Inhibition of hippocampal cell proliferation by methotrexate in rats is not potentiated by the presence of a tumor

Brain Res Bull. 2010 Mar 16;81(4-5):472-6. doi: 10.1016/j.brainresbull.2009.10.006. Epub 2009 Oct 12.


Methotrexate is a widely used cytostatic in chemotherapy cocktails for the treatment of cancer but is associated with cognitive impairment. Previous animal studies indicated that methorexate decreases hippocampal cell proliferation, which might contribute to the observed cognitive impairment. However, clinical studies have shown that cognitive impairment can also be noticed in some cancer patients before any systemic treatment is initiated. We aim in the present study to discern whether hippocampal cell proliferation is negatively affected by tumor growth and if the presence of a tumor amplifies the effects of methotrexate. Buffalo rats were subcutaneously injected with PBS or Morris Hepatoma 7777 cells to induce a tumor. Two weeks after this injection the animals received an intraperitoneal injection of methotrexate or saline. Three weeks later hippocampal cell proliferation was quantified using immunohistochemical staining. Treatment with Morris Hepatoma 7777 cells decreased the number of proliferating cells as compared to control animals. An overall tumor effect was absent mainly because methotrexate treatment significantly decreased cell proliferation with no differences between animals with or without a tumor. Neither methotrexate nor the tumor induced pica behavior. These findings indicate that although the presence of a tumor reduces hippocampal cell proliferation it does not affect the negative effect of methotrexate on this plasticity marker. Since sickness behavior is not induced by methotrexate or tumor presence it does not play a role in the development of cognitive deficits. This study further indicates that the effects of methotrexate on brain and behavior can be studied in healthy animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / pharmacology*
  • Body Weight / drug effects
  • Body Weight / physiology
  • Brain Neoplasms / drug therapy*
  • Brain Neoplasms / physiopathology
  • Carcinoma, Hepatocellular / drug therapy
  • Carcinoma, Hepatocellular / physiopathology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Feeding Behavior / drug effects
  • Feeding Behavior / physiology
  • Hippocampus / drug effects*
  • Hippocampus / physiopathology
  • Immunohistochemistry
  • Liver Neoplasms / drug therapy
  • Liver Neoplasms / physiopathology
  • Male
  • Methotrexate / pharmacology*
  • Neoplasm Transplantation
  • Pica / chemically induced
  • Pica / physiopathology
  • Rats
  • Rats, Inbred BUF


  • Antimetabolites, Antineoplastic
  • Methotrexate