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Awathale SN, Waghade AM, Kawade HM, Jadhav G, Choudhary AG, Sagarkar S, Sakharkar AJ, Subhedar NK, Kokare DM. Neuroplastic Changes in the Superior Colliculus and Hippocampus in Self-rewarding Paradigm: Importance of Visual Cues. Mol Neurobiol 2021; 59:890-915. [PMID: 34797522 DOI: 10.1007/s12035-021-02597-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/11/2021] [Indexed: 12/21/2022]
Abstract
Coincident excitation via different sensory modalities encoding objects of positive salience is known to facilitate learning and memory. With a view to dissect the contribution of visual cues in inducing adaptive neural changes, we monitored the lever press activity of a rat conditioned to self-administer sweet food pellets in the presence/absence of light cues. Application of light cues facilitated learning and consolidation of long-term memory. The superior colliculus (SC) of rats trained on light cue showed increased neuronal activity, dendritic branching, and brain-derived neurotrophic factor (BDNF) protein and mRNA expression. Concomitantly, the hippocampus showed augmented neurogenesis as well as BDNF protein and mRNA expression. While intra-SC administration of U0126 (inhibitor of ERK 1/2 and long-term memory) impaired memory formation, lidocaine (local anaesthetic) hindered memory recall. The light cue-dependent sweet food pellet self-administration was coupled with increased efflux of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens shell (AcbSh). In conditioned rats, pharmacological inhibition of glutamatergic signalling in dentate gyrus (DG) reduced lever press activity, as well as DA and DOPAC secretion in the AcbSh. We suggest that the neuroplastic changes in the SC and hippocampus might represent memory engrams sculpted by visual cues encoding reward information.
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Affiliation(s)
- Sanjay N Awathale
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, 440 033, India
| | - Akash M Waghade
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, 440 033, India
| | - Harish M Kawade
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, 440 033, India
| | - Gouri Jadhav
- Department of Biotechnology, Savitribai Phule Pune University, Pune, 411 007, India
| | - Amit G Choudhary
- Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pune, 411 008, India
| | - Sneha Sagarkar
- Department of Zoology, Savitribai Phule Pune University, Pune, 411 007, India
| | - Amul J Sakharkar
- Department of Biotechnology, Savitribai Phule Pune University, Pune, 411 007, India
| | - Nishikant K Subhedar
- Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pune, 411 008, India
| | - Dadasaheb M Kokare
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, 440 033, India.
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González EA, Calsbeek JJ, Tsai YH, Tang MY, Andrew P, Vu J, Berg EL, Saito NH, Harvey DJ, Supasai S, Gurkoff GG, Silverman JL, Lein PJ. Sex-specific acute and chronic neurotoxicity of acute diisopropylfluorophosphate (DFP)-intoxication in juvenile Sprague-Dawley rats. Curr Res Toxicol 2021; 2:341-356. [PMID: 34622217 PMCID: PMC8484742 DOI: 10.1016/j.crtox.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/12/2022] Open
Abstract
Preclinical efforts to improve medical countermeasures against organophosphate (OP) chemical threat agents have largely focused on adult male models. However, age and sex have been shown to influence the neurotoxicity of repeated low-level OP exposure. Therefore, to determine the influence of sex and age on outcomes associated with acute OP intoxication, postnatal day 28 Sprague-Dawley male and female rats were exposed to the OP diisopropylfluorophosphate (DFP; 3.4 mg/kg, s.c.) or an equal volume of vehicle (∼80 µL saline, s.c.) followed by atropine sulfate (0.1 mg/kg, i.m.) and pralidoxime (2-PAM; 25 mg/kg, i.m.). Seizure activity was assessed during the first 4 h post-exposure using behavioral criteria and electroencephalographic (EEG) recordings. At 1 d post-exposure, acetylcholinesterase (AChE) activity was measured in cortical tissue, and at 1, 7, and 28 d post-exposure, brains were collected for neuropathologic analyses. At 1 month post-DFP, animals were analyzed for motor ability, learning and memory, and hippocampal neurogenesis. Acute DFP intoxication triggered more severe seizure behavior in males than females, which was supported by EEG recordings. DFP caused significant neurodegeneration and persistent microglial activation in numerous brain regions of both sexes, but astrogliosis occurred earlier and was more severe in males compared to females. DFP males and females exhibited pronounced memory deficits relative to sex-matched controls. In contrast, acute DFP intoxication altered hippocampal neurogenesis in males, but not females. These findings demonstrate that acute DFP intoxication triggers seizures in juvenile rats of both sexes, but the seizure severity varies by sex. Some, but not all, chronic neurotoxic outcomes also varied by sex. The spatiotemporal patterns of neurological damage suggest that microglial activation may be a more important factor than astrogliosis or altered neurogenesis in the pathogenesis of cognitive deficits in juvenile rats acutely intoxicated with OPs.
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Key Words
- 2-PAM, pralidoxime
- AChE, acetylcholinesterase
- AS, atropine-sulfate
- BChE, butyrylcholinesterase
- CT, computed tomography
- ChE, cholinesterase
- Cognitive deficits
- DFP, diisopropylfluorophosphate
- EEG, electroencephalogram
- FJC, Fluoro-Jade C
- Neurodegeneration
- Neurogenesis
- Neuroinflammation
- OP, organophosphate
- PBS, phosphate-buffered saline
- ROI, region of interest
- SE, status epilepticus
- Seizures
- Sex differences
- T2w, T2-weighted
- VEH, vehicle
- i.m., intramuscular
- i.p., intraperitoneal
- s.c., subcutaneous
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Affiliation(s)
- Eduardo A. González
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Jonas J. Calsbeek
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Yi-Hua Tsai
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Mei-Yun Tang
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Peter Andrew
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Joan Vu
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Elizabeth L. Berg
- Department of Psychiatry, University of California, Davis, School of Medicine, 2230, Stockton Boulevard, Sacramento, CA 95817, USA
| | - Naomi H. Saito
- Department of Public Health Sciences, University of California, Davis, One Shields Avenue, School of Medicine, Davis, CA 95616, USA
| | - Danielle J. Harvey
- Department of Public Health Sciences, University of California, Davis, One Shields Avenue, School of Medicine, Davis, CA 95616, USA
| | - Suangsuda Supasai
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Gene G. Gurkoff
- Department of Neurological Surgery, University of California, Davis, School of Medicine, 4860 Y Street, Sacramento, CA 95817, USA
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Jill L. Silverman
- Department of Psychiatry, University of California, Davis, School of Medicine, 2230, Stockton Boulevard, Sacramento, CA 95817, USA
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA 95817, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA 95817, USA
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