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Singh T, Ramakrishnan S, Wu X, Reddy DS. Sex Differences in Organophosphate Model of Benzodiazepine-Refractory Status Epilepticus and Neuronal Damage. J Pharmacol Exp Ther 2024; 388:313-324. [PMID: 37770202 PMCID: PMC10801723 DOI: 10.1124/jpet.123.001747] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 10/03/2023] Open
Abstract
Sex differences are common in human epilepsy. Although men are more susceptible to seizure than women, the mechanisms underlying sex-specific vulnerabilities to seizure are unclear. The organophosphate (OP) diisopropylfluorophosphate (DFP) is known to cause neurotoxicity and status epilepticus (SE), a serious neurologic condition that causes prolonged seizures and brain damage. Current therapies for OP poisoning and SE do not consider neuronal variations between male and female brains. Therefore, we investigated sex-dependent differences in electrographic seizure activity and neuronal injury using the DFP model of refractory SE in rats. Electroencephalogram recordings were used to monitor DFP-induced SE, and the extent of brain injury was determined using fluoro-jade-B staining to detect cellular necrosis. After DFP exposure, we observed striking sex-dependent differences in SE and seizure activity patterns as well as protective responses to midazolam treatment. Following acute DFP exposure, male animals displayed more severe SE with intense epileptiform spiking and greater mortality than females. In contrast, we observed significantly more injured cells and cellular necrosis in the hippocampus and other brain regions in females than in males. We also observed extensive neuronal injury in the somatosensory cortex of males. The anticonvulsant effect of midazolam against SE was limited in this model and found to be similar in males and females. However, unlike males, females exhibited substantially more protection against neuronal damage after midazolam treatment. Overall, these results demonstrate significant sex-dependent differences in DFP-induced refractory SE and neuronal damage patterns, suggesting that it may be possible to develop sex-specific neuroprotective strategies for OP intoxication and refractory SE. SIGNIFICANCE STATEMENT: Sex-dependent differences in neurotoxicity and status epilepticus (SE) are key biological variables after organophosphate (OP) exposure. Here, we investigated sex-dependent differences in SE and brain injury after acute diisopropylfluorophosphate exposure. Male rats had more severe SE and less survival than females, while females had more neuronal damage. Females had more neuroprotection to midazolam than males, while both sexes had similar but partial anticonvulsant effects. These findings suggest that a sex-specific therapeutic approach may prevent neurological complications of OP-induced SE.
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Affiliation(s)
- Tanveer Singh
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Sreevidhya Ramakrishnan
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Xin Wu
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
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Putra M, Vasanthi SS, Rao NS, Meyer C, Van Otterloo M, Thangi L, Thedens DR, Kannurpatti SS, Thippeswamy T. Inhibiting Inducible Nitric Oxide Synthase with 1400W Reduces Soman (GD)-Induced Ferroptosis in Long-Term Epilepsy-Associated Neuropathology: Structural and Functional Magnetic Resonance Imaging Correlations with Neurobehavior and Brain Pathology. J Pharmacol Exp Ther 2024; 388:724-738. [PMID: 38129129 PMCID: PMC10801728 DOI: 10.1124/jpet.123.001929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/23/2023] Open
Abstract
Organophosphate (OP) nerve agent (OPNA) intoxication leads to long-term brain dysfunctions. The ineffectiveness of current treatments for OPNA intoxication prompts a quest for the investigation of the mechanism and an alternative effective therapeutic approach. Our previous studies on 1400W, a highly selective inducible nitric oxide synthase (iNOS) inhibitor, showed improvement in epilepsy and seizure-induced brain pathology in rat models of kainate and OP intoxication. In this study, magnetic resonance imaging (MRI) modalities, behavioral outcomes, and biomarkers were comprehensively investigated for brain abnormalities following soman (GD) intoxication in a rat model. T1 and T2 MRI robustly identified pathologic microchanges in brain structures associated with GD toxicity, and 1400W suppressed those aberrant alterations. Moreover, functional network reduction was evident in the cortex, hippocampus, and thalamus after GD exposure, and 1400W rescued the losses except in the thalamus. Behavioral tests showed protection by 1400W against GD-induced memory dysfunction, which also correlated with the extent of brain pathology observed in structural and functional MRIs. GD exposure upregulated iron-laden glial cells and ferritin levels in the brain and serum, 1400W decreased ferritin levels in the epileptic foci in the brain but not in the serum. The levels of brain ferritin also correlated with MRI parameters. Further, 1400W mitigated the overproduction of nitroxidative markers after GD exposure. Overall, this study provides direct evidence for the relationships of structural and functional MRI modalities with behavioral and molecular abnormalities following GD exposure and the neuroprotective effect of an iNOS inhibitor, 1400W. SIGNIFICANT STATEMENT: Our studies demonstrate the MRI microchanges in the brain following GD toxicity, which strongly correlate with neurobehavioral performances and iron homeostasis. The inhibition of iNOS with 1400W mitigates GD-induced cognitive decline, iron dysregulation, and aberrant brain MRI findings.
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Affiliation(s)
- Marson Putra
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Suraj S Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Nikhil S Rao
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Christina Meyer
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Madison Van Otterloo
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Lal Thangi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Daniel R Thedens
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Sridhar S Kannurpatti
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa (M.P., S.S.V., N.S.R., C.M., M.V.O., L.T., T.T.); Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa (D.R.T.); and Department of Radiology, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, New Jersey (S.S.K.)
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Bernardino PN, Luo AS, Andrew PM, Unkel CM, Gonzalez MI, Gelli A, Lein PJ. Evidence Implicating Blood-Brain Barrier Impairment in the Pathogenesis of Acquired Epilepsy following Acute Organophosphate Intoxication. J Pharmacol Exp Ther 2024; 388:301-312. [PMID: 37827702 PMCID: PMC10801776 DOI: 10.1124/jpet.123.001836] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 09/14/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023] Open
Abstract
Organophosphate (OP) poisoning can trigger cholinergic crisis, a life-threatening toxidrome that includes seizures and status epilepticus. These acute toxic responses are associated with persistent neuroinflammation and spontaneous recurrent seizures (SRS), also known as acquired epilepsy. Blood-brain barrier (BBB) impairment has recently been proposed as a pathogenic mechanism linking acute OP intoxication to chronic adverse neurologic outcomes. In this review, we briefly describe the cellular and molecular components of the BBB, review evidence of altered BBB integrity following acute OP intoxication, and discuss potential mechanisms by which acute OP intoxication may promote BBB dysfunction. We highlight the complex interplay between neuroinflammation and BBB dysfunction that suggests a positive feedforward interaction. Lastly, we examine research from diverse models and disease states that suggest mechanisms by which loss of BBB integrity may contribute to epileptogenic processes. Collectively, the literature identifies BBB impairment as a convergent mechanism of neurologic disease and justifies further mechanistic research into how acute OP intoxication causes BBB impairment and its role in the pathogenesis of SRS and potentially other long-term neurologic sequelae. Such research is critical for evaluating BBB stabilization as a neuroprotective strategy for mitigating OP-induced epilepsy and possibly seizure disorders of other etiologies. SIGNIFICANCE STATEMENT: Clinical and preclinical studies support a link between blood-brain barrier (BBB) dysfunction and epileptogenesis; however, a causal relationship has been difficult to prove. Mechanistic studies to delineate relationships between BBB dysfunction and epilepsy may provide novel insights into BBB stabilization as a neuroprotective strategy for mitigating epilepsy resulting from acute organophosphate (OP) intoxication and non-OP causes and potentially other adverse neurological conditions associated with acute OP intoxication, such as cognitive impairment.
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Affiliation(s)
- Pedro N Bernardino
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Audrey S Luo
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Peter M Andrew
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Chelsea M Unkel
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Marco I Gonzalez
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Angie Gelli
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, California (P.N.B., A.S.L., P.M.A., C.M.U., P.J.L.); Department of Neurology, University of California, Davis, School of Medicine, Sacramento, California (M.I.G.); and Department of Pharmacology, University of California, Davis, School of Medicine, Davis, California (A.G.)
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4
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Blair RE, Hawkins E, Pinchbeck LR, DeLorenzo RJ, Deshpande LS. Chronic Epilepsy and Mossy Fiber Sprouting Following Organophosphate-Induced Status Epilepticus in Rats. J Pharmacol Exp Ther 2024; 388:325-332. [PMID: 37643794 PMCID: PMC10801751 DOI: 10.1124/jpet.123.001739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/20/2023] [Accepted: 07/24/2023] [Indexed: 08/31/2023] Open
Abstract
Organophosphate (OP) compounds are highly toxic and include pesticides and chemical warfare nerve agents. OP exposure inhibits the acetylcholinesterase enzyme, causing cholinergic overstimulation that can evolve into status epilepticus (SE) and produce lethality. Furthermore, OP-induced SE survival is associated with mood and memory dysfunction and spontaneous recurrent seizures (SRS). In male Sprague-Dawley rats, we assessed hippocampal pathology and chronic SRS following SE induced by administration of OP agents paraoxon (2 mg/kg, s.c.), diisopropyl fluorophosphate (4 mg/kg, s.c.), or O-isopropyl methylphosphonofluoridate (GB; sarin) (2 mg/kg, s.c.), immediately followed by atropine and 2-PAM. At 1-hour post-OP-induced SE onset, midazolam was administered to control SE. Approximately 6 months after OP-induced SE, SRS were evaluated using video and electroencephalography monitoring. Histopathology was conducted using hematoxylin and eosin (H&E), while silver sulfide (Timm) staining was used to assess mossy fiber sprouting (MFS). Across all the OP agents, over 60% of rats that survived OP-induced SE developed chronic SRS. H&E staining revealed a significant hippocampal neuronal loss, while Timm staining revealed extensive MFS within the inner molecular region of the dentate gyrus. This study demonstrates that OP-induced SE is associated with hippocampal neuronal loss, extensive MFS, and the development of SRS, all hallmarks of chronic epilepsy. SIGNIFICANCE STATEMENT: Models of organophosphate (OP)-induced SE offer a unique resource to identify molecular mechanisms contributing to neuropathology and the development of chronic OP morbidities. These models could allow the screening of targeted therapeutics for efficacious treatment strategies for OP toxicities.
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Affiliation(s)
- Robert E Blair
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Elisa Hawkins
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Lauren R Pinchbeck
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Robert J DeLorenzo
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Laxmikant S Deshpande
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
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Rao NS, Putra M, Meyer C, Almanza A, Thippeswamy T. The effects of Src tyrosine kinase inhibitor, saracatinib, on the markers of epileptogenesis in a mixed-sex cohort of adult rats in the kainic acid model of epilepsy. Front Mol Neurosci 2023; 16:1294514. [PMID: 38025259 PMCID: PMC10665569 DOI: 10.3389/fnmol.2023.1294514] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 10/25/2023] [Indexed: 12/01/2023] Open
Abstract
Neurodegeneration and neuroinflammation are key processes of epileptogenesis in temporal lobe epilepsy (TLE). A considerable number (∼30%) of patients with epilepsy are resistant to currently available antiseizure drugs and thus there is a need to develop adjunct therapies to modify disease progression. A vast majority of interventional strategies to treat TLE have utilized males which limits the translational nature of the studies. In this study, we investigated the effects of repeated low-dose kainic acid (KA) injection on the initial status epilepticus (SE) and the effects of Src kinase inhibitor, saracatinib (SAR/AZD0530; 20 mg/kg, oral, daily for 7 days), in a mixed-sex cohort of adult Sprague Dawley rats during early epileptogenesis. There were no sex differences in response to KA-induced SE, and neither did the stage of estrus influence SE severity. KA-induced SE caused significant astrogliosis and microgliosis across the hippocampus, piriform cortex, and amygdala. SAR treatment resulted in a significant reduction of microgliosis across brain regions. Microglial morphometrics such as branch length and the endpoints strongly correlated with CD68 expression in the vehicle-treated group but not in the SAR-treated group, indicating mitigation by SAR. KA-induced SE caused significant neuronal loss, including parvalbumin-positive inhibitory neurons, in both vehicle (VEH) and SAR-treated groups. SAR treatment significantly mitigated FJB-positive neuronal counts as compared to the VEH group. There was an increase in C3-positive reactive astrocytes in the VEH-treated group, and SAR treatment significantly reduced the increase in the piriform cortex. C3-positive astrogliosis significantly correlated with CD68 expression in the amygdala (AMY) of VEH-treated rats, and SAR treatment mitigated this relationship. There was a significant increase of pSrc(Y419)-positive microglia in both KA-treated groups with a statistically insignificant reduction by SAR. KA-induced SE caused the development of classical glial scars in the piriform cortex (PIR) in both KA-treated groups, while SAR treatment led to a 42.17% reduction in the size of glial scars. We did not observe sex differences in any of the parameters in this study. SAR, at the dose tested in the rat kainate model for a week in this study mitigated some of the markers of epileptogenesis in both sexes.
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Affiliation(s)
| | | | | | | | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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Vasanthi SS, Massey N, Nair SN, Mochel JP, Showman L, Thippeswamy T. Exploring the benefits of in-diet versus repeated oral dosing of saracatinib (AZD0530) in chronic studies: insights into pharmacokinetics and animal welfare. Front Vet Sci 2023; 10:1297221. [PMID: 38026620 PMCID: PMC10666625 DOI: 10.3389/fvets.2023.1297221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023] Open
Abstract
Saracatinib/AZD0530 (SAR), a Src tyrosine kinase inhibitor, mitigates seizure-induced brain pathology in epilepsy models upon repeated oral dosing. However, repeated dosing is stressful and can be challenging in some seizing animals. To overcome this issue, we have incorporated SAR-in-Diet and compared serum pharmacokinetics (PK) and brain concentrations with conventional repeated oral dosing. Saracatinib in solution or in-diet was stable at room temperature for >4 weeks (97 ± 1.56%). Adult Sprague Dawley rats on SAR-in-Diet consumed ~1.7 g/day less compared to regular diet (16.82 ± 0.6 vs. 18.50 ± 0.5 g/day), but the weight gain/day was unaffected (2.63 ± 0.5 g/day vs. 2.83 ± 0.2 g/day). Importantly, we achieved the anticipated SAR dose range from 2.5-18.7 mg/kg of rat in response to varying concentrations of SAR-in-Diet from 54 to 260 ppm of feed, respectively. There was a strong and significant correlation between SAR-in-Diet dose (mg/kg) and serum saracatinib concentrations (ng/ml). Serum concentrations also did not vary significantly between SAR-in-Diet and repeated oral dosing. The hippocampal saracatinib concentrations derived from SAR-in-Diet treatment were higher than those derived after repeated oral dosing (day 3, 546.8 ± 219.7 ng/g vs. 238.6 ± 143 ng/g; day 7, 300.7 ± 43.4 ng/g vs. 271.1 ± 62.33 ng/g). Saracatinib stability at room temperature and high serum and hippocampal concentrations in animals fed on SAR-in-Diet are useful to titer the saracatinib dose for future animal disease models. Overall, test drugs in the diet is an experimental approach that addresses issues related to handling stress-induced variables in animal experiments.
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Affiliation(s)
- Suraj S. Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Nyzil Massey
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Suresh N. Nair
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Kerala Veterinary and Animal Sciences University, Thrissur, India
| | - Jonathan P. Mochel
- Precision One Health, Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Lucas Showman
- W.M. Keck Metabolomics Research Laboratory, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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7
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Vasanthi SS, Rao NS, Samidurai M, Massey N, Meyer C, Gage M, Kharate M, Almanza A, Wachter L, Mafuta C, Trevino L, Carlo AM, Bryant E, Corson BE, Wohlgemuth M, Ostrander M, Showman L, Wang C, Thippeswamy T. Disease-modifying effects of a glial-targeted inducible nitric oxide synthase inhibitor (1400W) in mixed-sex cohorts of a rat soman (GD) model of epilepsy. J Neuroinflammation 2023; 20:163. [PMID: 37438764 PMCID: PMC10337207 DOI: 10.1186/s12974-023-02847-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 07/05/2023] [Indexed: 07/14/2023] Open
Abstract
BACKGROUND Acute exposure to seizurogenic organophosphate (OP) nerve agents (OPNA) such as diisopropylfluorophosphate (DFP) or soman (GD), at high concentrations, induce immediate status epilepticus (SE), reactive gliosis, neurodegeneration, and epileptogenesis as a consequence. Medical countermeasures (MCMs-atropine, oximes, benzodiazepines), if administered in < 20 min of OPNA exposure, can control acute symptoms and mortality. However, MCMs alone are inadequate to prevent OPNA-induced brain injury and behavioral dysfunction in survivors. We have previously shown that OPNA exposure-induced SE increases the production of inducible nitric oxide synthase (iNOS) in glial cells in both short- and long- terms. Treating with a water soluble and highly selective iNOS inhibitor, 1400W, for 3 days significantly reduced OPNA-induced brain changes in those animals that had mild-moderate SE in the rat DFP model. However, such mitigating effects and the mechanisms of 1400W are unknown in a highly volatile nerve agent GD exposure. METHODS Mixed-sex cohort of adult Sprague Dawley rats were exposed to GD (132 μg/kg, s.c.) and immediately treated with atropine (2 mg/kg, i.m) and HI-6 (125 mg/kg, i.m.). Severity of seizures were quantified for an hour and treated with midazolam (3 mg/kg, i.m.). An hour post-midazolam, 1400W (20 mg/kg, i.m.) or vehicle was administered daily for 2 weeks. After behavioral testing and EEG acquisition, animals were euthanized at 3.5 months post-GD. Brains were processed for neuroinflammatory and neurodegeneration markers. Serum and CSF were used for nitrooxidative and proinflammatory cytokines assays. RESULTS We demonstrate a significant long-term (3.5 months post-soman) disease-modifying effect of 1400W in animals that had severe SE for > 20 min of continuous convulsive seizures. 1400W significantly reduced GD-induced motor and cognitive dysfunction; nitrooxidative stress (nitrite, ROS; increased GSH: GSSG); proinflammatory cytokines in the serum and some in the cerebrospinal fluid (CSF); epileptiform spikes and spontaneously recurring seizures (SRS) in males; reactive gliosis (GFAP + C3 and IBA1 + CD68-positive glia) as a measure of neuroinflammation, and neurodegeneration (especially parvalbumin-positive neurons) in some brain regions. CONCLUSION These findings demonstrate the long-term disease-modifying effects of a glial-targeted iNOS inhibitor, 1400W, in a rat GD model by modulating reactive gliosis, neurodegeneration (parvalbumin-positive neurons), and neuronal hyperexcitability.
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Affiliation(s)
- Suraj S. Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Nikhil S. Rao
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Manikandan Samidurai
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Nyzil Massey
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Christina Meyer
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Meghan Gage
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Mihir Kharate
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Aida Almanza
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Logan Wachter
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Candide Mafuta
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Lily Trevino
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Adriana M. Carlo
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Elijah Bryant
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Brooke E. Corson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Morgan Wohlgemuth
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Morgan Ostrander
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Lucas Showman
- W.M. Keck Metabolomics Research Laboratory, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Chong Wang
- Department of Veterinary Diagnostic and Production Animal Medicine and Statistics, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, 50011 USA
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Gage M, Vasanthi SS, Meyer CM, Rao NS, Thedens DR, Kannurpatti SS, Thippeswamy T. Sex-based structural and functional MRI outcomes in the rat brain after soman (GD) exposure-induced status epilepticus. Epilepsia Open 2023; 8:399-410. [PMID: 36718979 PMCID: PMC10235578 DOI: 10.1002/epi4.12701] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/25/2023] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE Exposure to the nerve agent, soman (GD), induces status epilepticus (SE), epileptogenesis, and even death. Although rodent models studying the pathophysiological mechanisms show females to be more reactive to soman, no tangible sex differences in brains postexposure have been reported. In this study, we used multimodal imaging using MRI in adult rats to determine potential sex-based biomarkers of soman effects. METHODS Male and female Sprague Dawley rats were challenged with 1.2 × LD50 soman followed by medical countermeasures. Ten weeks later, the brains were analyzed via structural and functional MRI. RESULTS Despite no significant sex differences in the initial SE severity after soman exposure, long-term MRI-based structural and functional differences were evident in the brains of both sexes. While T2 MRI showed lesser soman-induced neurodegeneration, large areas of T1 enhancements occurred in females than in males, indicating a distinct pathophysiology unrelated to neurodegeneration. fMRI-based resting-state functional connectivity (RSFC), indicated greater reductions in soman-exposed females than in males, associating with the T1 enhancements (unrelated to neurodegeneration) rather than T2-hyperintensity or T1-hypointensity (representing neurodegeneration). The wider T1 enhancements associating with the decreased spontaneous neuronal activity in multiple resting-state networks in soman-exposed females than males suggest that neural changes unrelated to cellular atrophy impinge on brain function postexposure. Taken together with lower spontaneous neural activity in soman-exposed females, the results indicate some form of neuroprotective state that was not present in males. SIGNIFICANCE The results indicate that endpoints other than neurodegeneration may need to be considered to translate sex-based nerve agent effects in humans.
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Affiliation(s)
- Meghan Gage
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Suraj S Vasanthi
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Christina M Meyer
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Nikhil S Rao
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Daniel R Thedens
- Department of RadiologyCarver College of Medicine, The University of IowaIowa CityIowaUSA
| | - Sridhar S. Kannurpatti
- Department of Radiology, Rutgers Biomedical and Health SciencesNew Jersey Medical SchoolNewarkNew JerseyUSA
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Vasanthi SS, Rao NS, Samidurai M, Massey N, Meyer C, Gage M, Kharate M, Almanza A, Wachter L, Mafuta C, Trevino L, Carlo AM, Bryant E, Corson BE, Wohlgemuth M, Ostrander M, Wang C, Thippeswamy T. Disease-Modifying Effects of a Glial-targeted Inducible Nitric Oxide Synthase Inhibitor (1400W) in Mixed-sex Cohorts of a Rat Soman (GD) Model of Epilepsy. RESEARCH SQUARE 2023:rs.3.rs-2883247. [PMID: 37214912 PMCID: PMC10197763 DOI: 10.21203/rs.3.rs-2883247/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Background Acute exposure to seizurogenic organophosphate (OP) nerve agents (OPNA) such as diisopropylfluorophosphate (DFP) or soman (GD), at high concentrations, induce immediate status epilepticus (SE), reactive gliosis, neurodegeneration, and epileptogenesis as a consequence. Medical countermeasures (MCMs- atropine, oximes, benzodiazepines), if administered in < 20 minutes of OPNA exposure, can control acute symptoms and mortality. However, MCMs alone are inadequate to prevent OPNA-induced brain injury and behavioral dysfunction in survivors. We have previously shown that OPNA exposure-induced SE increases the production of inducible nitric oxide synthase (iNOS) in glial cells in both short- and long- terms. Treating with a water soluble and highly selective iNOS inhibitor, 1400W, for three days significantly reduced OPNA-induced brain changes in those animals that had mild-moderate SE in the rat DFP model. However, such mitigating effects and the mechanisms of 1400W are unknown in a highly volatile nerve agent GD exposure. Methods Mixed-sex cohort of adult Sprague Dawley rats were exposed to GD (132µg/kg, s.c.) and immediately treated with atropine (2mg/kg, i.m) and HI-6 (125mg/kg, i.m.). Severity of seizures were quantified for an hour and treated with midazolam (3mg/kg, i.m.). An hour post-midazolam, 1400W (20mg/kg, i.m.) or vehicle was administered daily for two weeks. After behavioral testing and EEG acquisition, animals were euthanized at 3.5 months post-GD. Brains were processed for neuroinflammatory and neurodegeneration markers. Serum and CSF were used for nitrooxidative and proinflammatory cytokines assays. Results We demonstrate a significant long-term (3.5 months post-soman) disease-modifying effect of 1400W in animals that had severe SE for > 20min of continuous convulsive seizures. 1400W significantly reduced GD-induced motor and cognitive dysfunction; nitrooxidative stress (nitrite, ROS; increased GSH: GSSG); proinflammatory cytokines in the serum and some in the cerebrospinal fluid (CSF); epileptiform spikes and spontaneously recurring seizures (SRS) in males; reactive gliosis (GFAP + C3 and IBA1 + CD68 positive glia) as a measure of neuroinflammation, and neurodegeneration (including parvalbumin positive neurons) in some brain regions. Conclusion These findings demonstrate the long-term disease-modifying effects of a glial-targeted iNOS inhibitor, 1400W, in a rat GD model by modulating reactive gliosis, neurodegeneration, and neuronal hyperexcitability.
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Rao NS, Meyer C, Vasanthi SS, Massey N, Samidurai M, Gage M, Putra M, Almanza AN, Wachter L, Thippeswamy T. DFP-Induced Status Epilepticus Severity in Mixed-Sex Cohorts of Adult Rats Housed in the Same Room: Behavioral and EEG Comparisons. Front Cell Dev Biol 2022; 10:895092. [PMID: 35620057 PMCID: PMC9127803 DOI: 10.3389/fcell.2022.895092] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/19/2022] [Indexed: 11/26/2022] Open
Abstract
Sex is a biological variable in experimental models. In our previous diisopropylfluorophosphate (DFP) studies, female rats required a higher dose of DFP to achieve a somewhat similar severity of status epilepticus (SE) as males. In those studies, male and female rats were bought separately from the same vendor, housed in different rooms, and the DFP used was from different batches. We had also shown that surgery for epidural electrodes implantation reduces the threshold for SE. Our recent study in the soman (GD) model using a mixed-sex cohort of rats housed individually but in the same room showed that females achieved significantly higher SE severity than males for the same dose of GD. In this study, we demonstrate that housing the mixed-sex cohorts in the same room and treating them with DFP (4 mg/kg, s.c.) from the same pool, though from different batches, yielded reproducible SE severity in both sexes and both telemetry (surgery) and non-telemetry (non-surgery) groups. We conducted experiments in four mixed-sex cohorts of adult Sprague-Dawley rats. In females, the surgery for implanting the telemetry devices reduced the latency to convulsive seizure (CS) and increased SE severity compared to non-telemetry females. However, there were no sex differences in latency or SE severity within telemetry or non-telemetry groups. Once animals reached CS stage ≥3, they remained in CS stage in both sexes until midazolam was administered. Midazolam (3 mg/kg, i.m.) treatment 1-one-hour post-DFP significantly reduced epileptiform spikes in both sexes. The mortality was only 2% in 24 h. Irrespective of sex or stage of estrous cycle or surgery, the animals had continuous convulsive SE for ∼40 min. In telemetry rats, electrographic changes correlated with behavioral seizures. However, there was a significant difference in SE severity and the latency between directly-observed behavioral CS and EEG-based CS quantification in both sexes. Overall, these results suggest that housing both sexes in the same room and treating with DFP in a mixed-sex cohort from the same pool of reagents will minimize variability in SE severity. Such rigorous experiments will yield better outcomes while testing disease-modifying agents in epilepsy models.
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Affiliation(s)
- Nikhil S Rao
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Christina Meyer
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Suraj S Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Nyzil Massey
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Manikandan Samidurai
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Meghan Gage
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Marson Putra
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Aida N Almanza
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Logan Wachter
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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