A CHRONIC SCOPOLAMINE-INDUCED ANIMAL MODEL FOR COGNITIVE ALTERATIONS RESEARCH – ANATOMY AND METABOLISM
Abstract
As long as complete etiology and curative treatment of Alzheimer’s disease (AD) are not available, numerous animal species have been tested, but the ideal AD model has not been yet found. Although wild-type rodents do not develop β amyloidplaques or neurofibrillary tangles, rat species present some advantages for anatomical and functional AD modeling. Material and methods: Memory impairment was induced by intraperitoneal injection of 2 mg/kg scopolamine (Sco) into Wistar male rats. A control group received a similar injection with 0.2 mL physiological saline. Hybrid imaging acquisitions 18F-fluorodeoxyglucose PET/MRI (18F-FDG PET/MRI) were achieved after 14 days of administration and euthanasia for harvesting rat brains and cerebral samples preservation was accomplished after 28 consecutive days of treatment. Specific cerebral regions were visually evaluated and quantified using standardized uptake values, then were correlated with the anatomic regions harvested, comprising: the cerebral cortex, hippocampus, thalamus, and cerebellum, a separate sample being collected for each side. Results: In coronal view, 56 cerebral samples, 160 cerebral MRI, and over 800 18F-FDG PET cerebral images were obtained. Although anatomical macroscopic differences were not found between rats cerebral brains, in vivo functional imaging provided an obvious distinction between the saline-treated and the Sco-induced animals, changes that persist in long-term administration. Conclusions: The present study proves that the cerebral metabolism increase is maintained during chronic administration of Sco, with intense metabolism in the amygdala, the entorhinal cortex, and other specific cerebral regions specialized in memory processing. We emphasize the functional impact of Sco-induction correlated with anatomical implications after tissue dissection.
References
2. Ionita R, Postu PA, Mihasan M, et al. Ameliorative effects of Matricaria chamomilla L. hydroalcoholic extract on scopolamine-induced memory impairment in rats: A behavioral and molecular study. Phytomedicine 2018; 47: 113-20.
3. Batir-Marin D, Boev M, Cioanca O, et al. Neuroprotective and Antioxidant Enhancing Properties of Selective Equisetum Extracts. Molecules 2021; 26(9): 2565.
4. Singh O, Khanam Z, Misra N, Srivastava MK. Chamomile (Matricaria chamomilla L.): An overview. Pharmacogn Rev 2011; 5(9): 82-95.
5. Keefe JR, Mao JJ, Soeller I, Li QS, Amsterdam JD. Short-term open-label Chamomile (Matricaria chamomilla L.) therapy of moderate to severe generalized anxiety disorder. Phytomedicine 2016; 23: 1699-1705.
6. Dubois B, Villain N, Frisoni GB, et al. Clinical diagnosis of Alzheimer’s disease: recommendations of the International Working Group. Lancet Neurol. 2021; 20(6): 484-496.
7. Fernandez-Blazquez MA, Avila-Villanueva M, Maestu F, Medina M. Specific Features of Subjective Cognitive Decline Predict Faster Conversion to Mild Cognitive Impairment. J Alzheimers Dis 2016; 52(1): 271-281.
8. Butterfield DA, Halliwell B. Oxidative stress, dysfunctional glucose metabolism and Alzheimer disease. Nat Rev Neurosci 2019; 20(3): 148-160.
9. Gordon BA, Blazey TM, Su Y, et al. Spatial patterns of neuroimaging biomarker change in individuals from families with autosomal dominant Alzheimer’s disease: a longitudinal study. Lancet Neurol 2018; 17(3): 241-250.
10. Asaad M, Lee JH. A guide to using functional magnetic resonance imaging to study Alzheimer’s disease in animal models. Dis Model Mech 2018; 11(5): dmm031724.
11. Ellenbroek B, Youn J. Rodent models in neuroscience research: is it a rat race? Dis Model Mech 2016; 9(10): 1079-1087.
12. Colleluori G, Galli C, Severi I, Perugini J, Giordano A. Early Life Stress, Brain Development, and Obesity Risk: Is Oxytocin the Missing Link? Cells 2022; 11(4): 623.
13. Katz HB, Davies CA. Effects of differential environments on the cerebral anatomy of rats as a function of previous and subsequent housing conditions. Exp Neurol 1984; 83(2): 274-287.
14. Mainta IC, Perani D, Delattre BM, Assal F, Haller S, Vargas MI, et al. FDG PET/MR Imaging in Major Neurocognitive Disorders. Curr Alzheimer Res 2017; 14(2): 186-197.
15. Jack CR Jr, Bennett DA, Blennow K, Carrillo MC, Dunn B, Haeberlein SB, et al. NIA-AA Research Framework: Toward a biological definition of Alzheimer’s disease. Alzheimer’s Dement 2018; 14(4): 535-562.
16. Jawaid T, Jahan S, Kamal M. A comparative study of neuroprotective effect of angiotensin converting enzyme inhibitors against scopolamine-induced memory impairments in rats. J Adv Pharm Technol Res 2015; 6(3): 130-135.
17. Lee JC, Park JH, Ahn JH, et al. Effects of chronic scopolamine treatment on cognitive impairment and neurofilament expression in the mouse hippocampus. Mol Med Rep2018; 17(1): 1625-1632.
18. Nagy K, Toth M, Major P, et al. Performance evaluation of the small-animal nanoscan PET/MRI system. J Nucl Med 2013; 54: 1825-1832.
19. Pierozan P, Jerneren F, Ransome Y, Karlsson O. The choice of euthanasia method affects metabolic serum biomarkers. Basic Clin Pharmacol Toxicol 2017; 121: 113-118.
20. Valentim AM, Guedes SR, Pereira AM, Antunes LM. Euthanasia using gaseous agents in laboratory rodents. Lab Anim2016; 50: 241-253.
21. Leavy S, Underwood W, Anthony R, et al. American Veterinary Medical Association. AVMA guidelines for the euthanasia of animals: 2020 edition. Cited on January 22nd, 2022, from: https://www.avma.org/sites/default/files/2020-01/2020-Euthanasia-Final-1-17-20.pdf
22. IACUC-UIOWA, last reviewed 1/08/2020. Institutional Animal Care and Use Committee of IOWA University Policies and Guidelines for Vertebrate Animal Research and Euthanasia. Cited on January 22nd, 2022, from: https://animal.research.uiowa.edu/iacuc-guidelines-euthanasia
23. Close B, Baumans V, Banister K. Euthanasia of experimental animals. European Commission, Directorate-General for Environment, Publications Office, 1997. Cited on January 22nd, 2022, from: https://op.europa.eu/en/publication-detail/-/publication/ b0ecd88f -8c31-4a5f-9ebd-2c8ad4da4c14
24. Parkinson CM, O’Brien A, Albers TM, Simon MA, Clifford CB, Pritchett-Corning KR. Diagnostic necropsy and selected tissue and sample collection in rats and mice. J Vis Exp 2011; (54): 2966.
25. Kobeissy FH, editor. Brain Neurotrauma: Molecular, Neuropsychological, and Rehabilitation Aspects. Boca Raton (FL): CRC Press/Taylor & Francis. 2015; Chapter 15.3.2. Brain Removal: 8-9.
26. Zhang W, Liu LF, Xiong YJ, et al. Effect of in vitro storage duration on measured mechanical properties of brain tissue. Sci Rep 2018; 8(1): 1247 / doi: 10.1038/s41598-018-19687-2.
27. Asai M, Fujikawa A, Noda A, Miyoshi S, Matsuoka N, Nishimura S. Donepezil - and scopolamine-induced rCMRglu changes assessed by PET in conscious rhesus monkeys. Ann Nucl Med 2009; 23(10): 877-882.
28. Abdelghany AK, El-Kashlan AM, Emeash HH, et al. Long-term scopolamine treatment altered locomotor, exploratory and anxiety-like behaviors of albino rats. Beni-Suef Univ J Basic Appl Sci 2022; 11: 7.
29. Anagnostaras SG, Gale GD, Fanselow MS. The hippocampus and Pavlovian fear conditioning: reply to Bast et al. Hippocampus 2002; 12(4): 561-565.
30. Treuting P, Dintzis S, Montine KS, editors. Comparative Anatomy and Histology. A Mouse, Rat, and Human Atlas. 2nd Edition. Elsevier Academic Press. 2017; Chapter 20. Nervous System: 403-44. eBook ISBN: 9780128029190. Hardcover ISBN: 9780128029008.
31. Shirakawa T, Mitsuoka K, Kuroda K, et al. [18F]FDG-PET as an imaging biomarker to NMDA receptor antagonist-induced neurotoxicity. Toxicol Sci 2013; 133(1): 13-21.
32. Somogyi G, Hlatky D, Spisák T, et al. Deciphering the scopolamine challenge rat model by preclinical functional MRI. Sci Rep 2021; 11: 10873.
33. Wong D, Makowska IJ, Weary DM. Rat aversion to isoflurane versus carbon dioxide. Biol Lett 2012; 9(1): 20121000.
34. Waerzeggers Y, Monfared P, Viel T, Winkeler A, Jacobs AH. Mouse models in neurological disorders: Applications of non-invasive imaging. Biochim Biophys Acta 2010; 1802(10): 819-839.

COPYRIGHT
Once an article is accepted for publication, MSJ requests a transfer of copyrights for published articles.
COPYRIGHT TRANSFER FORM FOR
REVISTA MEDICO-CHIRURGICALĂ A SOCIETĂȚII DE MEDICI ȘI NATURALIȘTI DIN IAȘI /
THE MEDICAL-SURGICAL JOURNAL OF THE SOCIETY OF PHYSICIANS AND NATURALISTS FROM IASI
We, the undersigned authors of the manuscript entitled
_____________________________________________________________________________________
_____________________________________________________________________________________
warrant that this manuscript, which is submitted for publication in the REVISTA MEDICO-CHIRURGICALĂ, has not been published and it is not under consideration for publication in another journal.
- we give the consent for publication in the REVISTA MEDICO-CHIRURGICALĂ, in printed and electronic format and we transfer unconditioned and complete the copyright of this manuscript to the REVISTA MEDICO-CHIRURGICALĂ, in the event of its acceptance.
- the manuscript does not break the intellectual property rights of any other person.
- we have read the submitted version of the manuscript and we are fully responsible for the content.
Names and signatures of authors / copyright owners (the following sequence is the authorship of the article):
- ______________________________/_________________________
- ______________________________/_________________________
- ______________________________/_________________________
N.B. All the authors must sign this form