I wouldn't necessary rely on ketamine, N2O, or even mematine or for up-regulating NMDARs.
Effects of exercise on NMDA receptor subunit contributions to bidirectional synaptic plasticity in the mouse dentate gyrus.
We examined synaptic plasticity in the dentate gyrus (DG) of the hippocampus in vitro in juvenile C57Bl6 mice (28-40 days of age), housed in control conditions with minimal enrichment (Controls) or with access to an exercise wheel (Runners). LTP expression was significantly greater in slices from Runners than in those from Controls, but could be blocked by APV, a selective and competitive NMDA receptor antagonist, in both groups. LTP was significantly reduced by NR2B subunit antagonists in both groups. NVP-AAM077, an antagonist with a higher preference for NR2A subunits over NR2B subunits, blocked LTP in slices from Runners and produced a slight depression in Control animals. LTD in the DG was also blocked by APV, but not by either of the NR2B specific antagonists. Strikingly, NVP-AAM077 prevented LTD in Runners, but not in Control animals, suggesting an increased involvement of NR2A subunits in LTD in animals that exercise. NVP-AAM077 did not block LTD in NR2A Knock Out (KO) animals that exercised, as expected. In an attempt to discern whether NMDA receptors located at extrasynaptic sites could play a role in the induction of LTD, DL-TBOA was used to block excitatory amino acid transport and increase extracellular glutamate levels. Under these conditions, LTD was not blocked by the co-application of a specific NR2B subunit antagonist in either group, but NVP-AAM077 again blocked LTD selectively in Runners. These results indicate that NR2A and NR2B subunits play a significant role in LTP in the DG, and that exercise can significantly alter the contribution of NMDA NR2A subunits to LTD.
Individual and combined effects of rhynchophylline and ketamine on proliferation, NMDAR1 and GluA2/3 protein expression in PC12 cells.
Rhynchophylline is an active component of the Uncaria species, which is a member of the Rubiaceae family. Our studies show that the downregulation of N-methyl-d-aspartate (NMDA) receptor subunit GluN2B expression in the nucleus accumbens, amygdala, medial prefrontal cortex, and hippocampal CA1 area by rhynchophylline is beneficial for the treatment of psychological dependence on amphetamines. The individual and combined effects of rhynchophylline and ketamine on proliferation and GluN1 and GluA2/3 protein expression in PC12 cells were investigated. PC12 cells were differentiated into neuron-like cells by treatment with nerve growth factor (50 ng/mL). After treatment for 48 h, differentiated PC12 cell proliferation and GluN1 and GluA2/3 protein expression were analyzed. The viability of PC12 cells was reduced by ketamine at doses of 0.50, 1.00, 1.50, and 2.00 mmol/L, with the viability of cells treated with 1.50 and 2.00 mmol/L of ketamine significantly lower than that of the control cells. However, PC12 cells treated with rhynchophylline showed no toxicity at doses of 0.25, 0.50, 0.75, or 1.00 mmol/L. While GluA2/3 protein expression was upregulated by ketamine, it was not influenced by rhynchophylline. GluN1 protein expression was downregulated by rhynchophylline (1 mmol/L), while treatment with ketamine, either alone or with rhynchophylline, had no effect. These findings demonstrate that rhynchophylline suppresses GluA2/3 expression in ketamine-induced PC12 cells and downregulates GluN1 expression. Ketamine's lack of effect on GluN1 expression offers a partial explanation for ketamine addiction and the anti-addictive properties of rhynchophylline.
Effects of kynurenic acid as a glutamate receptor antagonist in the guinea pig.
Glutamate excitotoxicity is implicated in both the genesis of neural injury and noise-induced hearing loss (NIHL). Acoustic overstimulation may result in excessive synaptic glutamate, resulting in excessive binding to post-synaptic receptors and the initiation of a destructive cascade of cellular events, thus leading to neuronal degeneration and NIHL. The purpose of this study was to determine whether this apparent excitotoxicity can be attenuated by kynurenic acid (KYNA), a broad-spectrum glutamate receptor antagonist, and protect against noise-induced temporary threshold shifts (TTS). Guinea pigs were randomly assigned to three separate groups. Base-line compound action potentials (CAP) thresholds and cochlear microphonics (CM) were recorded. Group I was treated with physiologic saline as a vehicle control applied to the round window membrane that was followed by 110 dB SPL wide-band noise for 90 min. Group II received 5 mM KYNA followed by noise exposure, and group III received 5 mM KYNA alone without noise exposure. Post-drug and noise levels of CAP thresholds and CM were then obtained. Noise exposure in the control group caused a significant temporary threshold shift (TTS) of 30-40 dB across the frequencies tested (from 3 kHz to 18 kHz). Animals that received 5 mM KYNA prior to noise exposure (group II) showed statistically significant protection against noise-induced damage and demonstrated a minimal TTS ranging between 5 and 10 dB at the same frequencies. Animals in group III receiving KYNA without noise exposure showed no change in thresholds. Additionally, cochlear microphonics showed no considerable difference in threshold shifts when controls were compared to KYNA-treated animals. These results show that antagonizing glutamate receptors can attenuate noise-induced TTS, suggesting that glutamate excitotoxicity may play a role in acoustic trauma.
NMDA/glutamate mechanism of magnesium-induced anxiolytic-like behavior in mice.
The anxiolytic-like activity of magnesium in mice during the elevated plus maze (EPM) has been demonstrated previously. In the present study, we examined the involvement of NMDA/glutamate receptor ligands on the magnesium effect on the EPM. We demonstrated that low, ineffective doses of NMDA antagonists (the competitive NMDA antagonist CGP 37849, 0.3 mg/kg; an antagonist of the glycineB sites, L-701,324, 1 mg/kg; a partial agonist of the glycineB sites, D-cycloserine, 2.5 mg/kg; and the non-competitive NMDA antagonist MK-801, 0.05 mg/kg) administered together with an ineffective dose of magnesium (10 mg/kg) evoked a significant increase in the percentage of time spent in the open arm of the maze (an index of anxiety). Moreover, magnesium-induced anxiolytic-like activity (20 mg/kg) was antagonized by D-serine (100 nmol/mouse), an agonist of glycineB site of the NMDA receptor complex. The present study demonstrates the involvement of the NMDA/glutamate pathway in the magnesium anxiolytic-like activity in the EPM in mice, and that this activity particularly involves the glycineB sites.
Effect of exercise training on long-term potentiation and NMDA receptor channels in rats with cerebral infarction
http://www.ncbi.nlm....les/PMC3829711/
Treadmill exercise enhances NMDA receptor expression in mice
http://www.e-jer.org...mber=2013600095
Edited by gamesguru, 17 September 2015 - 10:08 PM.