Serotoninergic System

Anxiolytics are compounds that act primarily to refleve the symptoms of anxiety although such agents can also be used as anticonvulsants, sedatives, hypnotics, and anesthetic agents (see Anesthetics). The principal class of anxiolytics, the BZs, shows dependence HabiUty (5) whereas newer agents such as buspkone [36505-84-7] and ritanserine [8705-43-2] produce antianxiety effects via central serotoninergic systems (6). 

Dopamine System Histaminergic system Muscarinic Receptors Serotoninergic System Tachykinins and their Receptors... 

Serotoninergic System GABAergic System Ionotropic Glutamate Receptors Glycine Receptors... 

Serotoninergic System. Figure 1 Graphical representation of the current classification of 5-hydroxytryptamine (5-HT) receptors. Receptor subtypes represented by shaded boxes and lowercase designate receptors that have not been demonstrated to definitively function in native systems. Abbreviations 3-5r cyclic adenosine monophosphate (cAMP) phospholipase C (PLC) negative (-ve) positive (+ve)... 

Hydroxy tryptamine, or serotonin, is a neurotransmitter in the central nervous system (CNS). The nerve-cell bodies of the major serotoninergic neurones are in the midline raphe nuclei of the rostral pons, and ascending fibers innervate the basal ganglia, hypothalamus, thalamus, hippocampus, limbic forebrain, and areas of the cerebral cortex. The serotoninergic system plays an important role in the control of mood and behavior, motor activity, hunger, thermoregulation, sleep, certain hallucinatory states, and some neuro-endocrine mechanisms. 

In regard to the experimental evidence available, a substantial number of reports on the chemical constituents of the plant are available, but much less work has been done with the pharmacological properties. Kasture et al., however, made the important observation that a triterpene isolated from R. cordifolia induces anxiety in rodents, an effect accompanied with an increase in serotonin contents in the brain (30). An interesting development from that observation would be to explore further the molecular-pharmacological pathway and the effect of this agent on the serotoninergic system because terpenes, compared with indole alkaloids, are seldom reported for serotoninergic activities. 

Studies of sudden death in novice as well as experienced drug abusers found that cocaine causes vasoconstriction of the coronary arteries which seems to result from an enhancement of Ca2+ influx across myocardial membranes. However, remember that this class of drug affects other neurotransmitter systems. Cocaine inhbiits reuptake of NE and 5-HT as well as binds to the DA transporter. It increases catecholamine receptor sensitivity but does not seem to directly influence enkephalinergic receptors. In addition it also affects neurotransmission the H, Ach and phenylethylamine pathways. Activation of DA, NE or 5-HT neurons independently does not produce the euphoria associated with cocaine misuse. Euphoria seems to be related to simultaneous inteeraction between catecholamine and serotoninergic systems. 

Synergy within the serotoninergic system. Boosting serotonin neurotransmission has proved to be useful not only in treatment-resistant depression, but for treatment resistance within the whole family of serotonin spectrum disorders, such as obsessive-compulsive disorder, panic disorder, social phobia, posttraumatic stress disorder, and bulimia. 

Volicer, L., Langlais, P. J., Matson, W. R., Mark, K. A., and Gamache, P. H. (1985). Serotoninergic system in dementia of the Alzheimer type. Abnormal forms of 5-hydroxy-tryptophan and serotonin in cerebrospinal fluid. Arch. Neurol. 42 1158-1161. 

A few studies describe interactions between the dopaminergic and the serotoninergic systems in the substantia nigra, thereby suggesting a role for nigral dopamine receptors. 

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