Polyphenol Modulation of Synaptosomal Ca²⁺ Signaling at NMDA Receptors

Authors

Holiqova M.A.

Nаtiоnаl Univеrsitу оf Uzbеkistаn named after M. Ulugbek, Tashkent, Almazar 100174, Uzbekistan
Muratova M.X.

Nаtiоnаl Univеrsitу оf Uzbеkistаn named after M. Ulugbek, Tashkent, Almazar 100174, Uzbekistan
Yuldasheva G.K.

Nаtiоnаl Univеrsitу оf Uzbеkistаn named after M. Ulugbek, Tashkent, Almazar 100174, Uzbekistan
Kоzоkоv I. B.

Institute of Biophysics and Biochemistry at the National University of Uzbekistan, 100174, Tashkent, Uzbekistan
Khоshimоv N.N.

Institute of Biophysics and Biochemistry at the National University of Uzbekistan, 100174, Tashkent, Uzbekistan
Erkinov I. O.

Impuls Medical Institute, 160114, Namangan, Uzbekistan
Kosimova Z.T.

Nаmаngаn Stаtе Univеrsitу. Namangan region, Namangan, 160119, Uzbekistan
Rakhimov R.N.

Institute of Bioorganic Chemistry, 100125, Tashkent, Uzbekistan
Murodov S.S.

Samarkand Regional Center for Pedagogical Excellence, Uzbekistan

DOI:

https://doi.org/10.37547/ajbspi/Volume06Issue03-07

Keywords:

Alzheimer’s disease NMDA receptor synaptosome

Abstract

Background: NMDA receptor (NMDAR) overactivation and the resulting Ca²⁺ overload represent a convergent biophysical pathway implicated in synaptic failure in Alzheimer’s disease (AD) [1]. Memantine is a clinically used uncompetitive NMDAR antagonist that targets the channel pore, but ligand‑site modulation may offer a distinct pharmacological profile.

Methods: Rat brain synaptosomes were isolated by differential centrifugation and loaded with Fluo‑4 AM to monitor cytosolic Ca²⁺ signals. NMDAR‑dependent responses were evoked with glutamate (50 μM) and glycine (50 μM). The polyphenol G‑41 was tested across 10–100 μM and concentration–response relationships were analyzed using the Hill equation (n = 6 independent preparations). To map the target site(s), we assessed interactions with Zn²⁺ and Mg²⁺ (5 μM; additional tests 10–100 μM in the AD condition), and compared G‑41 effects with memantine (50 μM). GABAergic context was probed using GABA (100 μM), picrotoxin (50 μM), diazepam (10–100 μM), and phenobarbital (10–100 μM).

Results: G‑41 produced concentration‑dependent suppression of both glutamate‑ and glycine‑driven Ca²⁺ signals. The apparent IC₅₀ values were 63.9 ± 2.13 μM for the glutamate‑dependent component and 42.93 ± 3.06 μM for the glycine‑dependent component, with steep Hill coefficients (|nH| ≈ 3.35–6.27), consistent with multi‑step receptor gating and/or integrated Ca²⁺ handling. Zn²⁺ and Mg²⁺ did not measurably alter the G‑41 effect, supporting a mechanism not mediated by these allosteric regulators. G‑41 did not overlap with the memantine pore site, suggesting a pharmacological profile distinct from open‑channel blockade.

Conclusions: G‑41 is a synaptosome‑level modulator of NMDAR‑dependent Ca²⁺ dynamics with evidence for dual modulation of glutamate and glycine binding sites and minimal interaction with Zn²⁺/Mg²⁺ allosteric regulation or the memantine pore site. These properties justify follow‑up electrophysiology and binding studies, as well as in vivo validation in AD‑relevant models.

References

Bezprozvanny I, Mattson MP. Neuronal calcium mishandling and the pathogenesis of Alzheimer’s disease. Trends Neurosci. 2008;31:454–463.

Shankar GM, Li S, Mehta TH, et al. Amyloid‑β protein dimers isolated directly from Alzheimer’s brains impair synaptic plasticity and memory. Nat Med. 2008;14:837–842.

Hansen KB, Yi F, Perszyk RE, et al. Structure, function, and allosteric modulation of NMDA receptors. J Gen Physiol. 2018;150:1081–1105.

Lipton SA. Paradigm shift in neuroprotection by NMDA receptor blockade: memantine and beyond. Nat Rev Drug Discov. 2006;5:160–170.

Khoshimov, N. N., Saidmurodov, S. A., & Rakhimov, R. N. (2021). The Mechanism of action of polyphenol on changes in the dynamics of calcium in the synaptosomes of the rat brain against the background of glutamate. The American journal of applied sciences, 3 (03), 48-55.

Mukhtorov, A. A., Mamadaminov, R. R., Khoshimov, N. N., Nasirov, K. E., Rakhimov, R. N., & Gaybullo, L. X. (2022). Regulation of transport of Ca2+ NMDA-receptors in rat brain synaptosomes under the influence of polyphenols. European Journal of Medicine, 10(1), 3-11.

Rebas E, Rzajew J, Radzik T, et al. Polyphenol compounds as modulators of neuroprotective pathways. Chem Biol Interact. 2020;319:109010.

Campos‑Esparza MR, Sanchez‑Gomez MV, Matute C. Molecular mechanisms of neuroprotection by polyphenols. Int J Mol Sci. 2009;10:391–415.

Rakhimov, R. N., Khoshimov, N. N., Kurbanova, A. D., Komilov, K. U., Makhmanov, D. M., Kadirova, S. O., & Abdulladjanova, N. G. (2021). Isolation of new ellagitannins from plants of Euphorbiaceous and its effect on calcium transport in the nerve cell of the rat brain. Annals of the Romanian Society for Cell Biology, 25(6), 2758-2768.

Khoshimov, N. N., Rahimova, G. L., Mirzakulov, S. O., Azizov, V. G., Abduboqiyev, A. R., & Rakhimov, R. N. (2021). Study of the Neuroprotective Properties of Biologically Active Compounds. Annals of the Romanian Society for Cell Biology, 25(6), 2775-2782.

Khoshimov, N. N., & Nasirov, K. E. (2017). Action of Cytisinum on the Transport Mediators and Calcium Channel of Glutamatergic Neurotransmitter Systems of the NMDA Receptor. European Journal of Medicine, (5-2), 56-63.

Khoshimov, N. N., Raimova, G. M., Nasirov, K. E., Rakhimov, R. N., & Azizov, V. G. (2020). The Effect of Sp-6 On The Transport of Mediators of NMDA-Receptors and Ca 2+-channels in Synaptosomes of rat brain. European Journal of Molecular & Clinical Medicine, 7(3), 2435-2446.

Khoshimov, N. N., Kabil, N. E., & Eshbakova, K. A. (2015). Research influence biological active agents in the course of regulation of functional activity of platelets and system of a haemostasis. European Journal of Medicine, 2, 88-93.

Cotman CW, Matthews DA, Taylor D, Lynch G. Synaptic rearrangement in hippocampus. Brain Res. 1974;63:205–210.

Krysanova Z, Krisanova N, Borisova T. Synaptosomal glutamate uptake and release. Neurochem Int. 2007;51:451–456.

Goutelle S, Maurin M, Rougier F, et al. The Hill equation: a review of its capabilities in pharmacology. Fundam Clin Pharmacol. 2008;22:633–648.

Zaidi A. Plasma membrane Ca²⁺‑ATPases: targets of oxidative stress in brain aging and neurodegeneration. World J Biol Chem. 2010;1:271–280.

Brazhe AR, Verisokin AYu, Postnov DE, et al. Changes in sodium‑calcium exchanger mobility in aged neurons. Neurochem Int. 2018;120:80–87.

Khoshimov, N. N., Mukhtorov, A. A., Nasirov, K. E., Rakhimov, R. N., & Mamadaminov, R. R. (2022). Effeсts of Рolyрhenols on Сhanges in the Transрort of Сa2+ NMDA-reсeрtors Under the Influenсe of L-glutamate against the Baсkground of Alzheimer’s Disease. Journal of Рharmaceutical Negative Results, 13, 1322-1332.

Khoshimov, N. N., Nasirov, K. E., Raimova, G. M., Musaeva, M. K., Azizov, V. G., Тuraev AS, M. S., ... & Abdusalоmоv Sh, A. (2021). Study of the effect of polysaccharides on hemostasis. The American journal of medical sciences and pharmaceutical research, 3(01), 131-138.

Numonjonovich, K. N., Baxtiyarovich, K. I., Ugli, D. J. I., Salimovich, K. S., Ugli, M. A. A., Ugli, O. M. M., ... & Nurillayevich, R. R. (2024). Еffесt of Pоlyphеnоls on Сhаngеs in thе Hеmоstаtiс Systеm of Blооd Plаsmа in Hеаlthy and Mоdеl Rаts with Аlzhеimеr’s Disеаsе. Trends in Sciences, 21(9), 8081-8081.

Ugli, D. J. I., Bakhtiyarovich, K. I., Numonjonovich, K. N., Erkinovich, N. K., Madmuradovna, R. G., Abdugaparovich, M. A., ... & Raxmankulovna, A. N. (2025). The Influence of Polyphenols on Calcium Dynamics in Synaptosomes of Model Rats with Attention Deficit Hyperactivity Disorder of Varying Ages. Trends in Sciences, 22(9), 10434-10434.