Category: N
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Noradrenergic and specific serotonergic antidepressants (NaSSAs)
A class of atypical antidepressants that exert their effects by antagonizing presynaptic alpha2 receptors of both noradrenergic and serotonergic neurons, resulting in enhanced neurotransmission of norepinephrine and serotonin. NaSSAs are used primarily for the treatment of depression and anxiety disorders. An example of an NaSSA is mirtazapine (remeron).
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Noradrenergic
Referring to the neurotransmitter norepinephrine (noradrenaline).
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Noonan syndrome
A congenital (present at birth) genetic condition whose principal features include congenital heart defect, short stature, indentation of the chest, impaired blood clotting, and a characteristic configuration of facial features. Cognitive deficits, social problems, attention deficits, and anxiety are also present. Noonan syndrome is a rare genetic disorder that causes a wide range of clinical…
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NMDA receptor antagonists
A class of drugs that inhibit the action of the nmda (n-methyl-d-aspartic acid) receptor. Examples include ketamine and phencyclidine (PCP) (often used illicitly for recreational purposes), memantine (used to treat the symptoms of alzheimer’s disease), and amantadine (used to treat side effects of conventional antipsychotic medications, especially dystonia and akathisia).
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N-methyl-D-aspartic acid
A compound that acts as a specific agonist at the NMDA receptor, mimicking the effects of the neurotransmitter glutamate.
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Nitrous oxide
Laughing gas; it rapidly produces intoxication, with light-headedness and a floating sensation. Symptoms disappear within minutes after discontinuation of the substance; however, temporary but clinically relevant confusion and reversible paranoid states have followed regular use. An anesthetic gas sometimes used recreationally as an inhalant. A colourless gas with a sweet smell, used in combination with…
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Nitrite inhalants
Inhaled substances (street name: “poppers”), including amyl, butyl, and isobutyl nitrite, that produce an intoxication characterized by a feeling of fullness in the head, mild euphoria, a change in the perception of time, relaxation of smooth muscles, and possibly an increase in sexual feelings. The nitrites may produce psychological dependence and may impair immune functioning,…
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Nihilistic delusion
The delusion of nonexistence of the self or part of the self, or of some object in external reality. A fixed belief that everything is unreal, that nothing really exists. A delusion that everything has ceased to exist.
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Nightmare disorder
Dream anxiety disorder; a parasomnia consisting of repeated awakenings from sleep with detailed recall of extended and extremely frightening dreams, usually involving threats to survival, security, or self-esteem. On awakening from the frightening dream, the person rapidly becomes oriented and alert. This contrasts with the confusion and disorientation characteristic of sleep terror disorder and some…
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Nicotinic receptors
A subtype of cholinergic receptor specifically responsive to nicotine. Specialized cells within the central nervous system that are sensitive to the level of nicotine in body tissues. A cholinergic receptor found at the neuromuscular junction on skeletal muscle and in the autonomic ganglia, which responds to nicotine and nicotine-like drugs. A primary class of cholinergic…