Antipsychotics represent mainstay treatment of schizophrenia and are also prescribed on- and off-label in other severe mental illnesses. Newer antipsychotic use is associated with severe metabolic side effects such as obesity and type 2 diabetes. Leptin is a hormone secreted by adipose tissue, and it acts on the brain to decrease body weight by reducing food intake and stimulating energy expenditure. Leptin also improves glucose and lipid metabolism. In this study, we examined the short-term impact of olanzapine, a commonly used second-generation antipsychotic, on the central leptin-mediated regulation of energy balance, glucose and lipid metabolism, and hypothalamic kinase activity. Male SD rats were given an acute intracerebroventricular (ICV) injection of either leptin or vehicle, combined with subcutaneous olanzapine or vehicle. As expected, ICV leptin decreased food intake and, importantly, olanzapine did not block this effect. Administration of leptin, olanzapine, or their combination reduced the average respiratory exchange ratio (RER) during the light-cycle, indicating increased fat oxidation. In the dark-cycle, leptin decreased the average RER regardless of olanzapine administration, and in the presence of leptin, olanzapine did not affect the average RER. Olanzapine treatment produced transient glucose intolerance during the IPGTT, an effect no longer observed with leptin co-treatment, though no significant differences in AUC, fasting serum glucose, insulin, or HOMA-IR were observed between any groups. Olanzapine and leptin treatment differentially activated hypothalamic kinases. In conclusion, the regulation of food intake and fuel preference by central leptin remains intact despite acute olanzapine administration, and leptin may transiently attenuate olanzapine-induced glucose intolerance.
Acetaminophen (APAP) produces analgesia through mechanisms that remain poorly understood. Here, we tested the hypothesis that APAP-induced suppression of pathological pain is associated with cannabinoid receptors and activity of enzymes regulating endogenous lipids (diacylglycerol lipase, DAGL; monoacylglycerol lipase, MAGL) including endocannabinoids. APAP suppressed mechanical hypersensitivity in mouse models of post-surgical and inflammatory pain and the DAGL inhibitors (RHC-80267, DO34) and MAGL inhibitor JZL184 blocked APAP's analgesic effects. Global (rimonabant, AM251) but not peripherally restricted (AM6545) cannabinoid receptor antagonists prevented APAP-induced analgesia. APAP increased corticosterone levels >2-fold and reduced prostaglandins >5-fold across the brain and in the paw skin. In addition, APAP reduced up to 39% of signaling lipids detected in the targeted screen in CFA-treated subjects in a tissue-dependent manner. These observations suggest that APAP plays a wider role in endogenous lipid signaling than previously hypothesized and provides novel insight into mechanisms of action.
This Special Issue (SI) is dedicated to the memory of Francesco Di Virgilio, an eminent and extraordinarily gifted scientist who unexpectedly passed away while attending a congress two years ago. Francesco left behind a remarkable legacy of discoveries in the field of purinergic signaling, with particular emphasis on the ATP-sensitive ionotropic P2X7 receptor (P2X7R). We never anticipated that our initiative to organize this SI would generate such overwhelming interest within the purinergic research community. The SI comprises 20 articles, including both original research papers and review articles, focusing primarily on topics closely related to Francesco's scientific interests. The major chapters in this collection of papers are (1) P2XR-mediated signaling as a cause of inflammation, pain, and neuronal development; (2) P2X7Rs in neurodegenerative diseases; (3) ATP-induced changes in astrocytic functions; (4) The enigma of the neuronal P2X7R; (5) Purinergic signaling and cancer neuroscience; and (6) The efficiency of natural products to treat allergic contact dermatitis and high glucose-induced ferroptosis. We hope that the reader will enjoy this brief journey through important aspects of purinergic signaling with the same delight as we felt when compiling this volume.
Striatal neurodegeneration, a prominent pathological feature of several neurological disorders, is associated with progressive behavioral decline alongside cognitive and motor dysfunction, reflecting the critical regulatory role of the striatum in coordinating multiple aspects of brain function. Neuroinflammation, particularly through NF-κB/NLRP3-pathway activation, which triggers the cleavage and subsequent secretion of IL-1β/IL-18, contributes substantially to neuronal injury, with glial activation serving as a key driver, whereas the AMPK/SIRT1-signaling cascade exerts anti-inflammatory and neuroprotective effects. Network pharmacology suggested potential interactions between AMPK/SIRT1-signaling and NF-κB/NLRP3-associated inflammatory and glial pathways. Simvastatin and Ezetimibe possess pleiotropic properties that may modulate these pathways. This research evaluated the neuroprotective potential of Simvastatin and Ezetimibe, given alone or combined, in a striatal neurodegeneration model induced by 3-nitropropionic acid(3-NP) in rats. Adult male Wistar rats were assigned by random selection into six-cohorts (n = 15/group): control-cohort; 3-NP (10 mg/kg/day, administered intraperitoneally for 21 days) vehicle-cohort; and 3-NP-treated cohorts receiving Simvastatin (10 or 20 mg/kg, orally), Ezetimibe (10 mg/kg, orally), or a combination of both (10 mg/kg each). Treatments were administered 1h before 3-NP injection. Exposure to 3-NP induced marked oxidative stress, neuroinflammation, gliosis, neurotransmitter disturbances, histopathological alterations, and behavioral deficits. In comparison to the 3-NP-vehicle-cohort, Simvastatin and/or Ezetimibe enhanced AMPK/SIRT1-signaling, suppressed NF-κB/NLRP3 inflammasome activation, reduced glial reactivity, restored neurotransmitter homeostasis, and improved behavioral and histopathological outcomes. The combination regimen consistently produced the most pronounced protective effects. Collectively, Simvastatin and Ezetimibe attenuate 3-NP-induced striatal neurodegeneration, possibly through modulation of AMPK/SIRT1-associated neuroinflammatory and glial signaling pathways, warranting further evaluation in additional experimental models.
Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is a central feature of stress-related affective disorders, and corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) initiate neuroendocrine stress responses. Although the α7 nicotinic acetylcholine receptor (α7 nAChR) has been implicated in emotional regulation, its role in PVN CREB/CRH signaling and anxiety- and depressive-like behaviors remains unclear. Here, using male C57BL/6 mice, we found that pharmacological activation of α7 nAChR with PNU282987 induced anxiety- and depressive-like behaviors under control conditions and further exacerbated behavioral abnormalities following chronic restraint stress (CRS), without significantly affecting locomotor activity. PNU282987 also increased CREB phosphorylation and CRH expression in the PVN and elevated serum CRH, adrenocorticotropic hormone (ACTH), and corticosterone (CORT) levels. Conversely, in CRS mice, the α7 nAChR-preferring antagonist methyllycaconitine (MLA) increased sucrose preference, OFT center exploration, and EPM open-arm time while reducing TST immobility. These behavioral effects were accompanied by reduced PVN CREB phosphorylation and CRH expression and decreased serum CRH, ACTH, and CORT levels. Notably, α7 nAChR protein abundance in the PVN was not significantly altered by CRS or drug treatment, suggesting that functional receptor activation rather than receptor upregulation may drive downstream signaling. Moreover, the CREB-mediated transcription inhibitor 666-15 attenuated PNU282987-induced behavioral abnormalities, serum CRH elevation, and PVN CRH upregulation. These findings indicate that α7 nAChR activation promotes anxiety- and depressive-like behaviors associated with enhanced PVN CREB phosphorylation, CRH upregulation, and HPA axis hyperactivity. CREB-associated CRH signaling may therefore represent a neuroendocrine mechanism linking α7 nAChR activation to stress-related affective disturbances.
PURPOSE:The present study investigated the neuroprotective effects of orientin, a natural flavonoid with antioxidant and anti-inflammatory properties, loaded into chitosan nanoparticles (CNPs-Orientin) in a unilateral 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease. The study further evaluated behavioral performance, histopathological alterations, tyrosine hydroxylase (TH) immunoreactivity, oxidative stress, inflammatory cytokines, and apoptosis- and survival-related signaling proteins. MATERIALS AND METHODS:Seventy-two male Sprague-Dawley rats (220-260 g) were randomly assigned into nine experimental groups (n = 8/group): Control, Orientin, CNPs, CNPs-Orientin, 6-OHDA, 6-OHDA + L-DOPA, 6-OHDA + Orientin, 6-OHDA + CNPs, and 6-OHDA + CNPs-Orientin. Parkinsonism was induced by unilateral stereotaxic injection of 6-OHDA into the substantia nigra pars compacta. Drug treatments were initiated after lesion induction and continued for 14 consecutive days. Behavioral, histopathological, immunohistochemical, biochemical, and Western blot analyses were subsequently performed. RESULTS:6-OHDA administration caused marked motor impairment, neuronal degeneration, reduced TH immunoreactivity, increased α-synuclein and Beclin-1 immunoreactivity, increased oxidative stress, elevated inflammatory cytokines, increased apoptosis-related protein expression, and suppression of antioxidant defense mechanisms. Treatment with CNPs-Orientin significantly improved behavioral performance, preserved TH-positive neurons, reduced α-synuclein-positive cell density and Beclin-1-positive DAB area, reduced neuronal degeneration, decreased MDA, TNF-α, IL-1β, IFN-γ, NF-κB, and Caspase-3 levels, while restoring SOD, GSH, Bcl-2, PI3K, Akt, and mTOR protein expression. Overall, CNPs-Orientin produced greater neuroprotective effects than free orientin alone. CONCLUSION:Chitosan nanoparticle-mediated delivery substantially enhanced the neuroprotective efficacy of the natural flavonoid orientin against 6-OHDA-induced dopaminergic neurodegeneration. The observed protective effects were associated with reduced oxidative stress, inflammation, apoptosis, and changes in PI3K/Akt/mTOR-related protein expression.
Relapse triggered by withdrawal memory is the important challenge in addiction therapy, with somatic withdrawal symptoms acting as its physiological substrate. Clarifying the relevant neural mechanisms is vital for relapse intervention, yet the link between basolateral amygdala (BLA) astrocytes and somatic withdrawal responses remains elusive. In this study, we combined 3D-AI behavioral analysis, in vivo calcium recording, and astrocyte specific inhibition using HPMCA2w/b (a calcium extrusion pump) in male C57BL/6J mice to study the role of BLA astrocytes in morphine withdrawal. We observed that BLA astrocytes were activated during morphine withdrawal conditioning. Inhibiting their intracellular calcium signaling reduced CPA scores. 3D-AI behavioral analysis showed a significantly locomotor suppression in withdrawal mice. Further, we identified two categories of behaviors: (1) jumping and standing, which were associated with the naloxone-induced withdrawal during the acquisition phase; (2) sniffing and self-grooming, which appeared during both naloxone-induced withdrawal during the conditioning phase and spontaneous withdrawal during memory retrieval phase. Astrocytic calcium signals were elevated during the occurrences of all four behaviors. Notably, astrocyte inhibition reversed the locomotor suppression during spontaneous withdrawal in post-conditioning and selectively suppressed jumping and standing during conditioning in withdrawal mice, but not affected sniffing or self-grooming. These findings indicate that BLA astrocytes are critical for association of context cues with aversive state of morphine withdrawal and they participate in some of somatic withdrawal signs during high-dose naloxone-precipitated morphine withdrawal. This study provides new insights into withdrawal for further research on opioid addiction.
Cocaine use disorder is marked by strong interindividual variability, yet the molecular determinants underlying vulnerability in females remain poorly characterized. Here, we adapted a statistical model previously validated in males to classify female rats exposed to a cocaine-induced conditioned place preference paradigm into two subgroups: those expressing cocaine reward (CPP expression (CPPE), score >74 s) and those showing no preference ((nCPPE), score between -19 and 53 s), independently of estrous-cycle influences. Despite identical cocaine exposure, two clear behavioral phenotypes emerged, with no differences in baseline emotional-like, cognitive, or hedonic-like measures. Whole-transcriptome sequencing of the nucleus accumbens during CPP expression and following reinstatement revealed extensive transcriptional differences between subgroups. CPPE females showed strong upregulation of immediate early genes (Egr1, Egr2, Egr4) and enrichment of pathways implicated in addiction-related neuroplasticity, including MAPK, cAMP signalling, axon guidance, and glutamatergic transmission. Reinstatement further differentiated CPPE and nCPPE rats, notably through persistent IEG activation and modulation of circadian regulators such as Rorb and Per2, suggesting a potential involvement of circadian-related mechanisms signature in cocaine vulnerability. Additional novel candidates, including SLC transporters and genes involved in synaptic organization, were identified in resilient females. Together, these findings provide an integrated behavioral and transcriptomic characterization of cocaine-induced interindividual variability in female rats and highlight molecular mechanisms that may contribute to vulnerability and resilience to cocaine's rewarding effects.
Burn injury-induced pain (BIP) is a complex condition whose spinal mechanisms remain incompletely understood. Although spinal glucagon-like peptide-1 receptor (GLP-1R) signaling has been implicated in pain modulation, its contribution to BIP remains unclear. Using a mouse model of second-degree burn injury, we characterized nociceptive behaviors, spinal glial responses, and the temporal and cellular distribution of GLP-1R using immunoblotting, immunofluorescence, and RNAscope in situ hybridization. We then evaluated the antinociceptive effects of intrathecal semaglutide, their sensitivity to pharmacological GLP-1R antagonism, and the functional contribution of endogenous enkephalin/δ-opioid receptor (DOR) signaling. Burn injury increased spinal GLP-1R expression during the peak phase of pain hypersensitivity. GLP-1R immunoreactivity and Glp1r transcripts showed a substantial association with GFAP-positive astrocytic profiles, while detectable signals were also present in microglia and neurons. Intrathecal semaglutide attenuated mechanical allodynia and thermal hyperalgesia, and these effects were reduced by pharmacological GLP-1R antagonism. Acute semaglutide responsiveness was also observed in female mice. Semaglutide increased spinal Penk mRNA and enkephalin immunoreactivity in vivo and increased Penk expression and extracellular enkephalin levels in primary spinal astrocyte-enriched cultures. In spinal tissue, enkephalin immunoreactivity was more frequently associated with GFAP-positive profiles than with Iba1-or NeuN-positive profiles. Moreover, enkephalin neutralization and DOR antagonism attenuated semaglutide-induced antinociception. Together, these findings support a functional spinal enkephalin/DOR pathway linked to intrathecal semaglutide treatment and consistent with GLP-1R involvement in BIP.
Mesolimbic endocannabinoid (eCB) signaling impacts reward-seeking behaviors that rely on incentive salience. We previously showed that systemic enhancement of 2-arachidonoylglycerol (2-AG) using the monoacylglycerol lipase (MAGL) inhibitor MJN110 robustly decreased the latency of responding to reward-predictive incentive cues (ICs) and collecting the reward, as well as the choice to respond to the IC. Here we sought to determine the contribution of the endocannabinoids 2-AG and anandamide in the ventral tegmental area (VTA) in mediating incentive salience processes. We microinfused MJN110 or PF3845, a fatty acid amide hydrolase (FAAH) inhibitor, into the VTA to increase 2-AG and anandamide, respectively in male rats. These rats were trained to nosepoke during an 8-sec audiovisual IC to receive a 10% sucrose reward. We found that while intra-VTA PF3845 had little effect on responding to the IC, intra-VTA MJN110 specifically increased only the choice to respond without impacting the vigor (e.g., rapidity) of the response towards either the IC or the sucrose reward itself. This contrasts with our previous work in which systemic MJN110 treatment enhanced choice, and vigor to both the IC and reward. Further, the intra-VTA MJN110 enhancement of responding to ICs was blocked by the CB1 receptor antagonist rimonabant. Our results suggest that increasing 2-AG, but not anandamide, in the VTA selectively enhances the choice to respond to cues predicting a reward. However, the effects of systemic MJN110 in enhancing the vigor of responding cannot be attributed to VTA 2-AG signaling.
Orofacial neuropathic pain (ONP) is a common complication following nerve injury driven by peripheral mechanisms. N-methyl-D-aspartate receptors (NMDARs), particularly NR2A and NR2B, are involved in pain processing in the trigeminal ganglion (TG), but their downstream pathways in ONP remain unclear. Here, chronic constriction injury of the infraorbital nerve (CCI-ION) was established in wild-type mice and in mice with TG-targeted adeno-associated virus-mediated conditional deletion of NR2A or NR2B. CCI-ION upregulated NR2A and NR2B in the TG, as verified by quantitative reverse transcription-polymerase chain reaction, Western blot, and immunofluorescence, with increased immunoreactivity in both TG neurons and satellite glial cells (SGCs). Conditional deletion of either subunit attenuated CCI-ION-induced mechanical hypersensitivity. Molecular analyses showed that these subunits were preferentially associated with distinct transcriptional modules: following CCI-ION, NR2A deletion counteracted the suppression of Cyp1a1, Cyp2e1, and Zfp593, whereas NR2B deletion counteracted the upregulation of Slc6a1 and Tlr2 and the downregulation of Cacna1g. N-methyl-D-aspartate (NMDA) stimulation and subsequent NR2A or NR2B knockdown by siRNA produced directionally consistent changes in Neuro-2a cells and primary TG-derived SGCs. Kinase-inhibitor profiling in Neuro-2a cells revealed distinct response patterns. Local pharmacological induction of CYP2E1 or inhibition of TLR2 or SLC6A1 in the TG attenuated CCI-ION-induced mechanical hypersensitivity. Overall, peripheral NMDAR signaling following CCI-ION is associated with subunit-specific transcriptional modules involving both neuronal and glial compartments. These findings identify candidate molecular targets for ONP.
Genome-wide association studies on patients with depression have identified FYN and FYB, an FYN-binding protein, as being linked to depression. We have reported that experimental manipulations in gene expression in the medial prefrontal cortex (mPFC) alter stress-induced object recognition impairments in animals. Therefore, we examined the impact of alterations in FYN and FYB expression in the mPFC of adult male rats on resistance to stress-induced impairments in object recognition. Animals with virus-mediated knockdown or overexpression of Fyn in the mPFC were subjected to either a brief 20-min restraint with 20 intermittent tail shocks, which does not induce object recognition impairment, or a prolonged 60-min restraint with 60 intermittent tail shocks, which does. In an object recognition task, control rats maintained intact object recognition following a brief stress, whereas rats with Fyn knockdown or overexpression in the mPFC showed impaired object recognition. Prolonged stress impaired object recognition in both control rats and rats with Fyn knockdown or overexpression. Additionally, rats with Fyn knockdown in the mPFC exhibited fewer c-Fos-positive cells in the mPFC in response to brief stress, accompanied by a trend toward increased c-Fos in the amygdala compared with control rats. Fyn knockdown also reduced Fyb expression in the mPFC. Furthermore, Fyb knockdown in the mPFC impaired object recognition following brief stress, suggesting that the observed effects are consistent with involvement of a coupled Fyn-Fyb signaling axis rather than Fyn alone. These findings suggest that altered Fyn-related signaling in the mPFC may underlie the resistance to stress-induced object recognition impairments.
Rett syndrome (RTT) and MECP2 Duplication syndrome (MDS) are disorders caused by decreases and increases in the expression of the transcriptional regulator, Methyl CpG Binding Protein 2 (MeCP2), respectively. We previously performed an mRNA expression profiling study of the temporal cortex region from patients diagnosed with RTT and corresponding age, postmortem interval, and sex-matched controls. These studies identified a significant reduction in the mRNA expression of the histamine H3 receptor (HRH3). In the current manuscript, we expanded receptor profiling to additional RTT patient brain samples representing distinct MECP2 mutations and confirmed significantly reduced levels of HRH3 receptor expression in the majority of patients compared to controls. Using mouse models of RTT and MDS, we observed antiparallel changes in Hrh3 receptor expression across various brain areas, with Hrh3 expression being reduced in RTT model animals and increased in a mouse model of MDS. We then evaluated both a small molecule agonist of the H3 receptor, (R)-α-methylhistamine (RAMH), and the H3 receptor inverse agonist, pitolisant (Wakix®), in RTT and MDS models, respectively, to determine impacts on phenotypes in these disease models. Our results show little to no efficacy of RAMH or pitolisant in modulating behavioral responses in either mouse line.
Infralimbic cortex (IL) pyramidal neurons (PNs) have been implicated in suppressing instrumental cocaine seeking, yet their causal contribution to Pavlovian extinction and subsequent retrieval remains unclear. Using CaMKIIα promoter-driven chemogenetics, we bidirectionally modulated IL PN activity across extinction training, extinction expression, and primed reinstatement in a cocaine-conditioned place preference (CPP) paradigm in male mice. Manipulating IL PN activity during the extinction phase did not alter the progressive reduction of CPP across intermediate probe sessions, suggesting no effects on the formation of extinction. In contrast, acute inhibition of IL PNs impaired extinction expression, whereas stimulation did not further enhance performance, indicating that extinction retrieval is dependent on a sufficient level of IL PN activity that is likely achieved under baseline conditions. During cocaine-primed reinstatement, acute inhibition of IL PNs exacerbated the recovery of conditioned responses, while stimulation was critical to prevent reinstatement, suggesting that IL-mediated behavioral suppression is sensitive to the motivational state. Although coordinated activity in IL projection targets, including the nucleus accumbens shell, the basolateral and central amygdala, and the lateral entorhinal cortex, was observed during extinction expression and reinstatement, this activity did not explain additional variance beyond IL PN activity. Together, these findings highlight IL PNs as a central node in the expression of Pavlovian extinction and in shaping vulnerability to cocaine-induced relapse-like behavior.
Photocaged adenosine A1 receptor (A1R) agonists combined with spatiotemporally selective illumination represents a promising therapeutic strategy for mesial temporal lobe epilepsy (mTLE). This ex vivo study investigated whether the A1R agonist N6-cyclopentyladenosine (CPA) suppresses hippocampal excitability in the intrahippocampal kainic acid (IHKA) mouse model and whether photocaged CPA (cCPA) enables subregion-selective and closed-loop reduction of hippocampal excitability. Hippocampal slices from male IHKA and saline-injected control mice were exposed to CPA (10-900 nM) while electrically evoked field postsynaptic potentials (fPSPs) were recorded in dentate gyrus (DG) and CA1. We evaluated fPSP slope (neurotransmission strength) and population spike (PS) amplitude (postsynaptic activation). Next, hippocampal slices were superfused with 3 μM cCPA while focally illuminating DG or CA1 to investigate spatial targeting. Finally, a cCPA-based closed-loop system was tested to maintain PS amplitude at 50% of baseline. While CPA-induced fPSP slope reduction was similar in CA1 between IHKA and control slices, it was significantly reduced in DG for IHKA compared to control slices. This difference was absent when extracellular K+ was increased from 3.25 mM to 5.5 mM. In 5.5 mM K+, CPA similarly decreased excitability in DG and CA1 in IHKA and control slices. Focal CPA photorelease inhibited neurotransmission with limited effects in non-illuminated regions, indicating subregion-selective inhibition. Closed-loop control stabilized DG PS amplitude at the predefined level in IHKA slices. Adenosine A1R activation robustly reduces excitability in the hippocampus from IHKA mice. Photopharmacology enables spatially controlled and closed-loop inhibition to maintain stable DG output, offering a targeted treatment strategy for mTLE.
Maternal behaviour is characterized by increased motivation for pups, which facilitates the expression of behaviours promoting offspring survival and development. Motivated behaviours are critically dependent on brain dopamine systems, thus, understanding its functioning is necessary to elucidate maternal reward brain processing. The activity of dopamine systems is controlled by the inhibitory GABA cells of the tail of the ventral tegmental area or rostromedial tegmental nucleus (tVTA/RMTg). This brain region is involved in reward and avoidance behaviour, among other functions, however, its role in maternal behaviour remains poorly understood. In the present study, we assess the effect of pharmacological manipulation of the tVTA/RMTg on maternal behaviour in postpartum female rats. To this end, pregnant Sprague-Dawley female rats underwent stereotaxic implantation of a guide cannula in the tVTA/RMTg. During the first week after delivery, female rats received intra-tVTA/RMTg microinjections of vehicle and/or several pharmacological agents (glutamate, DAMGO, muscimol, oxytocin or atosiban) in a cross-design. Our results reveal that pharmacological activation and inhibition of the tVTA/RMTg can increase or decrease maternal behaviour, respectively, by altering some specific behaviours, such as pup retrieval, pup exploration or time spent in nest. Otherwise, modulation of the oxytocinergic transmission at the tVTA/RMTg reveals mild effects on maternal behaviour and the observed effect depend on the oxytocin dose. Overall, our results reveal an involvement of the tVTA/RMTg in maternal reward processing, since its activation or inhibition can critically modulate maternal behaviour.
Sex differences in the prevalence, age of onset of symptoms, and symptom presentation have been widely described in autism spectrum disorders, yet the mechanisms underlying these sex differences remain poorly characterized. Exposing rats prenatally to valproic acid (VPA) is widely used as a model to study autism-like phenotypes. Using this model, sex-specific neuroanatomical and functional characteristics were examined in adolescent rats. We found sex differences in cortical pyramidal neuron complexity, spine density, and morphology in VPA-prenatally exposed animals. The expression of autism has been linked to various processes such as inflammation, cell signalling, endothelial function, and myelination. Sex-specific analysis of cortical gene expression showed that male VPA-prenatally exposed rats had elevated expression of genes related to neuropeptide signaling (Pdyn, Adora2a, Drd2), whereas female VPA-prenatally exposed rats had lower expression of genes related to vascular permeability (Angptl4, Cldn5) and inflammation (Cyr61, Usp18). Dimethyl fumarate, an activator of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and clinically approved to treat multiple sclerosis, alleviated VPA-induced behavioural alterations in object recognition, anxiety-like behaviour, and social behaviour in female VPA-exposed rats. In addition, dimethyl fumarate corrected the associated VPA-induced changes in neuronal oscillatory power and cross-frequency coupling and suppressed microglial activity, with the latter occurring selectively in female animals. Together, these findings indicate sex as an essential consideration in the development of novel pharmacotherapies for autism. Dimethyl fumarate had therapeutic properties in VPA-prenatally exposed female rats, however further studies examining its therapeutic efficacy in other models of autism are required.
