The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. Substantia nigra is Latin for "black substance", reflecting the fact that parts of the substantia nigra appear darker than neighboring areas due to high levels of neuromelanin in dopaminergic neurons. Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta.
The N-methyl-D-aspartatereceptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and predominantly Ca2+ ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and kainate receptors. Depending on its subunit composition, its ligands are glutamate and glycine (or D-serine). However, the binding of the ligands is typically not sufficient to open the channel as it may be blocked by Mg2+ ions which are only removed when the neuron is sufficiently depolarized. Thus, the channel acts as a "coincidence detector" and only once both of these conditions are met, the channel opens and it allows positively charged ions (cations) to flow through the cell membrane. The NMDA receptor is thought to be very important for controlling synaptic plasticity and mediating learning and memory functions.
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.
Dopaminergic pathways in the human brain are involved in both physiological and behavioral processes including movement, cognition, executive functions, reward, motivation, and neuroendocrine control. Each pathway is a set of projection neurons, consisting of individual dopaminergic neurons.
Amantadine, sold under the brand name Gocovri among others, is a medication used to treat dyskinesia associated with parkinsonism and influenza caused by type A influenzavirus, though its use for the latter is no longer recommended because of widespread drug resistance. It is also used for a variety of other uses. The drug is taken by mouth.
Memantine, sold under the brand name Axura among others, is a medication used to slow the progression of moderate-to-severe Alzheimer's disease. It is taken by mouth.
Dopaminergic means "related to dopamine", a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain.
Neuroprotection refers to the relative preservation of neuronal structure and/or function. In the case of an ongoing insult the relative preservation of neuronal integrity implies a reduction in the rate of neuronal loss over time, which can be expressed as a differential equation.
Pramipexole, sold under the brand Mirapex among others, is a medication used to treat Parkinson's disease (PD) and restless legs syndrome (RLS). In Parkinson's disease it may be used alone or together with levodopa. It is taken by mouth. Pramipexole is a dopamine agonist of the non-ergoline class.
Mesocarb is a drug that is currently being developed for Parkinson's disease.
Siramesine is a sigma receptor agonist, selective for the σ2 subtype. In animal studies, siramesine has been shown to produce anxiolytic and antidepressant effects. It was developed by the pharmaceutical company H Lundbeck for the treatment of anxiety, although development was discontinued after clinical trials showed a lack of efficacy in humans. Siramesine has been shown to produce an enhanced antidepressant effect when co-administered with NMDA antagonists. It has also been used to study the σ2 activity of cocaine, and has been shown to produce anticancer properties both in vitro and in vivo.
The sigma-2 receptor (σ2R) is a sigma receptor subtype that has attracted attention due to its involvement in diseases such as neurological diseases, neurodegenerative, neuro-ophthalmic and cancer. It is currently under investigation for its potential diagnostic and therapeutic uses.
Budipine is an antiparkinson agent marketed for the treatment of Parkinson's disease.
Ifenprodil, sold under the brand names Cerocral, Dilvax, and Vadilex, is a cerebral vasodilator that has been marketed in some countries, including in Japan, Hong Kong, and France. It is currently under development for treatment of a variety of additional indications.
The glutamate hypothesis of schizophrenia models the subset of pathologic mechanisms of schizophrenia linked to glutamatergic signaling. The hypothesis was initially based on a set of clinical, neuropathological, and, later, genetic findings pointing at a hypofunction of glutamatergic signaling via NMDA receptors. While thought to be more proximal to the root causes of schizophrenia, it does not negate the dopamine hypothesis, and the two may be ultimately brought together by circuit-based models. The development of the hypothesis allowed for the integration of the GABAergic and oscillatory abnormalities into the converging disease model and made it possible to discover the causes of some disruptions.
Bromantane, sold under the brand name Ladasten, is an atypical central nervous system (CNS) stimulant and anxiolytic drug of the adamantane family that is related to amantadine and memantine. Medically, it is approved in Russia for the treatment of neurasthenia. Although the effects of bromantane have been determined to be dependent on the dopaminergic and possibly serotonergic neurotransmitter systems, its exact mechanism of action is unknown, and is distinct in its properties relative to typical stimulants such as amphetamine. Bromantane has sometimes been described as an actoprotector.
A monoamine releasing agent (MRA), or simply monoamine releaser, is a drug that induces the release of a monoamine neurotransmitter from the presynaptic neuron into the synapse, leading to an increase in the extracellular concentrations of the neurotransmitter. Many drugs induce their effects in the body and/or brain via the release of monoamine neurotransmitters, e.g., trace amines, many substituted amphetamines, and related compounds.
3-Hydroxymorphinan (3-HM), or morphinan-3-ol, is a psychoactive drug of the morphinan family. It is the racemic counterpart to norlevorphanol.
Adapromine is an antiviral drug of the adamantane group related to amantadine (1-aminoadamantane), rimantadine, and memantine (1-amino-3,5-dimethyladamantane) that is marketed in Russia for the treatment and prevention of influenza. It is an alkyl analogue of rimantadine and is similar to rimantadine in its antiviral activity but possesses a broader spectrum of action, being effective against influenza viruses of both type A and B. Strains of type A influenza virus with resistance to adapromine and rimantadine and the related drug deitiforine were encountered in Mongolia and the Soviet Union in the 1980s.
Butagest, also known as buterol, as well as 3β-hydroxy-6-methyl-17α-hydroxypregna-4,6-dien-20-one 3β-butanoate 17α-acetate or as 6-methyl-17α-hydroxy-δ6-progesterone 3β-butanoate 17α-acetate, is a steroidal progestin which was developed in Russia for potential clinical use but was never marketed. It is a modification of megestrol acetate in which the C3 ketone has been replaced with a C3β butanoyloxy moiety.
