actually Quote:
From Watson SJ. Hallucinogens and other psychotomimetics: biological mechanisms.
In: Barchas JD, Berger PA, Cioranello RD, Elliot GR (eds.). Psychopharmacology from theory to practice.
Oxford: Oxford University Press, 1977.
"The current thesis of the effect of indole hallucinogens on 5-hydroxytrypamine might be stated as follows: LSD acts to preferentially inhibit serotonergic cell firing and seems to spare postsynaptic serotnergic receptors. This preference is shared by other simillar hallucinogens but in a limited fashion. Nonhallucinogenic analogs of LSD show no preference. These results suggest that there are two different steric conformation of serotonergic receptors, one of which has higher affinity for LSD than the other. In general, 5-ht is an inhibitory transmitter; thus, when its activity is decreased, the next neuron in the chain is freed from inhibition and becomes more active. Since serotnergic systems appear to be intimately involved int eh control of sensation, sleep, attention, and mood, it may be possible to explain the actions of LSD and other hallucinogens by their disinhibition of these critical systems.
There is also evidence for interaction with dopaminergic systems.
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LSD acts as a 5HT autoreceptor agonist in the raphe nucleus. These autoreceptors are typically considered to be 5HT1As. It also acts as a 5HT2 agonist, which is thought to be the main site of hallucinogenic activity. It's probably best called a a mixed 5HT2/5HT1 receptor partial agonist.
I don't know of its effects on dopamine. Wouldn't be surprised if it has 'em; the systems aren't really functionally separable. The DA effects wouldn't be necessary for hallucinogenic activity, I'd bet.
and
Quote:
It is believed that psilocybin, LSD, and DMT work by mimicking the neurotransmitter serotonin (5-HT), one of the most important and widespread of the brain's synaptic neurochemical messengers. The mimicking occurs because LSD, and particularly psilocybin, possess an almost identical molecular structure to serotonin i.e. their shape is so similar that they are able to 'fool' and infiltrate parts of the brain which process information using serotonergic synapses.
Serotonin is employed in a number of brain structures which seem to control functions like sleep, mood, and general arousal. One of these structures is the raphe system at the base of the brain, whose serotonergic neuronal axons project to all other major areas of the brain, notably the limbic system (which controls emotional responses) and areas of the visual system.
According to noted neuroscientist G.K.Aghajanian, the serotonin-using raphe system has a homeostatic function in which two primary effects emerge. Firstly, in the waking state the system acts to enhance the activity of motor neurons which govern the control of muscular movement. Secondly, and more significantly, during the waking state this same serotonergic system acts to suppress sensory systems, which are those systems relaying information about the external world. This second effect, according to Aghajanian, serves to "screen out distracting sensory cues."
Furthermore, it has been speculated that this homeostatic 'screening out' function maintains a kind of 'balance' of consciousness in which we perceive reality in a 'steady' way, almost as if the serotonergic raphe system were a balancing stick enabling us to walk the 'tightrope' of normal perceptual awareness. If this serotonergic homeostatic balancing system is interfered with, then the perception of reality will be correspondingly altered, so much so that we may plunge off the tightrope into new dimensions of perceived reality. Chemically dismantling the raphe system's screening effect would therefore admit the entry of latent information into consciousness. Is this how agents like psilocybin work?
Most of the detailed physiological experimentation that was carried out with psychedelics in the 60's concentrated on LSD and psilocybin and used rat brains, cat brains, and isolated rat neurons. Perhaps the most important finding was indeed that LSD and psilocybin depress the action of serotonin neurons in precisely the raphe system (a neuronal system shared by rats, cats and humans). The usual activity of the particular serotonergic neurons which psilocybin and LSD depress is inhibitory which means that their normal firing serves to dampen or suppress activity in the those other parts of the brain with which they synapse. Thus it was believed that psilocybin and LSD's dampening effect on serotonergic neurons facilitated an increase in neuronal firing in those areas of the brain in contact with the raphe system (like the aforementioned visual and limbic/emotion systems). It was this effect, this enhancement of neuronal activation, that was believed to correlate with the entheogenic experience itself.
It seemed like a nice neat theory. However, things are never that simple when it comes to the actions of psychedelics. For the above scenario does not take into account the more recently discovered neuropharmacological action of mescaline, another classic entheogen. With not a little theoretical irritation we find that, like psilocybin, mescaline induces the full spectrum of visionary phenomenology but is not known to significantly effect the raphe system. Which means that our raphe theory is not the whole story. Just when it was all looking so clear....
Research over the last decade has revealed that there are distinct kinds of serotonin receptors, or serotonin binding sites, within the brain. In other words, neurons which are modulated by the release of serotonin from other neurons with which they synapse, are not tied down to just one kind of serotonin receptor. In typical fashion, Nature has made things more complex and intriguing than that. In fact, there appear to be many different kinds of serotonin receptor (called sub-type receptors) and it is believed that different psychedelic drugs have differential effects upon these receptors. One particular serotonin receptor though - the so-called 5-HT2 type - appears to represent a common site of action of both psilocybin and mescaline.
5-HT2 receptors are found throughout the cortex and also in abundance in the brain system known as the locus coeruleus which, like the raphe, is situated at the base of the brain. The locus coeruleus processes so many sensory inputs (a flow of incoming data if you like) that it is considered to function as a 'novelty detector' and is able to influence one's state of arousal. By monitoring the constant surge of 'electrochemical traffic' passing through it, the locus coeruleus is able to detect changes in the flow of data should a change occur and thus alert other parts of the brain. According to our expert G.K.Aghajanian, both psilocybin and mescaline bind to these 5-HT2 sites in the locus coeruleus and thus alter the functioning of this system, ultimately raising levels of alertness and arousal. In other words, it once again seems that entheogens function by making more information available to the experiencer.
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i dont cultivate...i just post pictures, spread knowledge, and give advice
my brain's illegal because it contains DMT in the pineal gland, and so does your brain and everyone elses
the name's GestaltAssault not Get Us A Slut
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