The NMDA receptor modulator zelquistinel durably relieves behavioral deficits in three mouse models of autism spectrum disorder

Modulation of neuroinflammation and oxidative stress by Echinacea purpurea extract: Therapeutic potential in maternal separation-induced autism spectrum disorder

BACKGROUND

Autism Spectrum Disorder (ASD) is defined by ongoing problems in social interaction and communication and repetitive, constrained behavior patterns. The link between oxidative stress (OS) and inflammation with ASD has been shown in previous studies. E. purpurea is well-known for its potential antioxidant and anti-inflammatory pharmacological properties. In this study, we aimed to evaluate the effects of E. purpurea hydroalcoholic extract on autistic-like behaviors following a mouse model of maternal separation (MS) stress, focusing on possible anti-neuroinflammation and antioxidative stress.

METHODS

70% hydro-ethanolic extract was macerated from the aerial parts of E. purpurea. Standardization was done by determining the amount of chicoric acid in the extract using the UHPLC method. Then, behavioral analysis was done on 75 male mice that underwent MS. Mice were treated with normal saline or 75, 150, and 300 mg/kg of the extract. Sociability behaviors and stereotyping behaviors have been evaluated. Also, their total antioxidant capacity (TAC), nitrite levels, and malondialdehyde (MDA) were measured in the hippocampus. In addition, the expression of inflammatory factors, including interleukin-1 (IL-1), NLRP3, and TLR4, has been determined by quantitative real-time PCR (qRT-PCR). Data were analyzed after collection using PRISM statistical software.

RESULTS

Our findings indicated that MS caused autistic-like behaviors in mice (increased sociability index and social preference index) and increased repetitive behaviors (increased number of buried marbles). These autistic-like behaviors are associated with increased MDA, nitrite, over-expression of inflammatory genes, decreased MDA, nitrite, over-expression of inflammatory genes, and decreased TAC in the hippocampus. E. purpurea extract significantly reversed these adverse effects of MS.

CONCLUSION

The results of this study showed that E. purpurea extract might reduce autistic-like behaviors in MS by attenuating neuroinflammation and oxidative stress states.

Zelquistinel acts at an extracellular binding domain to modulate intracellular calcium inactivation of N-methyl-d-aspartate receptors

Stinels are a novel class of N-methyl-d-aspartate glutamate receptor (NMDAR) positive allosteric modulators. We explored mechanism of action and NR2 subtype specificity of the stinel zelquistinel (ZEL) in HEK 293 cells expressing recombinant NMDARs. ZEL potently enhanced NMDAR current at NR2A (EC50 = 9.9 ± 0.5 nM) and NR2C-containing (EC50 = 9.7 ± 0.6 nM) NMDARs, with a larger ceiling enhancement at NR2B-NMDAR (EC50 = 35.0 ± 0.7 nM), while not affecting NR2D-containing NMDARs. In cells expressing NR2A and NR2C-containing NMDARs, ZEL exhibited an inverted-U dose-response relation, with a low concentration enhancement and high concentration suppression of NMDAR currents. Extracellular application of ZEL potentiated NMDAR receptor activity via prolongation of NMDAR currents. Replacing the slow Ca2+ intracellular chelator EGTA with the fast chelator BAPTA blocked ZEL potentiation of NMDARs, suggesting an action on intracellular Ca2+-calmodulin-dependent inactivation (CDI). Consistent with this mechanism of action, removal of the NR1 intracellular C-terminus, or intracellular infusion of a calmodulin blocking peptide, blocked ZEL potentiation of NMDAR current. In contrast, BAPTA did not prevent high-dose suppression of current, indicating this effect has a different mechanism of action. These data indicate ZEL is a novel positive allosteric modulator that binds extracellularly and acts through a unique long-distance mechanism to reduce NMDAR CDI, eliciting enhancement of NMDAR current. The critical role that NMDARs play in long-term, activity-dependent synaptic plasticity, learning, memory and cognition, suggests dysregulation of CDI may contribute to psychiatric disorders such as depression, schizophrenia and others, and that the stinel class of drugs can restore NMDAR-dependent synaptic plasticity by reducing activity-dependent CDI.

Acute, chronic and conditioned effects of intranasal oxytocin in the mu-opioid receptor knockout mouse model of autism: Social context matters

Autism Spectrum Disorders (ASD) are neurodevelopmental disorders whose diagnosis relies on deficient social interaction and communication together with repetitive behaviours. Multiple studies have highlighted the potential of oxytocin (OT) to ameliorate behavioural abnormalities in animal models and subjects with ASD. Clinical trials, however, yielded disappointing results. Our study aimed at assessing the behavioural effects of different regimens of OT administration in the Oprm1 null mouse model of ASD. We assessed the effects of intranasal OT injected once at different doses (0.15, 0.3, and 0.6 IU) and time points (5, 15, and 30 min) following administration, or chronically, on ASD-related behaviours (social interaction and preference, stereotypies, anxiety, nociception) in Oprm1+/+ and Oprm1-/- mice. We then tested whether pairing intranasal OT injection with social experience would influence its outcome on ASD-like symptoms, and measured gene expression in the reward/social circuit. Acute intranasal OT at 0.3 IU improved social behaviour in Oprm1-/- mice 5 min after administration, with limited effects on non-social behaviours. Chronic (8-17 days) OT maintained rescuing effects in Oprm1 null mice but was deleterious in wild-type mice. Finally, improvements in the social behaviour of Oprm1-/- mice were greater and longer lasting when OT was administered in a social context. Under these conditions, the expression of OT and vasopressin receptor genes, as well as marker genes of striatal projection neurons, was suppressed. We detected no sex difference in OT effects. Our results highlight the importance of considering dosage and social context when evaluating the effects of OT treatment in ASD.