Vol. 130 No. 1 (2026)
Original Article

Caffeine protects the blood brain barrier in type 2 diabetic rats, a histological and immunohistochemical study

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  • Manal A. Othman,
  • Nagi Bakhit,
  • Aisha Rashid,
  • Yasin Tayem
Manal A. Othman
Department of Anatomy, College of Medicine and Health Sciences, Arabian Gulf University, Manama, Bahrain
Nagi Bakhit
Department of Anatomy, College of Medicine and Health Sciences, Arabian Gulf University, Manama, Bahrain
Aisha Rashid
Department of Anatomy, College of Medicine and Health Sciences, Arabian Gulf University, Manama, Bahrain
Yasin Tayem
Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Arabian Gulf University, Manama, Bahrain
DOI: https://doi.org/10.36253/ijae-17382

Published 2026-09-05

Keywords

  • Blood brain barrier,
  • Caffeine,
  • Occludin,
  • Pericyte,
  • TGF-β1,
  • Type 2 diabetes
    • ...More
    Less

How to Cite

Othman, M. A., Bakhit, N., Rashid, A., & Tayem, Y. I. (2026). Caffeine protects the blood brain barrier in type 2 diabetic rats, a histological and immunohistochemical study. Italian Journal of Anatomy and Embryology, 130(1), 19–30. https://doi.org/10.36253/ijae-17382

Copyright (c) 2026 Manal A. Othman, Nagi Bakhit, Aisha Rashid, Yasin Tayem

Creative Commons License

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

Funding data

Abstract

Type 2 diabetes (T2D) is considered one of the metabolic conditions which may lead to degeneration of the central nervous system. The blood brain barrier (BBB) is recently recognized as a target that might be compromised in T2D. The pericyte and tight junction proteins, are major components of the BBB, that might be affected by diabetes. This may result in hyperpermeability of the BBB to toxic or hazardous substances, and this might affect its integrity. The current study addresses the effect of T2D on the BBB dysfunction and the role of caffeine to improve this condition. A rat model of T2D was used by feeding the rats with high calorie diet and injecting them with a single lower dose of streptozotocin. Diabetic rats were given caffeine orally for 5 weeks. At the end of the experiment (8 weeks), the rats were sacrificed, and their brains were processed for general histology and immunohistochemistry. The following markers were used: α-smooth muscle actin (α-SMA), occludin (tight junction protein) and transforming growth factor β1 (TGF-β1). There were degenerative changes in the cytoarchitecture of the CA1 area of the hippocampus. Immunohistochemistry revealed decrease in immunostaining of α-SMA and occludin and increase in TGF-β1 immunostaining, in diabetic rats. Caffeine intake resulted in improvement of the degenerative changes and reversal of the expression of the immunohistochemical markers. This study investigated the structural changes of the BBB in T2D, manifested by disruption of pericytes and tight junctions, with improvement of these findings after administration of caffeine. 

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References

  1. Aderinto N., Olatunji G., Abdulbasit M., Ashinze P., Faturoti O., Ajagbe A., Ukoaka B., Aboderin G. (2023) The impact of diabetes in cognitive impairment: A review of current evidence and prospects for future investigations. Medicine. Oct 27;102(43):e35557. https://doi.org/10.1097/MD.0000000000035557.
  2. Awashra A., AbuBaha M., Mahafdah B., Sarama A., Alattar D., AbuBaha B., Abu-Khazneh O., Emara A, Milhem A., Elgendy M.S., Shubietah A. (2026) Caffeine as a cardiovascular protective agent: a comprehensive review of mechanisms and outcomes. European journal of medical research. Mar 4. https://doi.org/10.1186/s40001-026-04089-2.
  3. Bancroft J.D., Gamble M., Suvarna S.K., Layton C. (2019) Theory and practice of histological techniques. 8th ed. Philadelphia: Elsevier.
  4. Basak M., Laskar M.A. (2024) Pathophysiology, lifestyle intervention and complications of Type-2 diabetes: A review. Journal of Applied Pharmaceutical Research. Jun 30;12(3):01-10. https://doi.org/10.69857/joapr.v12i3.482.
  5. Chaulagain B., Gothwal A., Lamptey R.N., Trivedi R., Mahanta A.K., Layek B., Singh J. (2023) Experimental models of in vitro blood–brain barrier for CNS drug delivery: an evolutionary perspective. International journal of molecular sciences. Jan 31;24(3):2710. https://doi.org/10.3390/ijms24032710.
  6. Chen T., Dai Y., Hu C., Lin Z., Wang S., Yang J., Zeng L., Li S., Li W. (2024) Cellular and molecular mechanisms of the blood-brain barrier dysfunction in neurodegenerative diseases. Fluids Barriers CNS. Jul 19;21(1):60. https://doi.org/10.1186/s12987-024-00557-1.
  7. Conti F., Lazzara F., Romano G.L., Platania C.B.M., Drago F., Bucolo C. (2022) Caffeine protects against retinal inflammation. Front Pharmacol. Jan 6;12:824885. https://doi.org/10.3389/fphar.2021.824885.
  8. da Silva Neves, L., de Mattos, G.V.R.M., Oliveira-Nazareth, Y., da Silva, R.S. and Campello-Costa, P. (2025) Effects of caffeine on neuroinflammation in anxiety and depression: a systematic review of rodent studies. Translational Psychiatry, 15(1), p.477. https://doi.org/10.1038/s41398-025-03668-x.
  9. El‐Ghazawi K., Eyo U.B., Peirce S.M. (2024) Brain microvascular pericyte pathology linking Alzheimer’s disease to diabetes. Microcirculation. Oct;31(7):e12877. https://doi.org/10.1111/micc.12877.
  10. Fan F., Geurts A.M., Murphy S.R., Pabbidi M.R., Jacob H.J., Roman R.J. (2015) Impaired myogenic response and autoregulation of cerebral blood flow is rescued in CYP4A1 transgenic Dahl salt-sensitive rat. Am J Physiol Regul Integr Comp Physiol 308: R379–R390. https://doi.org/10.1152/ajpregu.00256.2014.
  11. Garg P., Duggal N. (2022) Type 2 diabetes mellitus, its impact on quality of life and how the disease can be managed-a review, Obesity Medicine, Volume 35, 100459, https://doi.org/10.1016/j.obmed.2022.100459.
  12. Gopal S.S., Kaur M., Lanzkron S., Srivastava A.K. (2026) The breakdown of neurovascular barriers: molecular mechanisms of tight junction dysfunction. Molecular Neurobiology. Jan;63(1):273. https://doi.org/10.1007/s12035-025-05592-z.
  13. Han Y., Wu H., Sun S., Zhao R., Deng Y., Zeng S., Chen J. (2023) Effect of high fat diet on disease development of polycystic ovary syndrome and lifestyle intervention strategies. Nutrients. May 8;15(9):2230. https://doi.org/10.3390/nu15092230.
  14. Hong C.T., Chan L., Bai C.H. (2023) The Effect of Caffeine on the Risk and Progression of Parkinson’s Disease: A Meta-Analysis. Nutrients. 2020;12:1860. https://doi.org/10.3390/nu12061860. Erratum in Nutrients, 15, 699.
  15. Ikeda-Murakami K., Tani N., Ikeda T., Aoki Y., Ishikawa T. (2022) Central Nervous System Stimulants Limit Caffeine Transport at the Blood-Cerebrospinal Fluid Barrier. Int J Mol Sci. Feb 7;23(3):1862. https://doi.org/10.3390/ijms23031862.
  16. Kadry H., Noorani B., Cucullo L. (2020) A blood-brain barrier overview on structure, function, impairment, and biomarkers of integrity. Fluids Barriers CNS. Nov 18;17(1):69. https://doi.org/10.1186/s12987-020-00230-3.
  17. Kim S., Jung U.J., Kim S.R. (2025) The Crucial Role of the Blood-Brain Barrier in Neurodegenerative Diseases: Mechanisms of Disruption and Therapeutic Implications. J Clin Med. Jan 9;14(2):386. https://doi.org/10.3390/jcm14020386.
  18. Lenzi F.R., Filardi T. (2023) Social determinants of vulnerabilities in type 2 diabetes: a call to action. Journal of Endocrinological Investigation. Apr;46(4):841-4. https://doi.org/10.1007/s40618-022-01952-x.
  19. Li F., Liu X., Jiang B., Li X., Wang Y., Chen X., Su Y., Wang X., Luo J., Chen L., et al. (2024) Tea, coffee, and caffeine intake and risk of dementia and Alzheimer’s disease: A systematic review and meta-analysis of cohort studies. Food Funct. 15:8330–8344. https://doi.org/10.1039/D4FO01750A.
  20. Li X., Cai Y., Zhang Z., Zhou J. (2022) Glial and Vascular Cell Regulation of the Blood-Brain Barrier in Diabetes. Diabetes & Metabolism Journal. 46: 222-238. https://api.semanticscholar.org/CorpusID:247521156}
  21. Lin L., Wu Y., Chen Z., Huang L., Wang L., Liu L. (2021) Severe Hypoglycemia contributing to cognitive dysfunction in diabetic mice is associated with pericyte and blood-brain barrier dysfunction. Front Aging Neurosci. Nov 26;13:775244. https://doi.org/10.3389/fnagi.2021.775244.
  22. Liu Y., Zhang H., Wang S., Guo Y., Fang X., Zheng B., Gao W., Yu H., Chen Z., Roman R.J., Fan F. (2021) Reduced pericyte and tight junction coverage in old diabetic rats are associated with hyperglycemia-induced cerebrovascular pericyte dysfunction. Am J Physiol Heart Circ Physiol. Feb 1;320(2):H549-H562. https://doi.org/10.1152/ajpheart.00726.2020.
  23. Lopes C.R., Oliveira A., Gaspar I., Rodrigues M.S., Santos J., Szabó E., Silva H.B., Tomé Â.R., Canas P.M., Agostinho P., Carvalho R.A., Cunha R.A., Simões A.P., Lopes J.P., Ferreira S.G. (2023) Effects of Chronic Caffeine Consumption on Synaptic Function, Metabolism and Adenosine Modulation in Different Brain Areas. Biomolecules. Jan 4;13(1):106. https://doi.org/10.3390/biom13010106.
  24. Machida T., Dohgu S., Takata F., Matsumoto J., Kimura I., Koga M., Nakamoto K., Yamauchi A., Kataoka Y. (2017) Role of thrombin-PAR1-PKCθ/δ axis in brain pericytes in thrombin-induced MMP-9 production and blood-brain barrier dysfunction in vitro. Neuroscience. 2017 May 14;350:146-157. https://doi.org/10.1016/j.neuroscience.2017.03.026.
  25. Meijer W.C., Gorter J.A. (2024) Role of blood–brain barrier dysfunction in the development of poststroke epilepsy. Epilepsia. 65:2519–2536. https://doi.org/10.1111/epi.18072.
  26. Mezo-González C.E., Daher Abdi A., Reyes-Castro L.A., Olvera Hernández S., Almeida C., Croyal M., Aguesse A., Gavioli E.C., Zambrano E., Bolaños-Jiménez F. (2022) Learning deficits induced by high-calorie feeding in the rat are associated with impaired brain kynurenine pathway metabolism. International Journal of Tryptophan Research. Jul;15:11786469221111116. https://doi.org/10.1177/11786469221111116.
  27. Moran C., Beare R., Wang W., Callisaya M., Srikanth V. (2019) Alzheimer’s Disease Neuroimaging Initiative (ADNI), Alzheimer’s Disease Neuroimaging Initiative (ADNI). Type 2 diabetes mellitus, brain atrophy, and cognitive decline. Neurology. Feb 19;92(8):e823-30. https://doi.org/10.1212/WNL.0000000000006955.
  28. Onaolapo O.J., Onaolapo A.Y., Akanmu M.A., Olayiwola G. (2015) Caffeine/sleep-deprivation interaction in mice produces complex memory effects. Ann Neurosci 22(3):139–149. https://doi.org/10.5214/ans.0972.7531.220304.
  29. Othman M.A., Fadel R., Tayem Y., Jaradat A., Rashid A., Fatima A., Al-Mahameed A.E., Nasr El-Din W.A. (2023). Caffeine protects against hippocampal alterations in type 2 diabetic rats via modulation of gliosis, inflammation and apoptosis. Cell Tissue Res 392, 443–466 https://doi.org/10.1007/s00441-022-03735-5
  30. Ősz B.E., Jîtcă G., Ștefănescu R.E., Pușcaș A., Tero-Vescan A., Vari C.E. (2022) Caffeine and its antioxidant properties—it is all about dose and source. International journal of molecular sciences. Oct 28;23(21):13074. https://doi.org/10.3390/ijms232113074.
  31. Paxinos G., Watson C. (2013) The rat brain in stereotaxic coordinates, 7th edn. Academic Press, Amsterdam.
  32. Reyahi A., Nik A.M., Ghiami M., Gritli-Linde A., Pontén F., Johansson B.R., Carlsson P. (2015) Foxf2 Is Required for Brain Pericyte Differentiation and Development and Maintenance of the Blood-Brain Barrier. Dev Cell. Jul 6;34(1):19-32. https://doi.org/10.1016/j.devcel.2015.05.008.
  33. Rom S., Heldt N.A., Gajghate S., Seliga A., Reichenbach N.L., Persidsky Y. (2020) Author Correction: Hyperglycemia and advanced glycation end products disrupt BBB and promote occludin and claudin-5 protein secretion on extracellular microvesicles. Sci Rep. 2020 Oct 28;10(1):18828. https://doi.org/10.1038/s41598-020-75940-7. Erratum for: Sci Rep. 2020 Apr 29;10(1):7274. https://doi.org/10.1038/s41598-020-64349-x.
  34. Ruggiero M., Calvello R., Porro C., Messina G., Cianciulli A., Panaro M.A. (2022) Neurodegenerative diseases: Can caffeine be a powerful ally to weaken neuroinflammation?. International Journal of Molecular Sciences. Oct 26;23(21):12958. https://doi.org/10.3390/ijms232112958.
  35. Sharma B., Agriantonis G., Dawson-Moroz S., Brown R., Simon W., Ebelle D., Chapelet J., Cardona A., Soni A., Siddiqui M., Patel B., Cheerasarn S., Chang J., Cobb L., John F., Hasan M.M., Garcia C., Shaefee Z., Twelker K.D., Bhatia N., Whittington J. (2025) Caffeine: A Neuroprotectant and Neurotoxin in Traumatic Brain Injury (TBI). Nutrients. Jun 4;17(11):1925. https://doi.org/10.3390/nu17111925.
  36. Sharma V.K., Sharma A., Verma K.K., Gaur P.K., Kaushik R., Abdali B. (2023) A comprehensive review on pharmacological potentials of caffeine. Journal of Applied Pharmaceutical Sciences and Research. Dec 14;6(3):16-26. https://doi.org/10.31069/japsr.v6i3.04.
  37. Song X., Singh M., Lee K.E., Vinayagam R., Kang S.G. (2024) Caffeine: A multifunctional efficacious molecule with diverse health implications and emerging delivery systems. Int J Mol Sci. Nov 8;25(22):12003. https://doi.org/10.3390/ijms252212003.
  38. Stockwell J., Jakova E., Cayabyab F.S. (2017) Adenosine A1 and A2A Receptors in the Brain: Current Research and Their Role in Neurodegeneration. Molecules. 22:676. https://doi.org/10.3390/molecules22040676.
  39. Szablewski L. (2025) Associations Between Diabetes Mellitus and Neurodegenerative Diseases. International Journal of Molecular Sciences. 26(2):542. https://doi.org/10.3390/ijms26020542.
  40. Yu T., Wang Z., Chen Y., Xiang Y., Wu M., Zhang M., Yin X., Chen Z. (2025) Blood–brain barrier (BBB) dysfunction in CNS diseases: paying attention to pericytes. CNS Neuroscience & Therapeutics. May;31(5):e70422. https://doi.org/10.1111/cns.70422.
  41. Vargas-Pozada E.E., Ramos-Tovar E., Rodriguez-Callejas J.D., Cardoso-Lezama I., Galindo-Gómez S., Talamás-Lara D., Vásquez-Garzón V.R., Arellanes-Robledo J., Tsutsumi V., Villa-Treviño S., et al. (2022) Caffeine Inhibits NLRP3 Inflammasome Activation by Downregulating TLR4/MAPK/NF-ΚB Signaling Pathway in an Experimental NASH Model. Int. J. Mol. Sci. 23:9954. https://doi.org/10.3390/ijms23179954.
  42. Zhang L., Huang Y.J., Sun J.P., Zhang T.Y., Liu T.L., Ke B., Shi X.F., Li H., Zhang G.P., Ye Z.Y., Hu J. (2021) Protective effects of calorie restriction on insulin resistance and islet function in STZ-induced type 2 diabetes rats. Nutrition & metabolism. May 5;18(1):48. https://doi.org/10.1186/s12986-021-00575-y.
  43. Zhang S., Zhang Y., Wen Z., Yang Y., Bu T., Bu X., Ni Q. (2023) Cognitive dysfunction in diabetes: abnormal glucose metabolic regulation in the brain. Frontiers in endocrinology. Jun 16;14:1192602. https://doi.org/10.3389/fendo.2023.1192602.
  44. Zhou Y., Wei L., Gao S., Wang J., Hu Z. (2023) Characterization of diffusion magnetic resonance imaging revealing relationships between white matter disconnection and behavioral disturbances in mild cognitive impairment: a systematic review. Front. Neurosci. 17:1209378. https://doi.org/10.3389/fnins.2023.1209378.

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