Interaction of myelin basic protein and 2',3'-cyclic nucleotide phosphodiesterase with mitochondria.

The content and distribution of myelin basic protein (MBP) isoforms (17 and 21.5 kDa) as well as 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase) were determined in mitochondrial fractions (myelin fraction, synaptic and nonsynaptic mitochondria) obtained after separation of brain mitochondria by Percoll density gradient. All the fractions could accumulate calcium, maintain membrane potential, and initiate the opening of the permeability transition pore (mPTP) in response to calcium overloading.

[Evolution of dissociative learning].

This review considers data obtained during the entire research period of state-dependent learning. Understanding of this phenomenon has significantly evolved during the past decades, as a result of the increasing amount of facts revealed while studying state-dependent learning. Consequently, a situation has arisen where different papers may describe same phenomena using different terms.

Dissociated learning using GABAergic drugs.

Experiments on Wistar rats addressed the possibility of dissociated learning using drugs acting directly on brain GABA(B) receptors. A previously suggested hypothesis was tested: that the cholinergic system of the brain plays the decisive role in the mechanisms of dissociative learning. The data obtained here provided evidence that dissociated learning an occur with compounds acting on the GABAergic transmitter system of the brain.

[Dissociated learning with GABAergic drugs].

The possibility of dissociated learning was investigated using drugs which act directly on GABAB receptors of the brain. The earlier proposed suggestion that the cholinergic system plays a key role in the mechanisms of dissociated learning was tested. It was shown in male Wistar rats that dissociated learning was possible with GABAergic drugs.

[Complex perception of stimuli during conditioning].

The review concerns the effects of a variety of stimuli on the reproduction of conditioned reflexes. By the literature data, during conditioning of any type, besides the single stimulus intentionally applied by an experimenter as a conditioned one, an animal perceives the whole complex of stimuli (acoustic, visual, olfactory, algesic, and other exteroceptive, proprioceptive, and interoceptive stimuli), including those of the environment and time of the day during training. Many of these stimuli are essential for the reproduction of the acquired habit.

[The use of dissociated learning in the study of the mechanisms of memory].

The review is dedicated to description of the phenomenon of dissociated learning. The distinct criteria which discriminate this phenomenon from those similar in appearance are presented. The experimental procedure is described: habituation of an animal, a device for dissociated learning, and the mode of determination of the necessary dose of a drug and injection time.

Studies of the role of the brain cholinergic system in the mechanisms of dissociative learning.

Rats were trained to make conditioned food reflex excursions in two states: in normal conditions and on a background of treatment with pharmacological agents producing dissociative states. A number of cholinergic substances were completely interchangeable in dissociative learning; anticholinergic compounds efficiently neutralized the ability of cholinergic substances to produce dissociative states; muscarinic cholinoreceptors played the leading role in production of the dissociative state.

[The role of the cholinergic system of the brain in the mechanisms of dissociated learning].

The mechanisms of dissociated learning in rats were studied with application on conditioning technique and pharmacological analysis of memory. Anticholinesterase drugs were shown to be interchangeable in inducing dissociated states in learning. Anticholinergic substances completely neutralized the ability of cholinergic drugs that create dissociated states.

[Ability of reversible cholinesterase inhibitors to support dissociative learning].

In the experiments on rats performed to study dissociated learning it was found that reversible inhibitors of cholinesterase are interchangeable. It was shown that neutralization of the behavioral effect of cholinesterase inhibitors may be induced most successfully by combined administration of M- and N-cholinergic blocking agents.

[Development of a dissociated state in the rat after administration of carbacholine into the hippocampus].

Food-procuring conditioned reaction was elaborated in rats. A single injection of carbacholine into the dorsal area of the hippocampus elicited prolonged (for several days) stable amnesia, during which elaboration of a second habit in the same animals proved possible. After cessation of the agent action, the initially elaborated conditioned reaction recurred.

[Role of the cholinergic and monoaminergic systems of the brain in dissociated learning].

Rats placed in an experimental chamber, were trained to perform two dissociated reactions; the one--in a normal state, the other--after administration of physostigmine. Then the animals were divided into 10 groups and in each group the performance of the elaborated conditioned reflexes was tested after administration of the substances influencing cholinergic and monoaminergic brain systems. It is shown that the dissociation state after physostigmine administration is due to the influence of this substance on the cholinergic brain system.

[The effect of iproniazid on biogenic amine levels, elaboration and reproduction of alimentary conditioned reflexes].

A study of the action of iproniaside on alimentary conditioning has shown that even its small doses (25 mg/kg) disturb the formation of the conditioned reaction, while large doses (200-250 mg/kg) do not disturb the reproduction of the conditioned reaction elaborated and stabilized before the administration of the drug. Hence, dissociated learning with the use of iproniaside is impossible. The applied doses of iproniaside result in an increased level of biogenic amines in the dopaminergic nigro-neostriate and reticulo-septal brain systems.