The functioning of the nervous system and some key concepts of neurobiology
You may know that the nervous system consists of nerve cells (neurons), inside which the signal propagates electrically - using excitation and depolarization of the cell membrane of the neuron. Among individual neurons are then chemically spread information - using molecules called neurotransmitters, chemicals, or neurotransmitters. Perhaps you know that a typical neuron has a power cord, called dendrites, the body which integrates information supplied dendrites and one outlet cable called an axon. The neurons are interconnected synapses - connections in which the axon of a neuron touches the dendrite of another neuron. Now synapse allows the signal from the axon of a neuron (called presynaptic neuron) passed to another neuron (called postsynaptic neuron). It happens so that a membrane axon presynaptic neuron (synaptic membranes) is released neurotransmitter that acts on the membrane of the postsynaptic neuron dendrites (postsynaptic membrane). It happens so that the neurotransmitter released from presynaptic membranes is recognized by specific protein molecules in the postsynaptic membrane, called nerve receptors. When the receptors detect neurotransmitter causes excitation of a dendrite and thus the entire postsynaptic neuron. The electrical excitation of presynaptic neuron across the synapse and using a chemical neurotransmitter passes on the postsynaptic neuron. On this principle works the brain and the entire nervous system.
Among the classic neurotransmitters abundant in the brain glutamate, γ-aminobutyric acid (GABA), glycine, acetylcholine, serotonin, dopamine and others. Each of these molecules has a specific receptor, that it recognizes the postsynaptic membrane. We say that the neurotransmitter together with its receptor forms a receptor system. The receptor system also includes a cascade of protein serving path release of neurotransmitters from presynaptic membrane and postsynaptic membrane excitation path after detecting neurotransmitter receptor. Names 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.
Beside the neurotransmitters that are naturally present in the receptor systems, there are a large number of chemicals that the functioning of receptor systems interfere. Substances that this receptor-activated system, which are called agonists. Substances which inhibit the receptors are called antagonists. The most typical natural agonist of the receptor system is of course itself a neurotransmitter. Agonists and antagonists differ force which acts on its receptor system. Among potent agonists and antagonists we find many nerve poisons and drugs . For example, alcohol is an agonist of GABA receptors and when the pub Ozer drunk, so that by drinking alcohol mimics the effects of γ-aminobutyric acid to its receptor, thereby causing us all well-known symptoms. When we turn a sect in the subway sarin poisoning, so it's the fact that this gas acts as an antagonist to the cholinergic system - it kills by blocking acetylcholine signal transmission from the axons of motor neurons to cholinergic receptors in the muscles. The agonists and antagonists of receptor systems include thousands of different poisons and potent drugs.
Neuromodulator is a chemical which affects some receptor systems, but is an agonist or an antagonist. We can say that in neurobiology distinguish two types of effects of substances on receptor systems:
- direct effect where the substance agonist or antagonist of the receptor system
- indirect or neuromodulator effect when the active substance is only slightly modifies the functioning of the receptor system
Boundaries between direct and neuromodulatory effect is not sharply defined. But one can say that the neuromodulator effect is unlike the direct effect less drastic.
Neurotropic word sounds professional, but simply means that the substance somehow acts on the nervous system. Under the term neurotrophic include both direct (agonist / antagonist) and neuromodulation effects. A special kind of neurotrophic effect is nootropic effect. Nootropics are defined as substances that increase the intelligence and improving the functioning of the nervous system. Because ginseng and other adaptogens was described such influence, I wrote about the nootropic effect of adaptogens special page .
Neurotrophic effects of adaptogens
Definitions adaptogens requires that the interference with the normal functioning of the body more than necessary to enhance non-specific resistance, SiC. This definition also implies that adaptogens nor the relatively high dose toxic. Adaptogenům therefore mostly lacking drastic strong direct effects of agonists and antagonists of nerve receptor systems. That does not mean that they are adaptogens ineffective: their effect on the brain and nervous system is mainly neuromodulation.
Moreover adaptogen historically been associated since its inception with the concept of stress . The science of adaptogens was in its time-intentioned as the top discipline of theoretical medicine , which Brechman build on the then new discovery generalized adaptation syndrome (GAS) . Precisely because of the stress conjunction with GAS and hypothalamic-pituitary axis, scientists today have a tendency to mark an adaptogen plants encouraging its effect on the hypothalamic-pituitary axis. Discussion mechanism of this effect is therefore of great importance in adaptogens.
In terms of the mechanism are among adaptogens especially important neurosteroid effects of triterpenoid saponins. Neurosteroids concept introduced in the 80s of the 20th century French physiologist Etienne Baulieu, who noticed that the triterpenoids have the ability neuromodulation. Due to its amphoteric nature have ginseng saponins and other adaptogens ability to vmezeřit to the cell membrane and nonpolar pockets cell receptors and other proteins. For the same reason also these saponins have the ability to penetrate the cell membrane to the nucleus and act directly on gene expression. These saponins, adaptogens can be seen as the close nature of neuromodulators body's own hormones and neurosteroidům. For the same reason, the effects adaptogens generally long, i.e. requiring for their realization long term use.
Neuromodulation effects of saponin ginseng have been the subject of intense research since the mid-20th century. Japanese ginseng already in the 70s found that the various components, all of which cause the activation někeré CNS others are soothing ( Saito1977epg ). Soon identified the first concrete neuromodulation panaxosidy, ginsenoside Rb 1 and Rg 1 ( tsang1985gsi , Benishin1992agr ). Since then ran neurostoroidal research and neuromodulation effects of individual panaxosidů and other adaptogenic saponins on various receptor systems CNS:
Another neurotrophic effects
In this section, I mention adaptogens effects on the brain and nervous system that do not fit under the aforementioned receptor systems. There are the effects on other molecules neurons and also more general effects on the CNS. In the first place again I mention the true ginseng, which has done the most research:
- The protective and regenerative effect - Ginseng saponins enhance growth of nerve fibers ( Takemoto1984png ) and protect brain cells against cell death in cerebral ischemia ( Wen1996grp ), chemical damage ( e.g. alcohol ), mental stress and other stress factors. The bearer of this effect is gssd. Rg 1 ( Wen1996grp , Lim1997pih ), who also worked against aging cortical neurons ( Li1997eag , Jiang1996mag , Liu1995egr ) and cells in general ( Choo2003aag ).
- The effect on GABA receptors - receptors γ-aminobutyric acid (GABA) are the most abundant receptors in the human brain. Neurostoroidal effect on GABA A and GABA B have ginsenosides Rb 1 , Rb 2 , Rc , Re , Rf and Rg 1 ( Kimura1994igw ). Stabilizing effect on GABA system in part explains adaptogenic anti-stress effect of ginseng ( Bhattcharya1999epg , Yuan1998mag ).
- Examples of other effects - Ginsenoside 20 (S) -rg 3 inhibits P / Q Ca2 + channels Kv 1.4 K + channels and Na + IIA channels in rat brain with an IC 50 of tens um ( Jeong2004sgr ). According Jiang1996mag and Liu1995egr , gssd. Rb 1 and Rg 1 increased the activity of Na / K-pump. According Cao1990ieg ginsenoside Rb 1 Na / K-pump conversely inhibits with an IC50 of 6.3μM. Ginseng has direct effects against the perception of pain (and also the indirect effects of painkillers dampening the inflammatory response ). Ginseng positively affects sleep - for example panaxosid Majonosid-R 2 in stressed animals restores the ability to fall asleep ( Huong1998aem ). The positive effect on sleep states and animal studies Lee1990cip and clinical studies Han2013erg . But it also makes ginseng option will suppress sleep, so " insomnia " is finally in use ginseng common complaint. Ginseng stabilizes neuronal activity and facilitates overcoming withdrawal symptoms from addictive substances .
Other plants and fungi
In addition to the model adaptogen ginseng for neurotropic typically in the genus Panax also considered as American ginseng , while ginseng false (P. pseudoginsng) or ginseng notoginseng (P. notoginseng) are traditionally used rather to regulate metabolism.
For eleutherocok situation is unclear, while the use of Rhodiola rosea (Rhodiola rosea) and hailing snodárné (Withania somnifera) in the role of neuromodulation adaptogen has support in the literature. Rhodiola affects levels of serotonin and other neurotransmitters, and has potential withdrawal from drug addiction ( Mannucci2012sir ). There are also indications that Rhodiola has the ability to induce the regeneration of CNS neurons ( Chen2009err ).
For Schizandra chinensis (Schisanra chinensis) showed a modulatory effect on the serotonin receptors, GABA receptors, and central acetylcholine receptors ( Hsieh2001aew ) and are indications nootropického effect ( Pan2002spa , Egashira2008srm ).
It can be assumed that neurotropic will panaxosidy containing Jiaogulan (Gynostemma pentaphyllum) .
Among neurotropic adaptogens include Cordyceps sinensis (Cordyceps spp.) , Watercress Peruvian (Lepidium meyenii) incorrectly referred to as Peruvian ginseng , ginkgo (Ginkgo biloba) and others that part I do not want to mention (already this site long enough), partly know and partly science are not known at all - that's why ethnobotanicals studying systems of indigenous traditional medicine .