Involvement of transmitter systems in neuropsychiatric diseases

Normal function of the central nervous system (CNS) requires intact morphology as well as neurotransmission. Diseases of the CNS can become manifest as a sensorimotor deficit or psychic alteration, or both. When observing neuropsychiatric diseases, interaction of different transmitter systems is obvious. Thus, an increase or a decrease of transmitter systems affect each other. Mechanisms of compensation can also lead to alterations in transmitter systems not involved in the pathological process. Parkinson's disease, hyperkinetic movement disorders like ballism and Huntington's chorea, epilepsy and anxiety will be used in this paper as examples of the synergistic action of dopaminergic, peptidergic, glutamatergic, GABAergic and cholinergic neurotransmission. With our knowledge of the functional balance of transmitter systems in the CNS, various pharmacological strategies have been available to intervene in the pathophysiological process. The excitatory or inhibitory quality of the transmitter systems must be considered if such strategies are to be employed. On the other hand, a functional balance between two or more transmitter systems may cause a contrary therapeutic intervention on the opposite side of the balance.