Cannabis is now one of the most commonly used illicit substances among pregnant women. This is particularly concerning since developmental exposure to cannabinoids can elicit enduring neurofunctional and cognitive alterations. This study investigates the mechanisms of learning and memory deficits resulting from prenatal cannabinoid exposure (PCE) in adolescent offspring. The synthetic cannabinoid agonist WIN55,212-2 was administered to pregnant rats, and a series of behavioral, electrophysiological, and immunochemical studies were performed to identify potential mechanisms of memory deficits in the adolescent offspring. Hippocampal-dependent memory deficits in adolescent PCE animals were associated with decreased long-term potentiation (LTP) and enhanced long-term depression (LTD) at hippocampal Schaffer collateral-CA1 synapses, as well as an imbalance between GluN2A- and GluN2B-mediated signaling. Moreover, PCE reduced gene and protein expression of neural cell adhesion molecule (NCAM) and polysialylated-NCAM (PSA-NCAM), which are critical for GluN2A and GluN2B signaling balance. Administration of exogenous PSA abrogated the LTP deficits observed in PCE animals, suggesting PSA mediated alterations in GluN2A- and GluN2B- signaling pathways may be responsible for the impaired hippocampal synaptic plasticity resulting from PCE. These findings enhance our current understanding of how PCE affects memory and how this process can be manipulated for future therapeutic purposes.

Introduction: Extrasynaptic GluN2B N-methyl-D-aspartate receptors (ES-GluN2B) are localized outside synapses and promote excitotoxic signaling, apoptosis, and long-term depression (LTD) in Alzheimer’s disease (AD). Polysialylated neural cell adhesion molecule (PSA-NCAM) physiologically inhibits ES-GluN2B activity, and its downregulation is associated with impaired synaptic plasticity. However, the spatiotemporal changes of ES-GluN2B and PSA-NCAM during brain aging versus AD remain poorly understood.Methods: We investigated GluN2A, GluN2B, ES-GluN2B, and PSA-NCAM expression across brain regions in young and old Tg2576 AD and wild-type (WT) mice. Additional experiments included PSD-95 pulldown assays, analysis of GluN2B phosphorylation at Ser1480, CRISPRa-driven ST8Sia4 upregulation in IMR-32 neuroblastoma cells, and Aβ treatment to assess effects on PSA-NCAM biosynthetic enzymes.Results: Normal aging was associated with decreased GluN2B, increased GluN2A, stable ES-GluN2B, and elevated PSA-NCAM levels. In contrast, AD aging showed elevated ES-GluN2B and reduced PSA-NCAM, particularly in the hippocampus and cortex, with no change in total NCAM expression. PSD-95 pulldown revealed increased extrasynaptic GluN2B in aged AD brains. AD aging was associated with elevated phosphorylation of GluN2B at Ser1480 by casein kinase 2 (CK2), promoting GluN2B redistribution to extrasynaptic sites. CRISPRa-driven ST8Sia4 upregulation increased PSA-NCAM and reduced pGluN2B expression supporting a direct regulatory role for PSA-NCAM in GluN2B trafficking. Additionally, Aβ suppressed PSA-NCAM biosynthetic enzymes ST8Sia4 and UDP-E linking Aβ to impaired polysialylation.Discussion: These findings highlight distinct regulatory patterns of ES-GluN2B and PSA-NCAM in AD versus normal aging and support a model in which impaired PSA-NCAM buffering facilitates pathological ES-GluN2B signaling and plasticity loss in AD progression.

The growing perception that marijuana is safe during pregnancy has led to a marked increase in prenatal cannabis use, raising concerns about its long-term effects on brain development and cognition. This study investigated the consequences of prenatal delta-9-tetrahydrocannabinol (THC) exposure on hippocampal circuit function, synaptic plasticity, and memory in adolescent offspring using a rodent model. We found that prenatal THC exposure resulted in persistent deficits in hippocampal-dependent memory and significant disruptions in synaptic plasticity, including impaired long-term potentiation and increased long-term depression. Electrophysiological analyses revealed reduced AMPAR-mediated synaptic transmission and a shift toward increased inhibitory signaling, suggesting an excitation/inhibition (E/I) imbalance in the hippocampus. These functional changes were accompanied by selective downregulation of postsynaptic glutamatergic proteins (GluA1, GluN2A, GluN2B, and PSD95), while presynaptic glutamate markers remained unchanged. Notably, immunohistochemical and anatomical analyses demonstrated region-specific reorganization of inhibitory networks, including altered distribution and colocalization of cannabinoid 1 receptor (CB₁R) and vesicular GABA transporter (VGAT) across hippocampal subregions. Together, our results reveal that prenatal THC exposure leads to coordinated functional and structural remodeling of hippocampal circuits, producing a lasting E/I imbalance and memory impairments during adolescence. These findings highlight disrupted GABAergic signaling as a potential therapeutic target for mitigating cognitive deficits resulting from prenatal cannabis exposure.

Background: Prenatal cannabinoid exposure (PCE) causes neurodevelopmental impairments affecting learning and memory; however, the receptor-level interactions underlying these cognitive deficits remain poorly understood. This study investigated whether a moderate dose of prenatal Δ⁹-tetrahydrocannabinol (THC) exposure alters the biophysical properties of synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, which are critical mediators of excitatory neurotransmission and synaptic plasticity. Methods: Pregnant Sprague-Dawley rats received a moderate dose (5 mg/kg) of THC or vehicle control via oral gavage throughout gestation and early postnatal development. Single-channel electrophysiological activity of the AMPA receptors (AMPARs) was recorded using patch-clamp techniques on synaptosomal AMPARs reconstituted into artificial lipid bilayers from adolescent offspring. Western blot analysis of GluA1- and GluA2-containing AMPAR subunits and the postsynaptic scaffold protein postsynaptic density 95 (PSD95) was conducted to assess protein levels. Results: Prenatal THC exposure decreased AMPAR open-channel probability, reduced mean open time, increased mean closed time, and altered burst channel activity significantly, without altering GluA1, GluA2, or PSD95 protein levels. Furthermore, the interactive channel-gating activity observed in control synaptosomes was absent in synaptosomes derived from THC-exposed offspring. Conclusions: Prenatal cannabinoid exposure induces early alterations in glutamatergic synaptic function primarily mediated by changes in AMPAR channel kinetics rather than receptor abundance. By identifying AMPAR single-channel dysfunction as a sensitive marker of PCE-induced synaptic disruption, this work provides a mechanistic framework linking prenatal THC exposure to long-term alterations in learning and memory.

Polysialic acid (PSA), a highly negatively charged glycan attached mainly to the neural cell adhesion molecule (NCAM), is emerging as a critical but underrecognized extracellular regulator of glutamatergic neurotransmission. While previous literature has focused on PSA’s developmental roles, increasing evidence indicates that PSA–NCAM also contributes to synaptic plasticity mechanisms in the mature brain. This review integrates evidence from structural biophysics, single-channel electrophysiology, and disease models to explain how PSA modulates glutamate receptor gating to control learning and memory. We synthesize findings from biochemical reconstitution, electrophysiological recordings, and in vivo studies to show that PSA can modulate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor open probability, burst duration, and cooperative gating without affecting conductance, thereby promoting long-term potentiation. Conversely, PSA selectively suppresses GluN2B-containing extrasynaptic N-methyl D-Aspartate (NMDA) receptor activity by lowering open probability and calcium influx, maintaining an optimal balance between potentiation and depression while providing neuroprotection. Disruption of PSA–NCAM signaling in developmental and disease models, including prenatal cannabinoid exposure and neurodegeneration, produces cognitive deficits reversible by PSA restoration. Notably, much of the current evidence derives from in vitro systems, with relatively few studies conducted in vivo, and studies employing PSA mimetics mostly, which should be considered when interpreting physiological relevance. Collectively, the available evidence suggests that PSA functions as an extracellular modulator linking synaptic glycans to glutamate receptor regulation and plasticity related signaling pathways, highlighting the potential importance of extracellular glycan mechanisms in the control of synaptic function.