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Short answer The mechanism of action of serotonin-specific reuptake inhibitors, a commonly-prescribed class of antidepressants, is a downregulation of 5HT1A receptors through negative feedback. This downregulation of receptors takes time. Background Serotonin-specific reuptake inhibitors (SSRIs) are a class of antidepressants commonly prescribed to treat ...


5

Short answer Withdrawal effects are generally associated with drugs that induce feelings of euphoria by stimulating the reward center of the brain, either directly (cocaine, morphine) or indirectly (alcohol, nicotine). The classic hallucinogens have little effect on the dopaminergic pathways and hence do not cause serious withdrawal effects as observed with ...


5

what does the "two photon" means? Ordinary confocal microscopy uses single photon of laser light to excite the molecule of fluorescent dye. In two photon microscopy you use two photons, with lower energy, which cannot excite the molecule of dye on their own, but their interference in a specific place leads to summation of their energies and to excitation. ...


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Cacao and products made from cacao contain a number of bioactive compounds. As far as the subjective sensation of a "buzz", there are three related alkaloids present in cacao that may account for this effect. Theobromine is present in the highest concentration, but is probably less potent of a stimulant. It's not well researched. Theophylline has a number of ...


4

Short answer First-generation anti-histamines are psychoactive, second-generation equivalents may not be*. Background According to WHO, psychoactive substances are: [...] substances that, when taken in or administered into one's system, affect mental processes, e.g. cognition or affect. This term and its equivalent, psychotropic drug, are the most ...


4

Short answer Chemical reversible shielding of the aminogroup in GABA seems to be sufficient to get it into the brain as a Trojan horse. Background Given that you ask ...how to make GABA pass the blood brain barrier? I assume that You wish to elevate GABA by exogenously administering a compound; That compound has to cross the blood-brain barrier (...


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Short answer The dopamine hypothesis includes brain regions with reduced dopamine transmission as well. The prefrontal cortex in specific has reduced dopaminergic activity and is implicated in anhedonia. It affects pleasure seeking behavior through interactions with the nucleus accumbens. Background The negative symptoms of schizophrenia are less well ...


3

Short answer Atropine inhibits an inhibitor and hence its effects are excitatory. Background According to the wiki page on muscarine M2 receptor: M2 muscarinic receptors act via a Gi type receptor, which causes a decrease in cAMP in the cell, generally leading to inhibitory-type effects. Atropine is an antimuscarinic (anticholinergic) drug....


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As Christiaan already pointed out, this depends on the pharmacokinetic and pharmacodynamic parameters. The effective drug concentration depends on the drug-receptor association constant and the drug degradation constant (for a highly simplified model). The degradation/removal depends on the abundance of the enzyme catalyzing this reaction. Ethanol is ...


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Short answer Valerian preparations contain many compounds, but it is not known which may be responsible for its sedative effects. It is likely that there is no single active compound and that valerian's effects result from multiple constituents acting independently or synergistically (source: NIH). Overall, I think it is safe to say that valerian's sedative ...


2

It seems that the reason for the different effect of Atropine and Scopolamine on the brain is related to the structural difference between them. From the chemical structures below it is evident that the two molecules are almost identical, save for an epoxide group that is found in Scopolamine but not in Atropine. According to Brody's Human Pharmacology: ...


2

Interesting notion. However, the main effects of the indoleamine-class of psychoactive compounds, including psilocybin and LSD (Shulgin, 1997), are generally ascribed to 5-HT2A receptors and the glutamatergic system (Aghajanian & Marek, 1999). The stimulant effects of the phenetylamines (PEAs) such as amphetamine and related compounds (Shulgin, 1991) ...


2

We were taught that ganglionic receptors have very high thresholds. So we need a very high concentration of the drug to produce the sympathetic effects. We even solved a hypothetical problem in class, where a patient presented with a pinpoint pupil (typical insecticide poisoning) and increased secretions but an increased heart rate (usually they present with ...


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A state of unconsciousness does not guarantee analgesia nor amnesia. Besides, a muscle relaxant is often paramount to prevent movements. The perfect general anesthetic would do all of this and have hypnotic, analgesic, amnesic and muscle relaxant properties. Such compounds do not exist, because each effect works on a different part of the brain or elsewhere. ...


1

There are probably over a hundred compounds in cacao that might possibly have effects on humans. I don't want to speculate on the ones that are not known. One that is known is theobromine. I have seen a claim that cacao does not actually have caffeine, but I haven't checked it. Cacao might not have theophylline either. The link did not work for me. no ...


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For a full understanding I refer you to the KEGG pathway map which is fairly comprehensive in showing all the metabolic processes that CAN produce Adenosine. It's a bit daunting but if you find it on the map here it is interactive and you can see the enzymes and pathways involved. If you drill down it brings you to a host of papers and references in primary ...


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You trespass upon a question as old as antiquity: what properties constitute consciousness? The best means to respond to the question concerns a metaphysical answer and an answer in modern biology We can perhaps divide consciousness into two categories: contiguous thought from past experience and identity and secondly, self-awareness. The reputed example ...


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