Post-stroke depression (PSD) is a common and debilitating complication that disproportionately affects women, yet the underlying risk factors remain incompletely understood. Hormonal fluctuations across a woman’s lifespan, including those naturally occurring during puberty, pregnancy, and menopause, as well as exposures to exogenous hormones, such as oral contraceptives, assisted reproductive technologies, and hormonal replacement therapies, profoundly influence neurobiological pathways, potentially modulating both stroke risk and subsequent depressive disorders. Female-specific or female-predominant patient factors, including polycystic ovary syndrome, migraine, autoimmune disease, and breast cancer may exacerbate susceptibility to depression after stroke. Behavioral factors, such as smoking, substance use, and stress, further interact with biological predispositions to impact PSD outcomes. Our review presents current evidence on the intersection of hormonal fluctuations, patient factors, and behavioral influences in shaping the stroke risk and manifestation of PSD in women. Addressing the intersecting influences on PSD offers a promising pathway to improve post-stroke mental health outcomes and enhance quality of life for women.

The global rise in nicotine-containing electronic cigarette (EC) use highlights the need to understand their impact on stroke outcomes. This study examined how EC exposure affects post-ischemic inflammation in adult Sprague-Dawley rats. Both sexes were exposed to air or EC vapor (5% nicotine Juul pods) for 16 nights, followed by transient middle cerebral artery occlusion (tMCAO; 90 min) or sham surgery. Animals were divided into two cohorts. In Cohort 1, RNA sequencing of ipsilateral cortex at 16 days post-tMCAO revealed 443 upregulated and 453 downregulated genes in males, and 537 upregulated and 578 downregulated genes in females (p<0.05). Differentially expressed genes in males were linked to membrane transport, signaling, and immune responses. In females, genes were enriched in pathways related to synaptic structure, cognition, proliferation, and genomic maintenance. In Cohort 2, microglial activation was analyzed 21 days post-tMCAO using Iba-1 immunostaining and Sholl analysis. EC-exposed females exhibited more de-ramified microglia, larger soma size, shorter branch length, and reduced morphological complexity compared to air-exposed controls. Current findings suggest that EC exposure exacerbates post-stroke neuroinflammation and transcriptomic dysregulation, particularly in females. Future studies should investigate whether withdrawal from EC reduces ischemic stroke severity and define the timeframe required for potential recovery.

Introduction: Rehabilitative physical therapy is essential for reducing stroke-related functional deficits; however, comorbidities may limit patient participation. Whole body vibration (WBV; 40 Hz) offers an exercise-like alternative. Our studies show that one month of post-stroke WBV reduces ischemic damage and improves motor and cognitive function in middle-aged rats. Notably, WBV significantly increased circulating irisin, a muscle-derived hormone. We hypothesize that post-stroke WBV modifies the cerebral transcriptome and irisin treatment improves stroke outcome in middle-aged female rats. Methods: Middle-aged Sprague-Dawley rats were randomized to sham or transient middle cerebral artery occlusion (tMCAO; 90 min) surgery and divided into two cohorts. A cohort received either no-WBV (steady platform) or WBV (platform vibrating at 40 Hz) for 15 minutes twice a day for a week. Cortical tissue was then collected for RNA sequencing (RNAseq) and gene enrichment analysis. The second cohort received either saline or irisin (PeproTech, 0.2 µg/g BW) treatment at 4.5 hours post-tMCAO and then once a week for a month. At 21 days post-tMCAO, rats were assessed for cognitive deficits via the Morris water maze. At 1-month post-tMCAO, brains were collected for histological analysis. Results: RNAseq revealed significant (p<0.05) differential expression of 581 genes in the cortex due to WBV. Specifically, there was downregulation (log 2 (fold change) = -2.9; p= 0.03943) of Calcium Voltage-Gated Channel Auxiliary Subunit Gamma 7 ( Cacng7 ) and calcium-release channel activity (GO:0015278), which are both implicated in excitotoxicity following stroke. The expression of Vacuolar Protein Sorting-Associated Protein 37C ( Vps37c ), a component of an endosomal sorting complex that mediates apoptosis, was also downregulated (log 2 (fold change) = -7.1; p= 0.01888). In our second cohort, rats treated with irisin for 1-month post-tMCAO, as compared to saline, demonstrated significantly (p<0.05) reduced cognitive deficits in spatial learning (hidden platform) and memory (probe trial). Additionally, irisin treatment significantly (p<0.05) reduced infarct damage at 1-month post-tMCAO. Conclusion: Post-stroke WBV increases the expression of genes responsible for ischemic tolerance and irisin treatment improves cognitive outcomes in middle-aged rats. Future studies are needed to understand the underlying mechanism(s) responsible for irisin-conferred ischemic protection.

BACKGROUND:Significant cognitive impairment follows cardiac arrest, yet few interventions restore memory. We previously demonstrated that physical exercise (PE) after asphyxial cardiac arrest (ACA) mitigates memory deficits and cell loss in the septal nuclei, but not in the hippocampus in rats. Given the critical role of the septum in modulating hippocampal theta oscillations, essential for memory, we hypothesize that PE preserves memory by safeguarding septal pacemaker neurons and septo-hippocampal theta activity. METHODS:Adult male and female rats underwent 8 minutes of ACA or sham surgery and were randomly assigned to 5 days of treadmill running PE or sedentary conditions. Long- and short-term memory were assessed using fear conditioning and Y-maze tests. Immunohistochemistry quantified septal cholinergic and gamma-aminobutyric acid-ergic neurons. Local field potential recordings evaluated oscillatory activity across the septo-hippocampal network. RESULTS:ACA induced persistent deficits in memory and disrupted theta oscillations throughout the septum and cornu ammonis 1 (CA1) laminae. These changes were accompanied by selective loss of cholinergic and gamma-aminobutyric acid-ergic septal neurons. PE markedly improved cognitive performance and restored theta power across the septo-hippocampal axis. Only cholinergic, not gamma-aminobutyric acid-ergic, neurons were preserved after PE. All effects were consistent across sexes. Importantly, enhancements in CA1 theta power closely tracked behavioral recovery, implying that reestablishment of cholinergic-driven network dynamics plays a central role in memory restoration. CONCLUSIONS:This study is the first to directly implicate PE-induced cholinergic neuron preservation in the reengagement of septo-hippocampal circuitry and cognitive recovery post cardiac arrest. Rather than relying on hippocampal cell survival, the observed memory improvements appear to stem from reinstated interregional theta synchrony. These findings define a novel mechanistic pathway for promoting functional recovery via targeted circuit-level rehabilitation after ischemic brain injury.

The rising use of nicotine-containing electronic cigarettes (EC) underscores the need to understand their impact on stroke outcomes. Our previous work showed that 16 days of EC exposure worsened post-stroke cognitive decline in young rats of both sexes, likely through altered brain energy metabolism. However, its downstream effects on neurotransmitters (NT) remain unclear. This study investigates how EC exposure affects NT metabolism and its consequences on ischemic injury. Adult Sprague-Dawley rats were exposed to air or EC for 16 nights. One cohort underwent global metabolomic profiling of cortical tissue. A second cohort received transient middle cerebral artery occlusion (tMCAO; 90 min) or sham surgery, then survived 1 day before cortical samples were collected for tryptophan hydroxylase (TPH) and tyrosine hydroxylase (TH) protein analysis. A third cohort underwent the same exposures but survived for 21 days, after which brains were collected for immunohistochemical analysis. Three brain sections per animal were labeled with anti-TPH or anti-TH antibodies to visualize TPH-positive and TH-positive neurons in the dorsal raphe nucleus (DRN), ventral tegmental area (VTA), and substantia nigra (SN). Neuron counts were estimated using a brightfield stereoscope and StereoInvestigator software. EC-exposed females showed reduced post-stroke neuronal survival across all brain regions compared to air-exposed females; this effect was not observed in males. Metabolomics revealed significant (p ≤ 0.05) increases in phenylalanine and tryptophan metabolites, along with mixed changes in tyrosine metabolites. A marked reduction in TH- and TPH-positive neurons was also observed post-tMCAO in EC-exposed females. These NT alterations, more prominent in females, may contribute to EC-related cognitive decline and depressive symptoms, underscoring the need for further investigation into EC's impact on ischemic brain injury.

Introduction: The rise in popularity of nicotine-containing electronic cigarettes (ECs) globally necessitates a deeper understanding of their effects on stroke outcomes. This study investigates the influence of EC exposure on post-ischemic inflammation. Methods: Adult Sprague-Dawley rats of both sexes were randomly assigned to either air or EC vapor exposure (5% nicotine Juul pods) for 16 nights, followed by transient middle cerebral artery occlusion (tMCAO; 90 minutes) or sham surgery. Post-surgery, animals were divided into two cohorts. In the first cohort, cortical brain tissue was collected 24 hours after tMCAO or sham surgery for Western blot analysis of inflammasome proteins, including Caspase-1, Interleukin-1β (IL-1β), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and gasdermin-D (GSDMD). The second cohort was sacrificed 21 days post-tMCAO for immunohistochemical analysis of microglial marker ionized calcium-binding adapter molecule-1 (Iba-1). De-ramified microglia were quantified across three serial coronal sections (10 μm) using the optical fractionator probe in StereoInvestigator software, with a counting frame of 100x100 μm and approximately 40 sampling sites per section. Microglial morphology and Sholl analysis were performed by capturing three cortical images per slide, each containing at least three microglia, and across three slides per subject, resulting in 18 images for peri-infarct and contralateral areas. Analysis was conducted using ImageJ software. Results: Western blot analysis revealed a significant increase in Caspase-1 and ASC protein levels in the ipsilateral cortex of EC-exposed female rats compared to males after tMCAO (p<0.05). Quantification of Iba-1 indicated an increase in de-ramified microglia in the cortex of EC-exposed female rats as compared to air-exposed after tMCAO, potentially exacerbating post-stroke infarction. Microglial morphology analysis showed increased cell soma size and decreased branch length in EC-exposed female rats. Sholl analysis demonstrated reduced microglial complexity in EC-exposed group as compared to air-exposed after tMCAO, with a smaller area under the curve and fewer peak intersections in the cortex. Conclusion: EC exposure exacerbates stroke-induced inflammation and cognitive deficits in female rats. Future research should explore whether EC withdrawal mitigates ischemic severity and determine the necessary duration of withdrawal for potential recovery.

Introduction: Menopause increases the risk and severity of ischemic stroke (IS), while endogenous 17β-estradiol (E2) naturally protects premenopausal women against IS. The female sex hormone E2 is a potent neuro- and cognitive-protective agent. Studies have shown that periodic E2 or estrogen receptor subtype-beta (ER-β) agonist pre-treatments every 48 hours before an ischemic episode ameliorated ischemic brain damage in young ovariectomized or reproductively senescent (RS) aged female rats. The current study investigates the underlying mechanism of ER-β agonist-mediated neuroprotection. Methods: Retired breeder (9–10 months) Sprague–Dawley female rats were considered RS after remaining in constant diestrus phase for more than a month. The RS rats were exposed to transient middle cerebral artery occlusion (tMCAO; 90 mins) and treated with either ER-β agonist (beta 2, 3-bis(4-hydroxyphenyl) propionitrile; DPN; 1 mg/kg; s.c.) or DMSO vehicle at 4.5 hours after induction of tMCAO. Subsequently, rats were treated with either ER-β agonist or DMSO vehicle every 48 hours (48-h) for ten injections. Forty-eight hours after the last treatment, animals were tested for cognitive deficits via the Morris water maze. At 1-month post-tMCAO, brains were collected for histopathological analysis. A second cohort of RS rats underwent DPN or DMSO treatment for a month; 48-h after last injection, brains were collected for unbiased global metabolomic analysis (conducted by Metabolon Inc.). The metabolomic study was complemented with western blot analysis and enzyme activity measurements of key altered pathways. Results: Data showed significant (p<0.05) decreases in glucose-6-phosphate and increases in 5-phosphyribosyl diphosphate, UDP-galactose, and N-acetylglucoseamine-6-phosphate in the brain of DPN-treated RS female rats as compared to DMSO-treated controls. DPN treatment also changes the enzymatic activity of glycolytic rate limiting enzyme hexokinase. Metabolomics data also showed significant increase in choline and arginine levels in the brain of DPN-treated RS female rats as compared to DMSO-treated controls. Conclusion: The observed changes in glycolytic and amino acid pathway metabolites could enhance brain energy metabolism and increase choline availability, potentially contributing to the improved post-stroke cognitive outcomes in RS rats.

Introduction: About 65% of women in their reproductive years use contraception, with combined oral contraceptives (OC) being among the most popular. OC, which contain estrogen and progestin, are linked to a higher risk of stroke, particularly in the first year of use. This study aims to explore the mechanisms and effects of OC exposure on stroke outcomes. Methods: Adult female Sprague-Dawley rats (n= 6-8/group) were randomly assigned to receive either a placebo or OC by oral gavage for 12-14 estrous cycles. The animals were divided into two cohorts following treatment. In the first cohort, brain tissue was harvested to obtain an unbiased global metabolomic profile (Metabolon Inc.) This metabolomic analysis was supplemented with western blotting and enzyme activity measurements of key altered pathways. The second cohort underwent either transient middle cerebral artery occlusion (tMCAO; 90 min) or sham surgery and was observed for 21 days. During this post-tMCAO/sham period, cognition was assessed using the Morris water maze, followed by brain collection for histopathological and immunohistochemical analysis. Results: OC exposure significantly increased infarct volume and impaired cognition in rats compared to the placebo group. Metabolomic analysis revealed significant alterations in sphingolipid metabolism, particularly an increase in sphingosine 1-phosphate (S1P) levels (p<0.05) in OC-exposed brains. A crucial enzyme for generation of S1P is Sphingosine Kinase 2 (SphK2) in the brain. Western blot analysis confirmed significant increases in SphK2 protein levels upon OC exposure. Additionally, OC exposure led to a significant decrease in sphingosine 1-phosphate lyase protein levels, responsible for S1P degradation. We also observed a notable increase in S1P receptor 3 protein levels, which plays a key role in inflammation. Therefore, microglial activation was quantified in the brain following tMCAO. Conclusion: The data indicate that OC exposure worsens ischemic outcomes by altering S1P metabolism. Future studies are needed to better understand S1P's role in OC-induced ischemic outcomes, which could help identify potential therapeutic targets.

BACKGROUND:Irisin, a myokine cleaved from its precursor FNDC5 (fibronectin type III domain-containing protein 5) following exercise or low-frequency whole-body vibration, regulates energy metabolism and insulin sensitivity. This study examines irisin's therapeutic potential in stroke in rats. METHODS:Adult Sprague-Dawley rats of both sexes underwent transient middle cerebral artery occlusion (90 minutes) or sham surgery. After 4.5 hours, they were randomized to receive saline or irisin treatment (0.1, 0.2, and 0.8 μg/g body weight). Infarct volume was quantified 1 day after transient middle cerebral artery occlusion using 2,3,5-triphenyltetrazolium chloride staining. In a subsequent study, reproductively senescent female rats received either saline or 0.2 μg/g body weight irisin at 4.5 hours post-transient middle cerebral artery occlusion, followed by weekly treatments for a month. Sensorimotor and cognitive functions were assessed using the cylinder test and Morris water maze. Ipsilateral cortical tissue was collected from a subset of the reproductive senescence rats following 2 weeks of treatment for RNA sequencing and real-time quantitative polymerase chain reaction analysis. RESULTS:Irisin (0.2 μg/g) significantly reduced infarct volume by 50% in females and 36% in males compared with their respective saline groups. In reproductive senescence females, irisin treatment for a month improved contralateral limb use by day 7 and enhanced spatial learning in the Morris water maze, reducing latency to find the hidden platform on the fourth day of testing (16.5 sec versus saline; P<0.05) and increasing time spent in the target quadrant during the probe trial (9.3 sec versus saline; P<0.05). Irisin therapy significantly altered cortical gene expression, with 332 genes upregulated and 136 downregulated. Gene ontology analysis revealed genes linked to the extracellular matrix were significantly upregulated, which was confirmed by increased expression of the cell-surface integrin αVβ5, known to interact with irisin. CONCLUSIONS:Post-transient middle cerebral artery occlusionirisin therapy modulates the transcriptome, enhancing motor and cognitive function while protecting against ischemic brain damage in middle-aged female rats.

Navigating menopause involves traversing a complex terrain of hormonal changes that extend far beyond reproductive consequences. Menopausal transition is characterized by a decrease in estradiol-17β (E2), and the impact of menopause resonates not only in the reproductive system but also through the central nervous system, musculoskeletal, and gastrointestinal domains. As women undergo menopausal transition, they become more susceptible to frailty, amplifying the risk and severity of injuries, including traumatic brain injury (TBI). Menopause triggers a cascade of changes leading to a decline in muscle mass, accompanied by diminished tone and excitability, thereby restricting the availability of irisin, a crucial hormone derived from muscles. Concurrently, bone mass undergoes reduction, culminating in the onset of osteoporosis and altering the dynamics of osteocalcin, a hormone originating from bones. The diminishing levels of E2 during menopause extend their influence on the gut microbiota, resulting in a reduction in the availability of tyrosine, tryptophan, and serotonin metabolites, affecting neurotransmitter synthesis and function. Understanding the interplay between menopause, frailty, E2 decline, and the intricate metabolisms of bone, gut, and muscle is imperative when unraveling the nuances of TBI after menopause. The current review underscores the significance of accounting for menopause-associated frailty in the incidence and consequences of TBI. The review also explores potential mechanisms to enhance gut, bone, and muscle health in menopausal women, aiming to mitigate frailty and improve TBI outcomes.

Stroke is a serious complication of diabetes. Intensive treatment of diabetes increases the risk of recurrent hypoglycemia (RH). Hypoglycemia exposure causes prothrombotic effects. Earlier, we demonstrated that exposure to single hypoglycemia (SH), 5-day RH (once every day), and twice-a-week RH for 6 weeks increases stroke risk in male insulin-treated diabetic (ITD) rats. In the present study, we determined the effect of SH and RH on stroke risk/thrombosis in female rats. Streptozotocin diabetic female rats were treated for hyperglycemia using insulin pellets (Figure A). Rats were randomly assigned to either hyperinsulinemic euglycemia (ITD+RH+Glucose, control) or hyperinsulinemic hypoglycemia (ITD+RH) groups (3 h duration) (Figure B). Separate groups tested the effect of SH, RH for 5 days, or RH for 6 weeks. Based on the results of the male studies, stroke risk after SH, 5-day RH, and 6-week RH were assessed on days 1, 7, and 3 post-last hypoglycemia, respectively. Groups were balanced (confirmed by Chi square test) in terms of the proportion of animals at different stages of the estrous cycle. To assess the risk of stroke, the carotid artery and jugular vein were linked with a shunt containing a suture, and the weight of the clot accumulated on the suture following 15 min of blood flow was quantified as a measure of stroke risk/thrombosis. The clot weight in the SH-exposed ITD group was significantly higher by 47% (22±3 mg, n=9, p<0.05) when compared to its respective control (15±1 mg, n=8). The clot weight determined 7 days after the 5-day ITD+RH group (18±1 mg, n=7) was significantly (p<0.05) higher than its control group (15±1 mg, n=9). The clot weight in the 6-week ITD+RH group was significantly higher by 47% (20±2 mg, n=9, p<0.01) when compared to its control (14±1 mg, n=7) (Figure C). Our results show that similar to male rats, SH and RH increase stroke risk in female ITD rats. We are currently evaluating the underlying mechanisms. Acknowledgment: NIH (NS122808).

BACKGROUND: Nicotine-containing electronic cigarette (EC) vaping has become popular worldwide, and our understanding of the effects of vaping on stroke outcomes is elusive. Using a rat model of transient middle cerebral artery occlusion, the current exploratory study aims to evaluate the sex-dependent effects of EC exposure on brain energy metabolism and stroke outcomes. METHODS: Adult Sprague-Dawley rats of both sexes were randomly assigned to air/EC vapor (5% nicotine Juul pods) exposure for 16 nights, followed by randomization into 3 cohorts. The first cohort underwent exposure to air/EC preceding randomization to transient middle cerebral artery occlusion (90 minutes) or sham surgery, followed by survival for 21 days. During the survival period, rats underwent sensorimotor and Morris water maze testing. Subsequently, brains were collected for histopathology. A second cohort was exposed to air/EC after which brains were collected for unbiased metabolomics analysis. The third cohort of animals was exposed to air/EC and received transient middle cerebral artery occlusion/sham surgery, and brain tissue was collected 24 hours later for biochemical analysis. RESULTS: In females, EC significantly increased ( P <0.05) infarct volumes by 94% as compared with air-exposed rats, 165±50 mm 3 in EC-exposed rats, and 85±29 mm 3 in air-exposed rats, respectively, while in males such a difference was not apparent. Morris water maze data showed significant deficits in spatial learning and working memory in the EC sham or transient middle cerebral artery occlusion groups compared with the respective air groups in rats of both sexes ( P <0.05). Thirty-two metabolites of carbohydrate, glycolysis, tricarboxylic acid cycle, and lipid metabolism were significantly altered ( P ≤0.05) due to EC, 23 of which were specific for females. Steady-state protein levels of hexokinase significantly decreased ( P <0.05) in EC-exposed females; however, these changes were not seen in males. CONCLUSIONS: Even brief EC exposure over 2 weeks impacts brain energy metabolism, exacerbates infarction, and worsens poststroke cognitive deficits in working memory more in female than male rats.

Low-frequency whole body vibration (WBV; 40Hz) therapy after stroke reduces ischemic brain damage, motor, and cognitive deficits in middle-aged rats of both sexes. However, the underlying mechanisms responsible for WBV induced ischemic protections remain elusive. In the current study, we hypothesize that post-stroke WBV initiates transcriptional reprogramming in the cortex of middle-aged female rats which is responsible for the observed reduced stroke consequences. Middle-aged female Sprague-Dawley rats that remained in constant diestrus (reproductively senescent) were randomized to either sham or transient middle cerebral artery occlusion (tMCAO; 90 min) surgery. A day after induction of tMCAO, animals received either WBV or no-WBV treatment for 15 minutes twice a day for five days for a week. Post-treatment, cortical tissue was analyzed for gene expression using RNA sequencing (RNAseq) and gene enrichment analysis via Enrichr. The RNAseq data analysis revealed significant changes in gene expression due to WBV therapy and the differentially expressed genes are involved in variety of biological processes like neurogenesis, angiogenesis, excitotoxicity, and cell death. Specifically, observed significant up-regulation of 116 and down-regulation of 258 genes after WBV in tMCAO exposed rats as compared to the no-WBV group. The observed transcriptional reprogramming will identify the possible mechanism(s) responsible for post-stroke WBV conferred ischemic protection and future studies will be needed to confirm the role of the genes identified in the current study.

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Introduction: Smoking is a preventable risk factor for stroke and battery-operated nicotine delivery systems known as electronic cigarettes (EC) are popular. EC vapes aerosolize a mix of nicotine and chemicals forming harmful toxicants such as formaldehyde hemiacetal. Our understanding about effects of EC vaping on stroke outcome is limited. This study investigated effects of EC on global metabolic signature and stroke outcome in animals of both sexes. Methods: Sprague-Dawley rats (2-3 months old; n=8) of both sexes were randomly assigned either to air or EC vapor (5% nicotine Juul pods) exposure using the EcigAero-TM Aerosol Exposure Apparatus. Rats were exposed to air/EC for 16 nights. Per night, rats were exposed to 16 episodes of EC vapor. Each episode consisted of 2 seconds of Juul puffs followed by 8 seconds of air over the period of 8 minutes. After 16 days, the rats were divided into two cohorts. The first cohort of rats exposed to EC/Air was tested for cognitive capacities using the Morris water maze (WM) followed by brain collection for unbiased metabolomic (Metabolon Inc.) or Western blot analysis. The second cohort of rats exposed to EC/Air was subjected to transient middle cerebral artery occlusion (tMCAO; 90 min) or sham surgery and survived for 15-21 days. During the post-tMCAO survival, rats were tested for cognition using WM followed by brain collection for histopathological analysis. Results: Metabolomic analysis indicated that EC exposure resulted in significant increases (p≤0.05) in phenylalanine and tryptophan metabolites, and both increases (p≤0.05) and decreases (p≤0.05) in histamine and tyrosine metabolites in the brains of female and male rats. Western blotting of rate-limiting enzymes in respective NT pathways corroborated the metabolomic data. Behavioral testing indicated worsened cognitive outcome in EC groups compared to air groups in rats of both sexes. Conclusion: EC vape exposure, even for as short as 2 weeks, impacts the metabolism of NT, induces cognitive deficits and worsens stroke outcomes in young male and female rats. Future studies investigating the impact of EC withdrawal on NT metabolism are needed to understand how long the deleterious effects of EC vaping persist in the brain.

Naturally occurring life stages in women are associated with changes in the milieu of endogenous ovarian hormones. Women of childbearing age may be exposed to exogenous ovarian hormone(s) because of their use of varying combinations of estrogen and progesterone hormones-containing oral contraceptives (OC; also known as "the pill"). If women have central nervous system (CNS) injury such as spinal cord injury (SCI) and traumatic brain injury (TBI) during their childbearing age, they are likely to retain their reproductive capabilities and may use OC. Many deleterious side effects of long-term OC use have been reported, such as aberrant blood clotting and endothelial dysfunction that consequently increase the risk of myocardial infarction, venous thromboembolism, and ischemic brain injury. Although controversial, studies have suggested that OC use is associated with neuropsychiatric ramifications, including uncontrollable mood swings and poorer cognitive performance. Our understanding about how the combination of endogenous hormones and OC-conferred exogenous hormones affect outcomes after CNS injuries remains limited. Therefore, understanding the impact of OC use on CNS injury outcomes needs further investigation to reveal underlying mechanisms, promote reporting in clinical or epidemiological studies, and raise awareness of possible compounded consequences. The goal of the current review is to discuss the impacts of CNS injury on endogenous ovarian hormones and vice-versa, as well as the putative consequences of exogenous ovarian hormones (OC) on the CNS to identify potential gaps in our knowledge to consider for future laboratory, epidemiological, and clinical studies.

Women have a higher risk of having an ischemic stroke and increased cognitive decline after stroke as compared to men. The female sex hormone 17 beta-estradiol (E2) is a potent neuro- and cognitive-protective agent. Periodic E2 or estrogen receptor subtype-beta (ER-beta) agonist pre-treatments every 48 h before an ischemic episode ameliorated ischemic brain damage in young ovariectomized or reproductively senescent (RS) aged female rats. The current study aims to investigate the efficacy of post-stroke ER-beta agonist treatments in reducing ischemic brain damage and cognitive deficits in RS female rats. Retired breeder (9-10 months) Sprague-Dawley female rats were considered RS after remaining in constant diestrus phase for more than a month. The RS rats were exposed to transient middle cerebral artery occlusion (tMCAO) for 90 min and treated with either ER-beta agonist (beta 2, 3-bis(4-hydroxyphenyl) propionitrile; DPN; 1 mg/kg; s.c.) or DMSO vehicle at 4.5 h after induction of tMCAO. Subsequently, rats were treated with either ER-beta agonist or DMSO vehicle every 48 h for ten injections. Forty-eight hours after the last treatment, animals were tested for contextual fear conditioning to measure post-stroke cognitive outcome. Neurobehavioral testing, infarct volume quantification, and hippocampal neuronal survival were employed to determine severity of stroke. Periodic post-stroke ER-beta agonist treatment reduced infarct volume, improved recovery of cognitive capacity by increasing freezing in contextual fear conditioning, and decreased hippocampal neuronal death in RS female rats. These data suggest that periodic post-stroke ER-beta agonist treatment to reduce stroke severity and improve post-stroke cognitive outcome in menopausal women has potential for future clinical investigation.

Abstract The safety and benefit of intra-arterial (IA) allogeneic Mesenchymal Stem Cells (MSCs) administered within 1-2 days of stroke in rodent models hold transformative potential for treating acute ischemic stroke (AIS). However, the lack of large animal studies of this approach is a significant gap in predicting success in human clinical trials, given the small size of the rodent brain and arterial vasculature and the lower white-to-gray-matter ratio. Another critical gap is the inability to extrapolate IA MSC dose ranges of MSCs and their therapeutic index from rodent models in a predictable manner. Here we employed an endovascular canine stroke model to evaluate the safety and efficacy of escalating IA doses of allogeneic MSCs at 10, and 40 million (m), and 80m MSCs versus phosphate buffer saline (PBS) controls. The IA MSC group showed safety on the primary endpoints of no worsening of neurological deficit and no new ischemia on imaging up to 40m dose. There was a significantly higher improvement in the treatment group in primary efficacy endpoints of neurological function and reduction in infarct volume on MRI and on the secondary endpoint of recovery of corticospinal tract caliber and fractional anisotropy on DTI compared to controls at 15- and 30-days post-stroke. A significant increase in neuronal survival was also seen in the IA MSC group vs the PBS control. Upon further dose escalation to 80m, there was worsened neurological score and worsened infarct at 4 days post-injection. Thus this study shows the safety and efficacy of IA MSCs over a dose range of 10-40m in a large animal model and its therapeutic index. In conclusion, these findings suggest a high translational success of IA allogeneic MSCs for AIS and provide critical information for the design of future clinical trials.