Nigrostriatal pathway
Encyclopedia
The nigrostriatal pathway is a neural pathway
that connects the substantia nigra
with the striatum
. It is one of the four major dopamine pathways in the brain, and is particularly involved in the production of movement, as part of a system called the basal ganglia
motor loop.
Loss of dopamine neuron
s in the substantia nigra
is one of the main pathological features of Parkinson's disease
, leading to a marked reduction in dopamine function in this pathway. The symptoms of the disease typically do not show themselves until 80-90% of dopamine function has been lost.
This pathway is also implicated in producing tardive dyskinesia
, one of the side-effects of antipsychotic
drugs. These medications (particularly the older typical antipsychotic
s) block D2 dopamine receptor
s in multiple pathways in the brain.
The desired clinical effect of reducing psychotic
symptoms is thought to be associated with blocking dopamine function in the mesolimbic pathway
only. However, as many of these drugs are not selective, they block dopamine in all pathways. When this happens in the nigrostriatal pathway, similar movement problems to those found in Parkinson's disease can occur.
Neural pathway
A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter...
that connects the substantia nigra
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
with the striatum
Striatum
The striatum, also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain. It is the major input station of the basal ganglia system. The striatum, in turn, gets input from the cerebral cortex...
. It is one of the four major dopamine pathways in the brain, and is particularly involved in the production of movement, as part of a system called the basal ganglia
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
motor loop.
Loss of dopamine neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s in the substantia nigra
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
is one of the main pathological features of Parkinson's disease
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
, leading to a marked reduction in dopamine function in this pathway. The symptoms of the disease typically do not show themselves until 80-90% of dopamine function has been lost.
This pathway is also implicated in producing tardive dyskinesia
Tardive dyskinesia
Tardive dyskinesia is a difficult-to-treat form of dyskinesia that can be tardive...
, one of the side-effects of antipsychotic
Antipsychotic
An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
drugs. These medications (particularly the older typical antipsychotic
Typical antipsychotic
Typical antipsychotics are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis...
s) block D2 dopamine receptor
Dopamine receptor
Dopamine receptors are a class of metabotropic G protein-coupled receptors that are prominent in the vertebrate central nervous system . The neurotransmitter dopamine is the primary endogenous ligand for dopamine receptors....
s in multiple pathways in the brain.
The desired clinical effect of reducing psychotic
Psychosis
Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...
symptoms is thought to be associated with blocking dopamine function in the mesolimbic pathway
Mesolimbic pathway
The mesolimbic pathway is one of the dopaminergic pathways in the brain. The pathway begins in the ventral tegmental area of the midbrain and connects to the limbic system via the nucleus accumbens, the amygdala, and the hippocampus as well as to the medial prefrontal cortex...
only. However, as many of these drugs are not selective, they block dopamine in all pathways. When this happens in the nigrostriatal pathway, similar movement problems to those found in Parkinson's disease can occur.
Other dopamine pathways
Other major dopamine pathways include:- mesocortical pathwayMesocortical pathwayThe mesocortical pathway is a neural pathway that connects the ventral tegmentum to the cerebral cortex, particularly the frontal lobes. It is one of the four major dopamine pathways in the brain...
- mesolimbic pathwayMesolimbic pathwayThe mesolimbic pathway is one of the dopaminergic pathways in the brain. The pathway begins in the ventral tegmental area of the midbrain and connects to the limbic system via the nucleus accumbens, the amygdala, and the hippocampus as well as to the medial prefrontal cortex...
- tuberoinfundibular pathwayTuberoinfundibular pathwayThe tuberoinfundibular pathway refers to a population of dopamine neurons in the arcuate nucleus of the mediobasal hypothalamus that project to the median eminence . It is one of the four major dopamine pathways in the brain...
See also
- antipsychoticAntipsychoticAn antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
- dopamineDopamineDopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
- Parkinson's diseaseParkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system...
- Tardive dyskinesiaTardive dyskinesiaTardive dyskinesia is a difficult-to-treat form of dyskinesia that can be tardive...
- StutteringStutteringStuttering , also known as stammering , is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds, syllables, words or phrases, and involuntary silent pauses or blocks in which the stutterer is unable to produce sounds...