Plants Affecting Serotoninergic Neurotransmission

5 - 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.

y ^^ Mesembrine

y ^^ Mesembrine

Sertraline (Zoloft®)

5-Hydroxytryptaminergic (5HT1A) receptors mediate in the CNS the autonomic control of hypothermia, hyperphagia, analgesia, blood pressure, venereal disease, anxiety, and several behavioral paradigms. It has been hypothesized that the anxiolytic property of buspirone is the result of a blockade of 5HT1A receptors. Methysergide, a partial 5HT1 agonist, and sumatriptan, a 5HT1D agonist, are drugs used to assuage headache.

Plants affecting the serotoninergic neurotransmission are therefore interesting because of their potentials for the treatment of depression, which is the eighth leading cause of death in the United States. It is generally agreed that there is a correlation between diminished serotonin neurotransmission and episodes of major depression, and a number or inhibitors of serotonin-uptake inhibitors are available on the market, such as sertraline (Zoloft®).

This type of action is found in kanna, or Sceletium expansum and Sceletium tortuosum (Aizoaceae), which have been used by South African shamans from prehistoric times to "enhance animal spirits, sparkle the eyes, and to stimulate gaiety." The active constituent of kanna is a serotonin-like alkaloid called mesembrine, which is a potent serotonin re-uptake inhibitor—hence, some potential for the treatment of anxiety and depression; however, careful clinical trials must be performed.

When looking for plants affecting serotoninergic neurotransmission, one might look into species that produce indole alkaloids, such alkaloids beingknown to impart to the plant's hallucinogenic properties.

Such alkaloids can be found particularly in the Myristicaceae, Malpighiaceae, Rutaceae, Apocynaceae, Rubiaceae, Loganiaceae, and Convolvulaceae. Such compounds are also found in mushrooms from the genera Conocybe, Panaeolus, Psilocybe, and Stropharia (Agaricaceae), which where used by the Aztecs of pre-Columbian America for their psilocin.

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