Function of the nervous system and some key concepts of neurobiology
You may know that the nervous system consists of nerve cells (neurons) within which the signal is propagated electrically - by excitation and depolarization of the neuronal cell membrane. Between each neuron, information is propagated chemically - using molecules of chemicals called neurotransmitters, or neurotransmitters. Maybe you know that a typical neuron has electrical supply leads called dendrites, a body that integrates dendritic information and a single cable called the axon. The neurons are linked together by synapses - the clones in which they touch the axon of one neuron with the dendrite of another neuron. It is the synapse that lets the signal from the axon of one neuron (called presynaptic neuron) pass into another neuron (called the postsynaptic neuron). This is done by releasing a neurotransmitter from the axon membrane of the presynaptic neuron (presynaptic membranes), which acts on the membrane of postsynaptic dendritic membrane (postsynaptic membrane). This is so that the neurotransmitter released from the presynaptic membrane is distinguished by special protein molecules in the postsynaptic membrane, called the nerve receptors. When the receptors detect a neurotransmitter, it causes the excitation of dendrite and thus the entire postsynaptic neuron. The electrical excitation of the presynaptic neuron through the synapse through the chemical neurotransmitter goes to the postsynaptic neuron. This principle works by the brain and the entire nervous system.
Classical neurotransmitters commonly found in the brain include glutamate, gamma-aminobutyric acid (GABA), glycine, acetylcholine, serotonin, dopamine and others. Each of these molecules has a specific receptor that recognizes it on the postsynaptic membrane. We say that the neurotransmitter, along with its receptor, forms the receptor system. The receptor system also includes a cascade of proteins serving the path of release of the neurotransmitter from the presynaptic membrane and the postsynaptic membrane excitation pathway after the neurotransmitter is detected by the receptor. The names of the receptor systems are derived from their neurotransmitters:
- glutamate => glutaminergic receptor system
- GABA => GABAergic receptor system
- acetylcholine => cholinergic receptor system
- serotonin => serotonergic receptor system
- dopamine => dopaminergic receptor system, etc.
Agonists and antagonists
In addition to the neurotransmitters themselves that naturally occur in receptor systems, there are many chemicals that interfere with the functioning of receptor systems. Substances that activate the receptors of the system are called agonists. Substances that inhibit receptors are called antagonists. The most typical natural agonist of a given receptor system is, of course, the neurotransmitter itself. The agonists and antagonists differ in their potency on their receptor system. Strong agonists and antagonists find many nerve poisons and drugs . For example, the alcohol is a GABA receptor agonist, and when we eat in a pub under the picture, it's because the ingested alcohol imitates the effect of γ-aminobutyric acid on its receptor, causing all well-known symptoms. When another sect in the metric wears with sarine again, it is because it acts as a cholinergic system antagonist - killing by blocking the transmission of acetylcholine signal from motor neurons axons to cholinergic receptors in the muscles. Receptor systems agonists and antagonists include thousands of different poisons and highly potent drugs.
Neuromodulator is a chemical that affects a receptor system but is not an agonist or antagonist. We can say that in neurobiology we recognize two types of effect of substances on receptor systems:
- a direct effect when the agent is an agonist or antagonist of the receptor system
- an indirect, or neuromodulatory effect, when the active substance only slightly modifies the functioning of the receptor system
The boundary between direct and neuromodulatory effects is not clearly defined. However, the neuromodulatory effect is less drastic than the direct effect.
The word neurotropic sounds professional, but it simply means that the substance somehow affects the nervous system. The term neurotropic includes both direct (agonist / antagonist) and neuromodulatory effects. A special type of neurotropic effect is a nootropic effect. Nootropics are defined as substances that increase intelligence and improve the functioning of the nervous system. Since ginseng and other adaptogens have been described as such, I wrote a special page about the nootropic effect of adaptogens .
Neurotropic effects of adaptogens
The definition of adaptogen requires that it does not interfere with the normal functioning of the organism more than is necessary to increase non-specific resistance, sic. It also follows from this definition that adaptogens must not be poisonous in a relatively high dose. Adaptogens therefore largely lack the drastic direct effects of strong agonists and antagonists of the nerve receptor systems. This does not mean that the adaptogens are ineffective: their effect on the brain and the nervous system is mainly neuromodulatory.
Additionally, the adaptogen has historically been linked to the concept of stress since its inception. The science of adaptogens was, at the time, considered to be the cutting-edge discipline of theoretical medicine , which Brechman followed up on the discovery of the Generalized Adaptation Syndrome (GAS) at that time . Because of the continuity of stress with the GAS and the hypothalamic-pituitary axis, scientists tend to label adaptive plants as stimulants for their hypothalamic-pituitary axis. Discussion of the mechanisms of this effect is therefore of great importance for adaptogens.
In terms of mechanism, adapters are particularly important for the neurosteroidal effects of their triterpenoid saponins. The concept of neurosteroids was introduced by the French physiologist Etienne Baulieu in the 1980s, who noticed that triterpenoids have neuromodulatory abilities. Due to their amphoteric character, saponins of ginseng and other adapogenics have the ability to bind to the cell membrane and nonpolar pockets of cellular receptors and other proteins. For the same reason, these saponins also have the ability to penetrate the cell membrane into the nucleus and act directly on gene expression. These adaptive saponins can be seen as neuromodulators by the character of the body close to their own hormones and neurosteroids. For the same reason, the effects of adaptogens are generally long-lasting, ie they require long-term use for their realization.
Effects of adaptogens on selected receptor systems
The non-modulatory effects of genuine ginseng saponins have been the subject of intensive research since the mid-20th century. The gypsy gypsies found out in the 1970s that they contain various components, some of which cause CNS activation, others are reassuring ( Saito1977epg ). Soon the first specific neuromodulatory panaxosides, ginsenoside Rb 1 and Rg 1 ( Tsang1985gsi , Benishin 1992 ) were identified. Since then, research into the neurosteroidal and neuromodulatory effects of individual panaxosides and other adaptive saponins has begun on various CNS receptor systems:
Other neurotrophic effects
In this section I mention the effects of adaptogens on the brain and the nervous system that did not come under the above-mentioned receptor systems. These are effects on other neuronal molecules and more general effects on the CNS. First of all, I mention the ginseng right, which was the most researched:
- Protective and regenerative effect - Ginseng saponins improve nerve fiber growth ( Takemoto1984png ) and protect brain cells from death in brain ischemia ( Wen1996grp ), chemical damage ( eg alcohol ), psychological stress and other stressful factors. The carrier of this effect is gssd. Rg 1 ( Wen1996grp , Lim1997pih ), which also counteracted the aging of cortical neurons ( Li1997eag , Jiang1996mag , Liu1995egr ) and cells in general ( Choo2003aag ).
- Effect on GABA Receptors - γ-aminobutyric acid receptors (GABA) are the most abundant receptors in the human brain. Neurosteroidal effects on GABA A and GABA B have ginsenosides Rb1, Rb2 , Rc , Re , Rf and Rg1 ( Kimura1994igw ). The stabilizing effect on the GABA system explains in part the adaptogenic anti-stress effect of ginseng ( Bhattcharya1999epg , Yuan1998mag ).
- Examples of other effects - Ginsenoside 20 (S) -Rg 3 inhibits P / Q Ca 2+ channels, Kv 1.4 K + channels and Na + IIA rat brain channels with an IC50 of tens of μM ( Jeong2004sgr ). According to Jiang1996mag and Liu1995egr , gssd. Rb 1 and Rg 1 increase Na / K-pump activity. According to the Cao1990ieg ginsenoside Rb 1 Na / K-pump, it inhibits with an IC50 of 6.3 μM. Ginseng has direct effects against pain perception (and also indirect pain-relieving effects by inhibiting inflammation ). Ginseng positively affects sleep - for example panaxosid majonoside-R 2 in stressed animals restores sleeping capacity ( Huong1998aem ). Positive effect on sleep is also reported in animal studies Lee1990cip and in the Han2013erg clinical study. At the same time, however, ginseng makes it easier to suppress sleep, so " insomnia " is the most common complaint when using ginseng. Ginseng stabilizes the activity of neurons and makes it easier to overcome withdrawal symptoms when consuming drugs .
Other plants and fungi
In addition to the model ginseng right adaptogene, American ginseng is considered to be typically neurotrophic in the genus Panax , while ginseng ( P. pseudoginseng ) or ginseng notoginseng ( P. notoginseng ) are traditionally used to modify metabolism.
In eleuterokok, the situation is unclear, whereas the use of Rhodiola rosea and Candida somnifera in the role of neuromodulatory adaptogen is supported in literature. The stairway affects serotonin and other neurotransmitters and has the potential to quit drug addiction ( Mannucci2012sir ). There are also indications that Rhodiola has the ability to induce regeneration of CNS neurons ( Chen2009err ).
A modulation effect on serotonin receptors, GABA receptors and central acetylcholine receptors ( Hsieh2001aew ) has been shown in Schisanra chinensis ( Schisanra chinensis ) and are signs of nootropic effect ( Pan2002spa , Egashira2008srm ).
It can be assumed that pancreatic gynostema ( Gynostemma pentaphyllum ) will also be neurotrophic.
Neurotropic adaptogens also include caterpillars ( Cordyceps spp.) , Peruvian cress ( Lepidium meyenii ), mistakenly referred to as Peruvian ginseng , Ginkgo biloba, and others, which I do not want to mention in part (this is long enough) , and partly unknown to science at all - that's why ethnobotanics are studying systems of native traditional medicine .