Abstract

INTRODUCTION

HISTAMINE AND ACh

COGNITIVE IMPLICATIONS

CONCLUSIONS

REFERENCES

Discussion
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Interactions between the cholinergic and other neurotransmitter systems may be important in learning and memory. Histamine, e. g., modulates the activity of nucleus basalis magnocellularis (NBM) cholinergic neurons, which provide cholinergic innervation to the cortex. Stimulation of H3 receptors, localized on GABAergic interneurons in the cortex, inhibits, while activation of H1 receptors, localized on cholinergic perykaria in the NBM, facilitates cortical ACh release. As a consequence of modified ACh levels, these effects may have a relevance in learning and memory, since cognitive deficits are related to reduced availability of ACh in the synaptic cleft. Indeed, H3 receptor agonists impair rat cognitive performance in object recognition and a passive avoidance response at the same doses that reduce potassium-evoked acetylcholine release from cortex. Conversely, H3 receptor antagonists show beneficial effects on cognitive processes, preventing scopolamine-induced amnesia in the same behavioural tasks Rats treated with 2-(3-(trifluoromethyl)-phenyl)histamine, an H1 agonist, perform significantly better than controls in object recognition. Thus, the dual effect of histamine on cortical cholinergic activity (excitatory at the cell bodies, and inhibitory at the terminals) may have implications for the treatment of disorders associated with impaired cortical cholinergic functions.

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Presentation Number SAblandina0227
Keywords: Acetylcholine, Histamine, cortex, microdialysis, cognition