Introduction and Objective: Obesity and type 2 diabetes (T2D) are closely linked comorbidities that elevate stroke risk and worsen stroke outcomes. Thus, the continuously expanding obesity/T2D prevalence results in a large population in need of therapies to reduce stroke-related disability. Glucagon-like peptide receptor (GLP-1R) agonists improve stroke outcome in obese/T2D animal models through weight loss. However, whether new, more efficacious dual glucagon/GLP-1R agonists can potentiate this effect is unknown. We addressed this question experimentally using survodutide, a long-acting dual glucagon/GLP-1R agonist, currently in phase 3 trials for obesity and metabolic dysfunction-associated steatohepatitis (MASH). Methods: Obesity/T2D (body weight > 50 grams, fasting glucose > 7 mmol/L, insulin resistance) was induced in C57bl6/j mice by 6 months of high fat diet. Then, mice received daily 15 nmol/kg s.c. survodutide or vehicle for 4 weeks followed by middle cerebral artery occlusion to induce stroke. A pair-fed group with caloric intake matched to survodutide was included to distinguish improved stroke outcome mediated by GLP-1R-driven anorexia from that driven by glucagon-induced effects. Stroke outcome was evaluated via weekly motor/sensory tests for 4 weeks and via measuring infarct volume. Data were analyzed by two-tailed t-test or one-way ANOVA followed by Tukey’s post-hoc test. Results: Survodutide induced ≈30% weight loss, resolved hyperglycemia (4.5-6 mmol/L) and improved insulin sensitivity (p<0.0001 vs. vehicle and vs. pair-fed). Survodutide significantly improved stroke outcome via food-intake independent effects by enhancing paretic forepaw grip strength (p<0.0001 vs. vehicle, p = 0.003 vs. pair-fed) and lateralized sensorimotor integration (p=0.0014 vs. vehicle, p = 0.0015 vs. pair-fed), without affecting stroke volume. Conclusion: We showed that survodutide-mediated weight loss markedly improves stroke outcome in obese/T2D mice, suggesting that it can add secondary cardiovascular benefit when used to treat people living with obesity and MASH. Disclosure E. Vercalsteren: None. T. Klein: Employee; Current; Boehringer Ingelheim International GmbH. C. Patrone: None. V. Darsalia: Research Support; Current; Boehringer Ingelheim International GmbH. Funding Boehringer Ingelheim

Abstract Background Type 2 diabetes worsens functional outcome after stroke, severely affecting the rehabilitation processes, with no therapy available for this medical problem. Main text. Weight loss is an effective strategy for managing type 2 diabetes, with some studies also showing that it can reduce cardiovascular and stroke risk in this population. Recent animal studies suggest that weight loss induced by a diet change or pharmacologically (via the activation of the glucagon-like peptide 1 receptor) also improves functional outcome after stroke. Today, however, no clinical study has yet addressed this question. This issue is important to address since type 2 diabetes is one of the strongest risk factors for stroke and the growing prevalence of diabetes is leading to an increasing number of stroke patients with type 2 diabetes who will require effective therapies. Here, we discuss recent findings showing the positive effects of weight loss in type 2 diabetes and its cardiovascular complications, underlining the need to perform new clinical studies specifically focused on understanding the potential therapeutic role of weight loss to improve functional outcomes after stroke. Conclusions In summary, this debate underscores a critical clinical gap in current post-stroke care strategies and highlights the potential for weight loss as a novel treatment paradigm to improve functional stroke outcomes in type 2 diabetes. If validated in clinical studies, this approach will significantly improve the quality of life of many stroke patients with type 2 diabetes.

Prestroke hyperglycemia and insulin resistance (IR) independently correlate with poor stroke outcomes in type 2 diabetes (T2D), although their causative effect is undetermined. Interestingly, an increasing body of evidence points toward the importance of IR in determining stroke outcomes. Filling this gap is fundamental to identifying effective anti-T2D strategies to improve stroke prognosis in people with T2D. The aim of this study was to determine experimentally whether normalizing IR rather than hyperglycemia before stroke improves stroke outcomes in T2D. To address this research question, hyperglycemia or IR was normalized with intermediate-acting insulin or long-acting selective glucagon receptor agonist (La-GCGRa), respectively, in obese/T2D mice before inducing stroke. Functional recovery (primary outcome) was assessed by neurological testing. Systemic inflammation, infarct size, and neuroinflammation (secondary outcomes) were assessed by ELISA and immunohistochemistry, respectively. The results showed that insulin treatment normalized hyperglycemia without affecting IR and did not improve functional recovery. On the contrary, La-GCGRa normalized IR without affecting hyperglycemia and improved functional recovery. This effect occurred in association with reduced systemic and stroke-induced neuroinflammation. Neither treatment affected infarct size. The data demonstrate that targeting IR in T2D is crucial for improving stroke outcomes and may have significant implications for human therapy.Article Highlights Hyperglycemia and insulin resistance independently correlate with poor stroke outcomes in type 2 diabetes, although their causative role is unclear. The aim of this study was to determine experimentally whether normalizing insulin resistance rather than hyperglycemia before stroke improves stroke outcomes in type 2 diabetes. To answer this question, we specifically normalized either hyperglycemia or insulin resistance in obese, type 2 diabetic mice before inducing stroke. We show that targeting insulin resistance rather than hyperglycemia before stroke in type 2 diabetes is crucial to improving stroke outcomes.

Background/objectives: Being overweight increases the predisposition to obesity and type 2 diabetes (T2D), which significantly elevate stroke risk and the likelihood of severe post-stroke disability. Dietary nitrate (NO3−) supplementation can mitigate obesity and metabolic impairments, making it a promising approach to halt overweight people from developing overt obesity/T2D, thereby potentially also improving stroke outcome. We determined whether NO3− supplementation prevents overweight mice from progressing into obesity and T2D and whether this intervention improves stroke outcome. Methods: An overweight condition was induced via 6 weeks of a high-fat diet (HFD), after which animals were randomized to either a HFD or a HFD with NO3− supplementation. After 24 weeks, when HFD-mice without NO3− developed obesity and T2D, all animals were subjected to transient middle cerebral artery occlusion and stroke outcome was assessed via behavioral testing and infarct size. The effect of NO3− on post-stroke neuroinflammation, neurogenesis, and neovascularization was analyzed by immunohistochemistry. Results: Sustained NO3− supplementation in overweight mice did not prevent obesity or insulin resistance. However, it attenuated weight gain, prevented hyperglycemia, and significantly improved functional recovery after stroke, without affecting infarct size. Moreover, NO3− decreased post-stroke neuroinflammation by reducing microglial infiltration. NO3− did not affect stroke-induced neurogenesis or vascularization. Conclusion: These results highlight the potential of NO3− supplementation to prevent metabolic impairment in the overweight population and improve stroke prognosis in this large group of people at risk of stroke and severe stroke sequelae.

Type 2 diabetes is associated with worsened stroke outcome and lasting disability. The underlying mechanisms are undetermined, and no therapy is available. We experimentally investigated whether pharmacologically targeting obesity, which is highly prevalent in type 2 diabetes, before stroke enhances neurological recovery in type 2 diabetes. To induce weight loss, we employed the glucagon-like peptide 1 receptor (GLP-1R) agonist semaglutide and the neuropeptide Y receptor Y2 (NPY2R) agonist BI8271, which potentiates GLP-1R-mediated weight loss. We also investigated potential acute neuroprotective effects induced by these treatments, independently of metabolic regulation. C57BL/6J mice were fed with a high-fat diet for 5 months to induce obesity and features of type 2 diabetes (i.e. hyperglycaemia and insulin resistance). Weight loss was induced by 4-week administration of semaglutide and/or BI8271. As a control for the effect of weight loss, a vehicle (PBS)-treated group was switched to standard diet to achieve the same weight range and the same percentage weight loss within the same time frame as those receiving semaglutide/BI8271. Thereafter, mice were subjected to stroke by transient middle cerebral artery occlusion (tMCAO). Stroke recovery (the primary outcome) was assessed by measuring the recovery of grip strength and the lateralised sensorimotor integration. Brains and serum were collected, and stroke volume and serum IGF-1 levels were quantified (secondary outcomes). In additional studies, type 2 diabetic mice were subjected to tMCAO and injected with semaglutide and/or BI8271 1 and 24 h after reperfusion. Acute neuroprotection (the primary outcome) was assessed by a grip strength test and by quantifying stroke volume and the number of surviving neuronal nuclear marker (NeuN)-positive neurons. We report that pre-stroke weight loss by GLP-1R activation, and more potently by dual co-activation of GLP-1 and NPY2 receptors, is a pharmacologically targetable mechanism, upstream of glycaemic regulation, through which post-stroke recovery is achieved. Moreover, we show that post-stroke recovery in type 2 diabetes is inversely associated with peripheral IGF-1 levels. Finally, GLP-1R and NPY2R activation can also improve stroke recovery through acute neuroprotection if they are given acutely after stroke, independently of their metabolic effects. The diabetes and obesity epidemics are increasing the incidence of stroke, and consequently the need for treatments to improve stroke outcome. Our results indicate that clinically used type 2 diabetes treatments could be employed in a preventive role to improve stroke outcome by exerting dual pharmacological action: weight loss and acute neuroprotection. These findings could have novel therapeutic implications for many people.

Type-2 diabetes (T2D) worsens stroke recovery, amplifying post-stroke disabilities. Currently, there are no therapies targeting this important clinical problem. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are potent anti-diabetic drugs that also efficiently reduce cardiovascular death and heart failure. In addition, SGLT2i facilitate several processes implicated in stroke recovery. However, the potential efficacy of SGLT2i to improve stroke recovery in T2D has not been investigated. Therefore, we determined whether a post-stroke intervention with the SGLT2i Empagliflozin could improve stroke recovery in T2D mice. T2D was induced in C57BL6J mice by 8 months of high-fat diet feeding. Hereafter, animals were subjected to transient middle cerebral artery occlusion and treated with vehicle or the SGLTi Empagliflozin (10 mg/kg/day) starting from 3 days after stroke. A similar study in non diabetic mice was also conducted. Stroke recovery was assessed using the forepaw grip strength test. To identify potential mechanisms involved in the Empagliflozin-mediated effects, several metabolic parameters were assessed. Additionally, neuronal survival, neuroinflammation, neurogenesis and cerebral vascularization were analyzed using immunohistochemistry/quantitative microscopy. Empagliflozin significantly improved stroke recovery in T2D but not in non-diabetic mice. Improvement of functional recovery was associated with lowered glycemia, increased serum levels of fibroblast growth factor-21 (FGF-21), and the normalization of T2D-induced aberration of parenchymal pericyte density. The global T2D-epidemic and the fact that T2D is a major risk factor for stroke are drastically increasing the number of people in need of efficacious therapies to improve stroke recovery. Our data provide a strong incentive for the potential use of SGLT2i for the treatment of post-stroke sequelae in T2D.

Obesity and Type 2 diabetes (T2D) are known to exacerbate cerebral injury caused by stroke. Metabolomics can provide signatures of metabolic disease, and now we explored whether the analysis of plasma metabolites carries biomarkers of how obesity and T2D impact post-stroke recovery. Male mice were fed a high-fat diet (HFD) for 10 months leading to development of obesity with T2D or a standard diet (non-diabetic mice). Then, mice were subjected to either transient middle cerebral artery occlusion (tMCAO) or sham surgery and allowed to recover on standard diet for 2 months before serum samples were collected. Nuclear magnetic resonance (NMR) spectroscopy of serum samples was used to investigate metabolite signals and metabolic pathways that were associated with tMCAO recovery in either T2D or non-diabetic mice. Overall, after post-stroke recovery there were different serum metabolite profiles in T2D and non-diabetic mice. In non-diabetic mice, which show full neurological recovery after stroke, we observed a reduction of isovalerate, and an increase of kynurenate, uridine monophosphate, gluconate and N6-acetyllysine in tMCAO relative to sham mice. In contrast, in mice with T2D, which show impaired stroke recovery, there was a reduction of N,N-dimethylglycine, succinate and proline, and an increase of 2-oxocaproate in serum of tMCAO versus sham mice. Given the inability of T2D mice to recover from stroke, in contrast with non-diabetic mice, we propose that these specific metabolite changes following tMCAO might be used as biomarkers of neurophysiological recovery after stroke in T2D.

Type 2 diabetes (T2D) impairs post-stroke recovery, and the underlying mechanisms are unknown. Insulin resistance (IR), a T2D hallmark that is also closely linked to aging, has been associated with impaired post-stroke recovery. However, whether IR worsens stroke recovery is unknown. We addressed this question in mouse models where early IR, with or without hyperglycemia, was induced by chronic high-fat diet feeding or sucrose supplementation in the drinking water, respectively. Furthermore, we used 10-month-old mice, spontaneously developing IR but not hyperglycemia, where IR was normalized pharmacologically pre-stroke with Rosiglitazone. Stroke was induced by transient middle cerebral artery occlusion and recovery was assessed by sensorimotor tests. Neuronal survival, neuroinflammation and the density of striatal cholinergic interneurons were also assessed by immunohistochemistry/quantitative microscopy. Pre-stroke induction and normalization of IR, respectively, worsened and improved post-stroke neurological recovery. Moreover, our data indicate a potential association of this impaired recovery with exacerbated neuroinflammation and a decreased density of striatal cholinergic interneurons. The global diabetes epidemic and population aging are dramatically increasing the percentage of people in need of post-stroke treatment/care. Our results suggest that future clinical studies should target pre-stroke IR to reduce stroke sequelae in both diabetics and elderly people with prediabetes.

Microvascular pathology in the brain is one of the suggested mechanisms underlying the increased incidence and progression of neurodegenerative diseases in people with type 2 diabetes (T2D). While accumulating data suggest a neuroprotective effect of antidiabetics, the underlying mechanisms are unclear. Here, we investigated whether two clinically used antidiabetics, the dipeptidyl peptidase-4 inhibitors (DPP-4i) linagliptin and the sulfonylurea glimepiride, restore T2D-induced brain vascular pathology. Microvascular pathology was examined in the striatum of mice fed for 12 months with either normal chow diet or a high-fat diet (HFD) to induce T2D. A subgroup of HFD-fed mice was treated with either linagliptin or glimepiride for 3 months before the sacrifice. We demonstrate that T2D caused leakage of the blood-brain barrier (BBB), induced angiogenesis and reduced pericyte coverage of microvessels. However, linagliptin and glimepiride recovered the BBB integrity and restored the pericyte coverage differentially. Linagliptin normalised T2D-induced angiogenesis and restored pericyte coverage. In contrast, glimepiride enhanced T2D-induced angiogenesis and increased pericyte density, resulting in proper vascular coverage. Interestingly, glimepiride reduced microglial activation, increased microglial-vascular interaction, and increased collagen IV density. This study provides evidence that both DPP-4 inhibition and sulfonylurea reverse T2D-induced BBB leakage which may contribute to the antidiabetic neurorestorative effects.

Glucagon-like peptide-1 (GLP-1) is a peripheral incretin and centrally active peptide produced in the intestine and nucleus tractus solitarii (NTS), respectively. GLP-1 not only regulates metabolism but also improves cognition and is neuroprotective. While intestinal GLP-1-producing cells have been well characterized, less is known about GLP-1-producing neurons in NTS. We hypothesized that obesity-induced type 2 diabetes (T2D) impairs the function of NTS GLP-1-producing neurons and glycemia normalization counteracts this effect. We used immunohistochemistry/quantitative microscopy to investigate the number, potential atrophy, and activation (cFos-expression based) of NTS GLP-1-producing neurons, in non-diabetic versus obese/T2D mice (after 12 months of high-fat diet). NTS neuroinflammation was also assessed. The same parameters were quantified in obese/T2D mice treated from month 9 to 12 with two unrelated anti-hyperglycemic drugs: the dipeptidyl peptidase-4 inhibitor linagliptin and the sulfonylurea glimepiride. We show no effect of T2D on the number and volume but increased activation of NTS GLP-1-producing neurons. This effect was partially normalized by both anti-diabetic treatments, concurrent with decreased neuroinflammation. Increased activation of NTS GLP-1-producing neurons could represent an aberrant metabolic demand in T2D/obesity, attenuated by glycemia normalization. Whether this effect represents a pathophysiological process preceding GLP-1 signaling impairment in the CNS, remains to be investigated.

Stress and negative emotions evoked by social relationships and working conditions, frequently accompanied by the consumption of addictive substances, and metabolic and/or genetic predispositions, negatively affect brain function. One of the affected structures is nucleus accumbens (NAc). Although its function is commonly known to be associated with brain reward responses and addiction, a growing body of evidence also suggests its role in some mental disorders, such as depression and schizophrenia, as well as neurodegenerative diseases, such as Alzheimer’s, Huntington’s, and Parkinson’s. This may result from disintegration of the extensive connections based on numerous neurotransmitter systems, as well as impairment of some neuroplasticity mechanisms in the NAc. The consequences of NAc lesions are both morphological and functional. They include changes in the NAc’s volume, cell number, modifications of the neuronal dendritic tree and dendritic spines, and changes in the number of synapses. Alterations in the synaptic plasticity affect the efficiency of synaptic transmission. Modification of the number and structure of the receptors affects signaling pathways, the content of neuromodulators (e.g., BDNF) and transcription factors (e.g., pCREB, DeltaFosB, NFκB), and gene expression. Interestingly, changes in the NAc often have a different character and intensity compared to the changes observed in the other parts of the basal ganglia, in particular the dorsal striatum. In this review, we highlight the role of the NAc in various pathological processes in the context of its structural and functional damage, impaired connections with the other brain areas cooperating within functional systems, and progression of the pathological processes.

Background Glucagon-like peptide-1 receptor (GLP-1R) activation can decrease stroke risk in people with type 2 diabetes (T2D). Moreover, animal studies have shown the efficacy of GLP-1R agonists to counteract stroke-induced acute brain damage. Whether GLP-1R activation can also improve stroke recovery during the post-acute, chronic phase after stroke, however, remains to be determined. We investigated whether post-acute, chronic administration of the GLP-1R agonist Exendin-4 improves poststroke recovery and examined possible underlying mechanisms in T2D and non-T2D mice. Methods We induced stroke via transient middle cerebral artery occlusion (tMCAO) in T2D/obese mice (8 months of high-fat diet) and age-matched controls. Exendin-4 was administered daily for 8 weeks from day 3 after tMCAO. We assessed functional recovery by weekly upper-limb grip strength tests, while insulin sensitivity and glycemia were evaluated at 4 and 8 weeks after tMCAO. Neuronal cell death, stroke-induced neurogenesis, neuroinflammation, potential atrophy of GABAergic, parvalbumin + interneurons, poststroke vascular remodeling and fibrotic scar formation were investigated by immunohistochemistry. Results Exendin-4 entirely normalized the T2D-induced impairment of forepaw grip strength recovery. The recovery correlated with the normalization of glycemia and insulin sensitivity. We also show that Exendin-4 counteracted the T2D-induced atrophy of parvalbumin + interneurons and decreased microglia activation. In addition, Exendin-4 normalized density and pericyte coverage of microvessels and restored fibrotic scar formation in T2D mice. In non-T2D mice the recovery effect of Exendin-4 was minor. Conclusion This study demonstrates that post-acute, chronic GLP-1R activation mediates neurological recovery after stroke in T2D mice likely through the normalization of glucose metabolism and neuroplasticity mechanisms as well as improved vascular remodeling in the recovery phase. The results promote launching clinical trials investigating whether GLP-1R agonists improve the efficacy of rehabilitation after stroke in people with T2D.

Background Post-stroke functional recovery is severely impaired by type 2 diabetes (T2D). This is an important clinical problem since T2D is one of the most common diseases. Because weight loss-based strategies have been shown to decrease stroke risk in people with T2D, we aimed to investigate whether diet-induced weight loss can also improve post-stroke functional recovery and identify some of the underlying mechanisms. Methods T2D/obesity was induced by 6 months of high-fat diet (HFD). Weight loss was achieved by a short- or long-term dietary change, replacing HFD with standard diet for 2 or 4 months, respectively. Stroke was induced by middle cerebral artery occlusion and post-stroke recovery was assessed by sensorimotor tests. Mechanisms involved in neurovascular damage in the post-stroke recovery phase, i.e. neuroinflammation, impaired angiogenesis and cellular atrophy of GABAergic parvalbumin (PV)+ interneurons were assessed by immunohistochemistry/quantitative microscopy. Results Both short- and long-term dietary change led to similar weight loss. However, only the latter enhanced functional recovery after stroke. This effect was associated with pre-stroke normalization of fasting glucose and insulin resistance, and with the reduction of T2D-induced cellular atrophy of PV+ interneurons. Moreover, stroke recovery was associated with decreased T2D-induced neuroinflammation and reduced astrocyte reactivity in the contralateral striatum. Conclusion The global diabetes epidemic will dramatically increase the number of people in need of post-stroke treatment and care. Our results suggest that diet-induced weight loss leading to pre-stroke normalization of glucose metabolism has great potential to reduce the sequelae of stroke in the diabetic population.

Background and aims Insulin resistance contributes to the development of type 2 diabetes (T2D) and is also a cardiovascular risk factor. The aim of this study was to investigate the potential association between insulin resistance measured by estimated glucose disposal rate (eGDR) and risk of stroke and mortality thereof in people with T2D. Materials and methods Nationwide population based observational cohort study that included all T2D patients from the Swedish national diabetes registry between 2004 and 2016 with full data on eGDR and categorised as following: < 4, 4–6, 6–8, and ≥ 8 mg/kg/min. We calculated crude incidence rates and 95% confidence intervals (CIs) and used multiple Cox regression to estimate hazard ratios (HRs) to assess the association between the risk of stroke and death, according to the eGDR categories in which the lowest category < 4 (i.e., highest grade of insulin resistance), served as a reference. The relative importance attributed of each factor in the eGDR formula was measured by the R 2 (± SE) values calculating the explainable log-likelihoods in the Cox regression. Results A total of 104 697 T2D individuals, 44.5% women, mean age of 63 years, were included. During a median follow up-time of 5.6 years, 4201 strokes occurred (4.0%). After multivariate adjustment the HRs (95% CI) for stroke in patients with eGDR categories between 4–6, 6–8 and > 8 were: 0.77 (0.69–0.87), 0.68 (0.58–0.80) and 0.60 (0.48–0.76), compared to the reference < 4. Corresponding numbers for the risk of death were: 0.82 (0.70–0.94), 0.75 (0.64–0.88) and 0.68 (0.53–0.89). The attributed relative risk R 2 (± SE) for each variable in the eGDR formula and stroke was for: hypertension (0.045 ± 0.0024), HbA1c (0.013 ± 0.0014), and waist (0.006 ± 0.0009), respectively. Conclusion A low eGDR (a measure of insulin resistance) is associated with an increased risk of stroke and death in individuals with T2D. The relative attributed risk was most important for hypertension.

Abstract Inflammation plays a central role in stroke-induced brain injury. The alpha7 nicotinic acetylcholine receptor (α7nAChR) can modulate immune responses in both the periphery and the brain. The aims of the present study were to investigate α7nAChR expression in different brain regions and evaluate the potential effect of the selective α7nAChR agonist AR-R17779 on ischemia–reperfusion brain injury in mice. Droplet digital PCR (ddPCR) was used to evaluate the absolute expression of the gene encoding α7nAChR (Chrna7) in hippocampus, striatum, thalamus and cortex in adult, naïve mice. Mice subjected to transient middle cerebral artery occlusion (tMCAO) or sham surgery were treated with α7nAChR agonist AR-R17779 (12 mg/kg) or saline once daily for 5 days. Infarct size and microglial activation 7 days after tMCAO were analyzed using immunohistochemistry. Chrna7 expression was found in all analyzed brain regions in naïve mice with the highest expression in cortex and hippocampus. At sacrifice, white blood cell count was significantly decreased in AR-R17779 treated mice compared with saline controls in the sham groups, although, no effect was seen in the tMCAO groups. Brain injury and microglial activation were evident 7 days after tMCAO. However, no difference was found between mice treated with saline or AR-R17779. In conclusion, α7nAChR expression varies in different brain regions and, despite a decrease in white blood cells in sham mice receiving AR-R17779, this compound does not affect stroke-induced brain injury.

Adult neurogenesis, the production of newborn neurons from neural stem cells (NSCs) has been suggested to be decreased in patients with schizophrenia. A similar finding was observed in an animal model of schizophrenia, as indicated by decreased bromodeoxyuridine (BrdU) labelling cells in response to a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist. The antipsychotic drug clozapine was shown to counteract the observed decrease in BrdU-labelled cells in hippocampal dentate gyrus (DG). However, phenotypic determination by immunohistochemistry analysis could not reveal whether BrdU-positive cells were indeed NSCs. Using a previously established cell model for analysing NSC protection in vitro, we investigated a protective effect of clozapine on NSCs. Primary NSCs were isolated from the mouse subventricular zone (SVZ), we show that clozapine had a NSC protective activity alone, as evident by employing an ATP cell viability assay. In contrast, haloperidol did not show any NSC protective properties. Subsequently, cells were exposed to the non-competitive NMDA-receptor antagonist ketamine. Clozapine, but not haloperidol, had a NSC protective/anti-apoptotic activity against ketamine-induced cytotoxicity. The observed NSC protective activity of clozapine was associated with increased expression of the anti-apoptotic marker Bcl-2, decreased expression of the pro-apoptotic cleaved form of caspase-3 and associated with decreased expression of the autophagosome marker 1A/1B-light chain 3 (LC3-II). Collectively, our findings suggest that clozapine may have a protective/anti-apoptotic effect on NSCs, supporting previous in vivo observations, indicating a neurogenesis-promoting activity for clozapine. If the data are further confirmed in vivo, the results may encourage an expanded use of clozapine to restore impaired neurogenesis in schizophrenia.

The interplay between obesity and type 2 diabetes (T2D) in poststroke recovery is unclear. Moreover, the impact of glucose control during the chronic phase after stroke is undetermined. We investigated whether obesity-induced T2D impairs neurological recovery after stroke by using a clinically relevant experimental design. We also investigated the potential efficacy of two clinically used T2D drugs: the dipeptidyl peptidase 4 inhibitor linagliptin and the sulfonylurea glimepiride. We induced transient middle cerebral artery occlusion (tMCAO) in T2D/obese mice (after 7 months of high-fat diet [HFD]) and age-matched controls. After stroke, we replaced HFD with standard diet for 8 weeks to mimic the poststroke clinical situation. Linagliptin or glimepiride were administered daily from 3 days after tMCAO for 8 weeks. We assessed neurological recovery weekly by upper-limb grip strength. Brain damage, neuroinflammation, stroke-induced neurogenesis, and atrophy of parvalbumin-positive (PV+) interneurons were quantified by immunohistochemistry. T2D/obesity impaired poststroke neurological recovery in association with hyperglycemia, neuroinflammation, and atrophy of PV(+)interneurons. Both drugs counteracted these effects. In nondiabetic mice, only linagliptin accelerated recovery. These findings shed light on the interplay between obesity and T2D in stroke recovery. Moreover, they promote the use of rehabilitative strategies that are based on efficacious glycemia regulation, even if initiated days after stroke.

The nigrostriatal dopaminergic system (NDS) controls motor activity, and its impairment during type 2 diabetes (T2D) progression could increase Parkinson's disease risk in diabetics. If so, whether glycemia regulation prevents this impairment needs to be addressed. We investigated whether T2D impairs the NDS and whether dipeptidyl peptidase-4 inhibition (DPP-4i; a clinical strategy against T2D but also neuroprotective in animal models) prevents this effect, in middle-aged mice. Neither T2D (induced by 12 months of high-fat diet) nor aging (14 months) changed striatal dopamine content assessed by high-performance liquid chromatography. However, T2D reduced basal and amphetamine-stimulated striatal extracellular dopamine, assessed by microdialysis. Both the DPP-4i linagliptin and the sulfonylurea glimepiride (an antidiabetic comparator unrelated to DPP-4i) counteracted these effects. The functional T2D-induced effects did not correlate with NDS neuronal/glial alterations. However, aging itself affected striatal neurons/glia, and the glia effects were counteracted mainly by DPP-4i. These findings show NDS functional pathophysiology in T2D and suggest the preventive use of two unrelated anti-T2D drugs. Moreover, DPP-4i counteracted striatal age-related glial alterations suggesting striatal rejuvenation properties.