Assessment of the estrous cycle in rats after experimental blast-induced brain injury

Authors

DOI:

https://doi.org/10.26641/1997-9665.2025.4.36-41

Keywords:

blast-induced brain injury, estrous cycle, vaginal cytology, white rats, experiment.

Abstract

Background. An analysis of scientific sources studying the relationship between brain injury in women, particularly mild injury, and potential consequences for reproductive function, showed that there are currently certain gaps in knowledge regarding the potential mechanisms of menstrual cycle disorders and adverse pregnancy outcomes in women after concussion, which occurred as a result of both contact trauma and exposure to an explosive shock wave. Objective: to evaluate the duration and structure of the estrous cycle in female white rats after exposure to an air shock wave. Methods. Forty white sexually mature female rats were used to achieve the research objective. To study the duration and structure of the estrous cycle in females, vaginal smears were taken every day between 9 and 11 a.m. for 14 days. All rats selected to participate in the experiment were divided into four groups: intact (n=10), control (n=10), experimental group (n=10) exposed to a shock wave during the estrus phase, and experimental group (n=10) exposed to a shock wave during the diestrus phase. The air shock wave was reproduced in a device designed to study the effects of shock waves from explosions on the body. To obtain vaginal smears, we used the vaginal lavage technique. Statistical and mathematical analysis of the quantitative indicators of the estrous cycle was performed using the STATISTICA 6.1 computer program for statistical data processing. Results. Qualitative cytological analysis of vaginal smears in the experimental group of rats showed that their cellular composition was represented by either isolated or moderate numbers of neutrophils, a large number of small nuclear cells, the absence of large nucleated cells, non-nucleated keratinized cells, and moderate or significant relative cell density. According to the cytological analysis of vaginal smears in female rats exposed to an air shock wave, changes were found in the post-traumatic period in both the duration of the estrous cycle and the duration of individual stages of the estrous cycle. Conclusion. Experimental explosion-induced brain injury in sexually mature female rats led to a prolongation of the estrous cycle due to prolongation of the proestrus stage, regardless of the stage of the estrous cycle the female rat was in at the time of the traumatic impact. The cellular composition of vaginal smears in rats in the experimental group showed a decrease in the number of large nuclear cells and non-nuclear keratinized epithelial cells. The changes found can be considered an early marker of reproductive dysfunction after shock wave exposure.

References

  1. Ye Z, Li Z, Zhong S, Xing Q, Li K, Sheng W, Shi X, Bao Y. The recent two decades of traumatic brain injury: a bibliometric analysis and systematic review. Int J Surg. 2024;110(6):3745-59. doi: 10.1097/JS9.0000000000001367.
  2. Mortimer DS. Military Traumatic Brain Injury. Phys Med Rehabil Clin N Am. 2024;35(3):559-71. doi: 10.1016/j.pmr.2024.02.008.
  3. Brazinova A, Rehorcikova V, Taylor MS, Buckova V, Majdan M, Psota M, Peeters W, Feigin V, Theadom A, Holkovic L, Synnot A. Epidemiology of Traumatic Brain Injury in Europe: A Living Systematic Review. J Neurotrauma. 2021;38(10):1411-40. doi: 10.1089/neu.2015.4126.
  4. Haarbauer-Krupa J, Pugh MJ, Prager EM, Harmon N, Wolfe J, Yaffe K. Epidemiology of Chronic Effects of Traumatic Brain Injury. J Neurotrauma. 2021;38(23):3235-47. doi: 10.1089/neu.2021.0062.
  5. Haynes N, Goodwin T. Literature Review of Sex Differences in mTBI. Mil Med. 2023;188(5-6):e978-e984. doi: 10.1093/milmed/usab472.
  6. Snook ML, Henry LC, Sanfilippo JS, Zeleznik AJ, Kontos AP. Association of Concussion With Abnormal Menstrual Patterns in Adolescent and Young Women. JAMA Pediatr. 2017;171(9):879-86. doi: 10.1001/jamapediatrics.2017.1140.
  7. Adams RS, Akobirshoev I, Brenner LA, Katon JG, Mitra M. Pregnancy, Fetal, and Neonatal Outcomes Among Women With Traumatic Brain Injury. J Head Trauma Rehabil. 2023;38(3):E167-E176. doi: 10.1097/HTR.0000000000000807.
  8. Wunderle K, Hoeger KM, Wasserman E, Bazarian JJ. Menstrual phase as predictor of outcome after mild traumatic brain injury in women. J Head Trauma Rehabil. 2014;29(5):E1-8. doi: 10.1097/ HTR.0000000000000006.
  9. Roby PR, Grimberg A, Master CL, Arbogast KB. Menstrual Cycle Patterns After Concussion in Adolescent Patients. J Pediatr. 2023;262:113349. doi: 10.1016/j.jpeds.2023.02.002.
  10. Anto-Ocrah M, Cafferky V, Lewis V. Pregnancy After Concussion: A Clarion Call for Attention? J Head Trauma Rehabil. 2022;37(4):E268-E279. doi: 10.1097/HTR.0000000000000723.
  11. Goldman JM, Murr AS, Cooper RL. The rodent estrous cycle: characterization of vaginal cytology and its utility in toxicological studies. Birth Defects Res B Dev Reprod Toxicol. 2007;80(2):84-97. doi: 10.1002/bdrb.20106.
  12. Kozlova YV, Abdul-Ogli LV, Kosharnyi AV, Kytova IV, Korzachenko MA, inventors; Kozlova YV, assignee. Device for studying the effect of an explosion shock wave on the organism. Ukrainian patent UA 146858. 2021 Mar 24.
  13. Cora MC, Kooistra L, Travlos G. Vaginal Cytology of the Laboratory Rat and Mouse: Review and Criteria for the Staging of the Estrous Cycle Using Stained Vaginal Smears. Toxicologic Pathology. 2015;43(6):776-93. doi: 10.1177/ 0192623315570339.
  14. European Convention for the protection of vertebrate animals used for experimental and other scientific purposes. Strasburg: Council of Europe. 1986;123:52. Available from: https:// rm.coe.int/168007a67b.
  15. Zakon Ukrainy. Pro zakhyst tvaryn vid zhorstokogo povodzhennia [Law of Ukraine. On the protection of animals from cruelty]. Vidomosti Verkhovnoi Rady Ukrainy (VVR). 2006;27:230. Available from: http://zakon1.rada.gov.ua/laws/ show/3447-15
  16. Hubscher CH, Brooks DL, Johnson JR. A quantitative method for assessing stages of the rat estrous cycle. Biotech Histochem. 2005;80(2):79-87. doi: 10.1080/10520290500138422.
  17. Kozlov S, Kozlova Y, Bondarenko N, Bondarenko O. Histopathological and ultrastructural changes in the rats brain after air shock wave impact. Med. perspekt. [Internet]. 2024;29(1):16-22. Available from: https://journals.uran.ua/index.php/2307-0404/article/view/300497.

Downloads

Published

2025-12-03

How to Cite

Dvoretsky , D., & Kozlov , S. (2025). Assessment of the estrous cycle in rats after experimental blast-induced brain injury. Морфологія / Morphologia / Morfologìâ, 19(4), 36–41. https://doi.org/10.26641/1997-9665.2025.4.36-41

Issue

Vol. 19 No. 4 (2025)

Section

Статті

License

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

 The authors reserve the right to authorship of their work and transfer to the Journal the right to the first publication of this work under the terms of a license Creative commons Attribution 4.0 International (CC BY 4.0), which allows other people to freely distribute the published work with a mandatory reference to the authors of the original work and the first publication of the work in this journal.
        By submitting a manuscript to the editorial office of the Journal ‘Morphologia’ authors agree to transfer the rights to protect and use the manuscript (all supplemental materials, particularly protected objects such as photos, drawings, diagrams, tables, etc.), including the reproduction in the press and distribution via the Internet; translation of the manuscript into any language; export and import of journal copies with the Authors’ article in order to make it available for public. Authors convey the rights mentioned above to the editorial office without any temporal or territorial limitation all over the world. 
        The Authors guarantee that they have the exclusive rights to use the material transferred to editorial office. Editors are not responsible to third parties for contraventions of warranty given by the Authors. The considered rights are transferred to the editorial office since the moment when the current issue is signed for publishing. Reproduction of materials published in the Journal by other individuals and legal entities is possible only with the consent of Editorial office, with the obligatory indication of the full bibliographic reference of the primary publication. The Authors reserve the right to use the published material, its fragments and parts for teaching materials, oral presentations, dissertation thesis prepararion with obligatory bibliographic citation of the original paper. Electron copy of the published article, downloaded from official journal web-site in .pdf format may be put by authors on the official web-site of their institutions, any other official resources with open access.