EARLY POSTNATAL DYSFUNCTIONING OF THE BRAIN MUSCARINIC CHOLINERGIC SYSTEM AND THE DISORDERS OF FEAR-MOTIVATED LEARNING AND MEMORY.

The aim of the study was to investigate the early postnatal dysfunctioning of the brain muscarinic cholinergic system as a major factor in the development of cognitive disorders similar with somewhat is noted in animal models of depression and in patients with Major Depressive Disease. The present study examined the processes of learning and long-term retention of information obtained in the two important tasks of non-declarative memory - active avoidance, motivated by foot shock-induced fear, and the elevated plus-maze, based on the natural fear.Experiments were carried out on male white wild rats (n=60). Four groups of animals (15 rats in each) were used with special procedures for each one. Early postnatal dysfunctioning of the brain muscarinic cholinergic system was produced by the new method worked out by Nachkebia and co-authors. Two-way shuttle-box and elevated plus maze devices were used for the investigation of fear-motivated non-declarative memory and anxiety.The lasting effects of early postnatal dysfunctioning of the brain muscarinic cholinergic system on non-declarative learning and memory and anxiety were studied for the first time in the present work. Following new facts were obtained: 1) This procedure produces in adult age initial impairment of learning in a non-declarative memory test that is based on the enhancement of the level of anxiety in both active avoidance and elevated plus maze tests; 2) Dysfunctioning of the brain muscarinic cholinergic system, in the period of early ontogenesis, does not change in adult animals the consolidation and long-term retention of information obtained in the two important tasks of non-declarative memory, active avoidance, motivated by foot shock-induced fear, and the elevated plus-maze, based on the natural fear; 3) Intraperitoneal injection of Scope in adult animals, subjected during early ontogenesis to the dysfunctioning of the muscarinic cholinergic system, reduce the level of anxiety and facilitates by this way learning and memory of natural fear-motivated non-declarative test. Early postnatal dysfunctioning of the brain muscarinic cholinergic system enhances the level of anxiety in adult age and complicates acquisition of information in fear-motivated non-declarative learning and memory tests, but does not change its consolidation and long-term retention.