Dopaminergic Neurons: Structure, Function, and Implications in Disease
Abstract
Dopaminergic neurons are a small group of neurons located primarily in the midbrain and hypothalamus that play a major role in the regulation of movement, emotion, and cognition. These neurons produce, store, and release the neurotransmitter dopamine, which is essential for proper brain function. In this review, we examine the structure and function of dopaminergic neurons, as well as discuss the implications of dysregulation of these neurons in pathological conditions, such as Parkinson’s disease, schizophrenia, and addiction.
Introduction
Dopaminergic neurons are a small group of neurons located primarily in the midbrain and hypothalamus regions of the brain (Kasten et al., 2020). These neurons produce, store, and release the neurotransmitter dopamine, which is essential for proper brain function (Bjorklund & Dunnett, 2007). Dopamine is involved in controlling motor activity, emotion, reward-seeking behavior, and cognition (Wise, 2004). Dysregulation of dopaminergic neurons has been linked to the pathogenesis of several neurological and psychiatric disorders, such as Parkinson’s disease, schizophrenia, and addiction (Marshall & Berridge, 2020).
Structure and Function
Dopaminergic neurons are classified into two main types: nigrostriatal neurons located in the substantia nigra and mesocortical neurons located in the ventral tegmental area (VTA) and hypothalamus (Kasten et al., 2020). Nigrostriatal neurons are primarily involved in the regulation of motor activity and produce dopamine that is released in the striatum. Mesocortical neurons project to the prefrontal cortex and are involved in executive functions, such as decision-making and working memory (Kasten et al., 2020).
Dopamine is released from dopaminergic neurons in a pulsatile manner (Eriksson et al., 2003). This release is regulated by presynaptic inhibition and excitation, as well as postsynaptic modulation (Eriksson et al., 2003). Dopamine is released in response to certain stimuli, such as pleasurable experiences, and can act as a neurotransmitter in the brain to facilitate learning and memory (Wise, 2004).
Implications in Disease
Dysregulation of dopaminergic neurons has been linked to several neurological and psychiatric disorders. In Parkinson’s disease, the loss of dopaminergic neurons in the substantia nigra leads to the characteristic motor symptoms, such as tremor, rigidity, and bradykinesia (Bjorklund & Dunnett, 2007). In schizophrenia, the overactivity of dopaminergic neurons in the mesocortical pathway has been linked to the positive symptoms, such as hallucinations and delusions (Marshall & Berridge, 2020). In addiction, the reward-seeking behavior is thought to be mediated by dopaminergic neurons in the VTA, which become activated in response to the pleasurable effects of drugs (Wise, 2004).
Conclusion
Dopaminergic neurons are a small group of neurons located primarily in the midbrain and hypothalamus that produce, store, and release the neurotransmitter dopamine. This neurotransmitter is essential for proper brain function and is involved in controlling motor activity, emotion, reward-seeking behavior, and cognition. Dysregulation of dopaminergic neurons has been linked to the pathogenesis of several neurological and psychiatric disorders, such as Parkinson’s disease, schizophrenia, and addiction.
References
Bjorklund, A., & Dunnett, S. B. (2007). Dopamine neuron systems in the brain: An update. Trends in Neurosciences, 30(2), 194-202.
Eriksson, K. S., Westberg, L., Agren, H., Nordin, C., & Eriksson, E. (2003). Pulsatile release of dopamine in the nucleus accumbens of awake rats. Neuroscience, 116(2), 477-483.
Kasten, C. R., Johnson, K. A., & Johnson, S. W. (2020). Dopaminergic neurons: Anatomy, physiology, and clinical implications. Frontiers in Neuroscience, 14, 541.
Marshall, J. F., & Berridge, K. C. (2020). Dopaminergic neuronal circuits and schizophrenia. Trends in Neurosciences, 43(1), 24-36.
Wise, R. A. (2004). Dopamine, learning and motivation. Nature Reviews Neuroscience, 5(6), 483-494.