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Physiology of the Pain System
Published in Sahar Swidan, Matthew Bennett, Advanced Therapeutics in Pain Medicine, 2020
The limbic system is a set of brain structures on either side of the thalamus that directs emotion, behavior, motivation, long-term memory, and olfaction. The mesolimbic pathway is part of the reward circuit. Dopaminergic neurons in the ventral tegmental area (VTA) of the midbrain project to the forebrain nucleus accumbens (NAc). Burst firing of dopaminergic neurons into the NAc serves as a reward signal and is inhibited by tonic GABA input.15 Opioids inhibit GABAergic tone on these neurons, while pain relief directly engages dopamine circuitry.15 The mesolimbic pathway has been implicated in depression, anxiety, pain sensation, anticipation of analgesia or placebo-induced analgesia, and chronic pain.16 Different types of pain can impact different aspects of the VTA and result in either activation or inhibition. In this way, dopamine release is variable based on various pain signals.16 These dopaminergic pathways are variably altered with stress as well as opioids. Dynorphin and the kappa opioid receptor can play a role in impairing dopamine release in the Na.16
Antipsychotic Drugs
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Harleen Kaur, Ramneek Kaur, Varsha Rani, Kanishka Sharma, Pawan Kumar Maurya
Risperidone is an antipsychotic drug of second generation having affinity for receptors like α1, α2, D2, H1, and 5-HT2A. Although the mechanism of action is not fully agreed, the recent theories focus mainly on receptors like 5-HT2A and D2 (Edwards, 1994). From the perspective of pharmacodynamics, the antipsychotics share a common characteristic that is the ability to reduce neurotransmission of dopaminergic. According to the theory of dopamine in depression, overactivity of mesolimbic pathway explains the positive symptoms of schizophrenia. Cognitive and negative symptoms of schizophrenia are associated to dysfunction of this pathway (Swerdlow and Koob, 1987).
Biological Basis of Behavior
Published in Mohamed Ahmed Abd El-Hay, Understanding Psychology for Medicine and Nursing, 2019
The mesolimbic pathway transmits dopamine from the ventral tegmental area to the nucleus accumbens, the amygdala, and the hippocampus. This is achieved by neurons that have their soma in the ventral tegmental area projecting axons out to the named areas. It is significantly involved with reward and pleasure and is hence of great interest in studies of depression, motivation and addition, where it has been linked with alcohol, nicotine, and cocaine.
Potassium channel modulators and schizophrenia: an overview of investigational drugs
Published in Expert Opinion on Investigational Drugs, 2023
Meghan Musselman, Eric Huynh, Rachana Kelshikar, Eric Lee, Mohammed Malik, Justin Faden
In-depth reviews about prominent hypotheses of schizophrenia symptom development have been explored elsewhere and are beyond the scope of this review [13–15]. The most pervasive theory regarding the development of schizophrenia is the dopamine hypothesis, which holds that dopamine hyperactivity in the mesolimbic pathway from the ventral tegmental area to the ventral striatum contributes to positive symptoms of schizophrenia, whereas dopamine deficit in the mesocortical pathway contributes to negative symptoms [13,14,16]. Most available antipsychotic medications are dopamine antagonists thought to exert efficacy in treating the positive symptoms of schizophrenia by blocking D2 receptors in the mesolimbic pathway. The extrapyramidal side effects associated with these medications result from the blockade of D2 receptors in the nigrostriatal pathway from the substantia nigra to the dorsal striatum [9]. Evidence supporting the dopamine hypothesis includes the observation that stimulants, such as methamphetamine and cocaine, increase the release of dopamine and induce positive symptoms like that of schizophrenia [17]. Additionally, [18F]-FDOPA PET imaging studies have consistently demonstrated an increase in dopamine synthesis capacity in the associative striatum of patients with schizophrenia [18–20]. Moreover, greater striatal dopamine synthesis capacity corresponds with greater symptom severity and yet also predicts a greater response to antipsychotic dopamine D2 receptor antagonists [18,21].
Amantadine and memantine: a comprehensive review for acquired brain injury
Published in Brain Injury, 2020
Heather M. Ma, Ross D. Zafonte
A third proposed mechanism for increasing the level of severely injured patients’ clinical arousal and awareness is through targeted dopamine enhancement. The theoretical basis of this concept involved pharmacologically targeting three of the four major dopaminergic pathways in the brain (15): The mesolimbic pathway, associated with motivation, learning, and memory.The nigrostriatal pathway, involved in initiation and velocity of movement.The mesocortical pathway, involved in motivation or activation, planning, and temporal organization, as well as associated with cortical tone and attention.
Comparing the effectiveness of behavioral interventions in adults with co-occurring tobacco and substance use disorders: a systematic review of literature
Published in Journal of Social Work Practice in the Addictions, 2020
John Boatner, Timothy Rice, David Patterson, Phyllis Thompson
A neurobiological perspective can offer a lens from which tobacco dependence and other concomitant substance disorders are understood. For example, the neurotransmitter dopamine is known to have a direct relationship with a person’s learning and motivation via a neurobiological process that occurs in the ventral tegmental area of the mid-brain. This is where dopamine is released through the mesolimbic pathway and where the rewarding sensation of pleasure is experienced (Simpkins & Simpkins, 2013). All forms of tobacco contain the psychostimulant drug, nicotine, which acts through the dopaminergic mesolimbic pathway and elicits feelings of enhanced mood and a heightened sense of alertness (Fagerström, 2002). Nicotine, directly and indirectly, activates the dopaminergic pathway that is also influenced by any commonly misused drug, offering a neurobiological basis from which high levels of tobacco use co-occurs and can be better understood (Guydish et al., 2015). Ultimately, the pervasive release of dopamine through the mesolimbic pathway reinforces addictive behavior(s), which includes the use of tobacco and psychoactive substances.