d-Aspartate consumption selectively promotes intermediate-term spatial memory and the expression of hippocampal NMDA receptor subunits

• Published in: Scientific reports Vol. 11; no. 1; p. 6166
• Main Authors: Zachar, Gergely, Kemecsei, Róbert, Papp, Szilvia Márta, Wéber, Katalin, Kisparti, Tamás, Tyler, Teadora, Gáspár, Gábor, Balázsa, Tamás, Csillag, András
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17-03-2021; Nature Publishing Group; Nature Portfolio
• Subjects: 631/378/1595/1554; 631/378/1595/3922; Animal memory; Cell proliferation; Cognitive ability; D-Serine; Doublecortin protein; Glutamic acid receptors (ionotropic); Hippocampus; Humanities and Social Sciences; Memory; Morphometry; multidisciplinary; N-Methyl-D-aspartic acid receptors; Neural stem cells; Neurogenesis; Observational learning; Progenitor cells; Reversal learning; Science; Science (multidisciplinary); Spatial discrimination learning; Spatial memory
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-85360-w

d
-Aspartate (
d
-Asp) and
d
-serine (
d
-Ser) have been proposed to promote early-phase LTP in vitro and to enhance spatial memory in vivo. Here, we investigated the behavioural effects of chronic consumption of
d
-Asp and
d
-Ser on spatial learning of mice together with the expression of NMDA receptors. We also studied the alterations of neurogenesis by morphometric analysis of bromo-deoxyuridine incorporating and doublecortin expressing cells in the hippocampus. Our results specify a time period (3–4 h post-training), within which the animals exposed to
d
-Asp (but not
d
-Ser) show a more stable memory during retrieval. The cognitive improvement is due to elimination of transient bouts of destabilization and reconsolidation of memory, rather than to enhanced acquisition.
d
-Asp also protracted reversal learning probably due to reduced plasticity. Expression of GluN1 and GluN2A subunits was elevated in the hippocampus of
d
-Asp (but not
d
-Ser) treated mice.
d
-Asp or
d
-Ser did not alter the proliferation of neuronal progenitor cells in the hippocampus. The observed learning-related changes evoked by
d
-Asp are unlikely to be due to enhanced proliferation and recruitment of new neurones. Rather, they are likely associated with an upregulation of NMDA receptors, as well as a reorganization of receptor subunit assemblies in existing hippocampal/dentate neurons.