white rats were studied. Peptide was given intranasally at doses of 0.001, 0.01, 0.1, 1, and 10 micrograms/kg 1 h before testing. All peptide doses increased vertical movement activity in an open field test and hole board test and decreased grooming levels in both tests. The peptide had no effect on horizontal movement activity. Analysis of these results led to the conclusion that Ac-D-MPRG increases orientational-investigative activity, but, unlike arginine-vasopressin, does not affect non-motivated movement activity.

The effects of analogs of the C-terminal fragment of arginine-vasopressin on the dynamics of development of a conditioned active avoidance response in rats.

This paper reports studies of the effects of original analogs of the C-terminal fragment AVP(6-9), D-MPR and D-MPRG, on the development of a conditioned active avoidance response in rats; agents were given intranasally over a wide range of doses. The most effective does of D-MPR was 0.1 microgram/kg, and the most effective dose of D-MPRG was 0.01 microgram/kg. The tri- and tetrapeptide doses were 10 and 100 times smaller than the dose of arginine-vasopressin used in analogous experimental conditions. The tri- and tetrapeptide accelerated development of the active avoidance conditioned response, affecting both formation of the habit and consolidation of the memory trace. The actions of these peptides were mainly on perception processes, i.e., isolation of the concrete stimulus from the environment, and assessment and remembering of its biological significance.