Serotonin and Dopamine

mondor mondor at micronet.fr
Tue Jul 9 00:46:00 EST 1996


Claude de Contrecoeur wrote:
> 
> Dopamine et Sérotonine
> 
> Le Rôle de la Dopamine et de la Sérotonine dans le Système Nerveux Central(S.N.C)
> 
> The Role of Dopamine and Serotonin in the Central Nervous System(C.N.S)
> --------------------------------------------------------------------------------------
> -----------------------
> Serotonin and dopamine play,normally,opposite roles in the CNS:
> Serotonin decreases behaviours while dopamine stimulates behaviours.So serotonin
> enhances INACTIVITY while dopamine stimulates ACTION.
> According to Dr.Henri Laborit(the father of chlorpromazine)there is a system of
> Action, in the CNS, linked to a system of inhibition.
> There is a balance of actions between dopamine and serotonin.This is called
> the Dopamine/serotonin balance.There is also a balance of actions between
> serotonin itself.For instance,most serotonin actions decrease dopaminergic
> activity while,sometimes,serotonin can,paradoxically,enhance dopamine
> influence through 5-HT2A receptors for example.
> The balance of inhibition and activation of dopamine by serotonin is called
> the Serotonin/Serotonin balance.
> 
> Effects of Serotonin on Behaviour
> -----------------------------------------------
> Serotonin controls the quantity of information flow from memory to
> consciousness.Increasing serotoninergic activity,for instance through the
> specific serotonin reuptake blockers,will decrease the quantity of
> information flow from memory to consciousness while decreasing serotoniner-
> gic activity through hallucinogens(with the notable exception of 5-HT2A
> receptors)will increase information flow from memory to consciousnness.Under a
> serotonin reuptake blocker consciousness is nearly devoid of thoughts,at certain
> optimum doses,while under hallucinogens the opposite happens:consciousness is full of
> thoughts.The same holds true with cannabinoids.
> Increase in serotonin leads to THYMOANESTHESY which means that serotonin
> anesthesises emotions.
> Decrease in serotonin(for example through MDMA,MDA,etc)leads to stimulation
> of sociability and mood,aggressivity and sexuality,etc,probably by augmenting
> dopaminergic activity normally blocked by serotonin(except 5-HT2A receptors).However
> MDMA and MDA lead only to stimulation of sociability, probably at a site or sites
> modulated by the Median Raphé Nucleus.
> Here are some effects of serotonin, as demonstrated through zimelidine and
> fluvoxamine:
> I.Decrease in informational flow from memory to consciousness:the quantity
> of thoughts per unit of time,under zimelidine or fluvoxamine,reaching
> consciousness is diminished as to base-line levels.
> 2.Motivations are decreased.
> 3.Emotions are anesthesised
> 4.Sexual desire is decreased or suppressed
> 5.Sleep or quasi-sleep is increased
> 6.Aggression is reduced.
> 7.Locomotion is diminished
> 8.Because of (1)obssesive thoughts or suicidal thoughts,etc,are reduced
> 9.Under fluvoxamine suicidal ideation can be reversed quite fast but not as
> spectacularly as with Gamma-hydroxybutyrate.
> 
> Contrary to typical serotoninergic reuptake blockers which induce somnolence
> fluoxetine is atypical because it induces insomnia.It can also induce
> headaches which are reversed by fluvoxamine.Insomnia is also reversed
> through fluvoxamine.As also fluoxetine(Prozac)is SUBHALLUCINOGENIC one
> concludes that fluoxetine has a differential tendency to indirectly
> stimulate 5-HT2A receptors,thus activating dopaminergic activity.
> Activation of dopamine neurotransmission leads to insomnia.
> 
> Effects of Dopamine on Behaviour
> -----------------------------------------------
> The effects of dopamine on behaviour can be evaluated with the dopamine
> reuptake blockers amineptine and nomifensine(nomifensine has also a
> noradrenergic component).
> Stimulation of dopamine neurotransmission can induce the following effects:
> I.Mental and motor activation.
> 2.Stimulation of mood WITHOUT concomittant "euphoria".
> 3.Amineptine can induce a potentiation of benzodiazepines induced
> anxiolysis.
> 4.Some authors say that amineptine can alleviate some schizophrenic sympt-
> oms,which is consistent with the hypothesis of hypofrontality linked
> to decrease in dopamine neurotransmission.
> 5.Dopamine seems to be an UBIQUITOUS METABOLIC ACTIVATOR.It thus activates
> neuronal systems while serotonin,normally,seems to deactivate neuronal
> systems.So the purpose of dopamine,PER SE,in the CNS seems only to modulate metabolic
> activity of other systems.
> In this sense,dopamine IS NOT directly linked to pleasurable experiences.It only
> serves to activate post-dopaminergic systems involved in these behaviours...
> 6.Dopamine stimulates motivations and lifts undecisiveness.Undecisiveness gives rise
> to self-confidence.If dopamine is overactivated then self-confidence increases to the
> point of being delusional!
> 7.Activation of some dopamine autoreceptors seems to decrease activity.
> So there should also exist a Dopamine/Dopamine balance.
> 
> La Sérotonine et la Dopamine dans les Etats de Conscience
> 
> Serotonin and Dopamine in States of Consciousness
> ---------------------------------------------------------------------------
> 
> A.Depression
> --------------------
> Serotonin alleviates depression by reducing excessive reaction to exogenous or
> endogenous stimuli.Serotonin is an ANTI-STRESS molecule which is very effective
> leading,ultimately,to blunting of emotions such as THYMOANESTHESIA.
> Thus serotonin seems to be one of the molecule of PLACIDITY,tranquillity,peace of
> mind.Maybe adepts of Zen could stimulate their serotoninergic system in order to
> attain serenity.
> 
> Dopamine alleviates depression by STIMULATING ACTION and lifting undecision.Dopamine
> activates blood-flow which may be an important factor in its anti-depressive action.
> Depression is ALSO lifted in the oneiric state,while metabolic activity in the CNS is
> very high.
> Depressed people are NOT depressed anymore in the dream state but become,all of a
> sudden,depressed again when they go out of the dream state.This can be explained in
> term of metabolism and in the way memory is structured.
> But,apart from myself,nobody else has studied this very interesting problem...
> 
> B.Schizophrenia
> ------------------------
> Serotonin seems to play a role in the blunting of emotions seen in schizoprenics.
> This is why I usually refer to these symptoms as the "serotonomimetic syndrome".
> Dopamine HYPOACTIVITY in the frontal cortex is responsible for the negative symptoms
> of schizophrenia while HYPERACTIVITY elsewhere is responsible of the positive
> symptoms.
> 
> Conclusion:
> ------------------
> Dopamine and Serotonin seem to work in concert in the nervous system in order to
> MODULATE levels of activities of neuronal systems.
> In a way they are analoguous to the peripheral sympathic and parasympathic systems!


C'est bien de lire du français
http://www.micronet.fr/~mondor



More information about the Neur-sci mailing list