China
Africa
Explore chapters and articles related to this topic
Neuro–Endocrine–Immune Dysfunction in the Chronic Pain Patient
Published in Sahar Swidan, Matthew Bennett, Advanced Therapeutics in Pain Medicine, 2020
The N-methyl-D-aspartate (NMDA) receptor has been well-implicated in the development of wind-up. The NMDA receptor is an ionotropic glutamate receptor (glutamate receptor and an ion channel). At normal resting potential, the ionophore channel is blocked by Mg2+. With the Mg2+ block in place, glutamate will not be able to open the channel. However, with repetitive stimulation by AMPA and SP, the Mg2+ block is removed. If secondary glycine or D-serine sites are also occupied, activation of the NMDA receptor by glutamate can then allow entry of Ca2+ and Na+ into the cell, and K+ out of the cell. So not only is the cell depolarized, but there are increased intracellular stores of Ca2+ as well. Wind-up has been prevented by the administration of NMDA receptor antagonists.42–44
Neurotransmitters and Receptors, Ion Channels, G Proteins and Second Messengers
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The NMDA receptor is the most important glutamate receptor. It has four subunits. The central pore is blocked by magnesium and is activated by NMDA. Partial depolarization of the cell membrane is required to remove the Mg++ plug, resulting in the influx of Ca++ ions (Figure 3.7). The NMDA receptor has a role in learning and memory, central sensitization and wind-up or plasticity.
Cognition Enhancers
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Ramneek Kaur, Rashi Rajput, Sachin Kumar, Harleen Kaur, R. Rachana, Manisha Singh
The role of glycine and D-serine as a co-agonist was determined more than 25 years ago (Johnson and Ascher, 1987; Kleckner and Dingledine, 1988). These amino acids bind to GluN1 component of the NMDA receptor and glutamate (the classic agonist) binds to GluN2 subunit. Simultaneous binding of these subunits, that is, GluN1 and GluN2 causes the full activation of NMDA receptor (Laube et al., 1997). There is a release of glutamate from the synaptic bouton during the synaptic transmission and it is anticipated that the obtainability of glutamate extracellular spaces regulates the functioning of the receptor and thereby, affecting the synaptic plasticity. It is applicable for both D-serine (Yang et al., 2003) and glycine (Martina et al., 2004). With aging, the concentrations of D-serine and serine racemase (an enzyme that forms D-serine from L-serine) decrease in hippocampus region (Turpin et al., 2011). This shortcoming can be amended by the addition of D-serine, which helps in restoring the plasticity in hippocampus from mouse model suffering from SAMP8 (senescence accelerated mouse-prone 8) and aged rats (Yang et al., 2005). Further, an addition of D-serine up-regulates the neurogenesis in vitro and in vivo (Sultan et al., 2013).
A systematic review of the efficacy of ketamine for craniofacial pain
Published in Canadian Journal of Pain, 2023
Yasmine Hoydonckx, Tyler McKechnie, Miki Peer, Marina Englesakis, Pranab Kumar
It is hypothesized that CFP syndromes share a mechanism of central sensitization as a cause for pain. Central sensitization is characterized by an increase in neuronal excitability secondary to repetitive stimulation of the nociceptive C-fibers in the trigeminocervical complex and the brain, which is mediated by the activation of N-methyl-d-aspartate (NMDA) receptors.6–8 Activation of the NMDA receptors plays a major role in ongoing pain, opioid-induced hyperalgesia, and mood dysregulation, and it is considered the principal receptor involved in the phenomena of central sensitization and “wind-up,” resulting in hyperalgesia, allodynia, and spontaneous pain.9,10 This central sensitization can be reversed by blockade of these receptors by noncompetitive NMDA antagonists such as ketamine.6,7,10,11
Emerging clinical investigational drugs for the treatment of amyotrophic lateral sclerosis
Published in Expert Opinion on Investigational Drugs, 2023
Loreto Martinez-Gonzalez, Ana Martinez
(NCT04302870) are two FDA-approved drugs. The first one, approved for late stages of Alzheimer´s disease, is a NMDA receptor antagonist that regulates the calcium influx into the neurons. Memantine prolongs lifespan and survival of SOD1G93A mice after chronic treatment [98]. However, this fact could not be confirmed in the first clinical trial where 63 ALS patients were treated with memantine [99]. Trazodone, an antidepressive agent, has recently shown its ability to block the production of toxic proteins in a cellular model that contains the repeated C9orf72 mutations [100]. These two drugs will be study now against placebo looking for a change in decline of ALSFRS-R over 18 months and increase of patients’ survival in the Motor Neurone Disease – Systematic Multi-Arm Adaptive Randomized Trial (MND-SMART) promoted by Anonymized University. This trial is a way to test more than one treatment for ALS at the same time. In the first instance the trial will have 3 arms; drug 1, drug 2 and placebo [101]. Drugs tested in this trial should be already approved for use in other conditions, being memantine and trazodone the two first selected ones. MND-SMART is expected to enroll up to 531 adults with ALS.
Neural Plasticity in the Ventral Tegmental Area, Aversive Motivation during Drug Withdrawal and Hallucinogenic Therapy
Published in Journal of Psychoactive Drugs, 2023
Hector Vargas-Perez, Taryn Elizabeth Grieder, Derek van der Kooy
Another possible route of action of 5-HT2A receptors is the long-term regulation of the expression of NMDA-like glutamate receptors (Zhong, Yuen, and Yan 2008). NMDA receptors are directly related to learning, particularly to the production and maintenance of potentiated glutamatergic signaling. Blockade of NMDA receptors with selective antagonists, such as ketamine, produces a relief of depressive symptoms almost instantaneously after their administration (Lapidus, Soleimani, and Murrough 2013; Niciu et al. 2014). However, because the regulation of the NMDA receptor is at the synaptic level, its therapeutic effects are generally short-term (around a week), and at best a couple of months (Lapidus, Soleimani, and Murrough 2013; Niciu et al. 2014). On the other hand, the long-term effects (more than 6 months (Griffiths et al. 2011)) of the action of agonists at 5-HT2A receptors could be due to a modification in the genetic transcription of glutamatergic NMDA receptors (Yuen et al. 2008), however this hypothesis needs to be corroborated experimentally.