Effects of methotrexate on RNA and purine synthesis of astrocytes in primary culture

Jocelyn H. Bruce-Gregorios, Ram P. Agarwal, Alan Oracion, Arnold Ramirez, Lin Lin

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

There is increasing evidence to indicate that astrocytes are primary targets for methotrexate (MTX) neurotoxicity. However, the mechanism by which MTX exerts its deleterious effect on astroglial cells is not known. Methotrexate acts by inhibiting dihydrofolate reductase and in other cell systems has been reported to inhibit thymidylate synthesis, purine synthesis or both. To determine the mechanism involved in MTX-induced toxicity to the nervous system, RNA synthesis was studied in two week-old primary astrocyte cultures by measuring [3H]Uridine (Urd) incorporation 24 hours after exposure to varying concentrations of MTX. De novo purine synthesis was also studied by measuring incorporation of [14C]glycine and [14C]formate in cultured astrocytes. The radioactivity level of incorporated Urd in culture decreased to 48%, 53% and 43% after exposure to 1, 10 and 100 μM MTX. Total [14C]glycine incorporation was not affected while incorporation of [14C]formate was almost completely inhibited by MTX. The MTX-induced inhibition of [3H]Urd incorporation was not reversed by concomitant addition of exogenous purine bases (1 and 10 μM adenine, guanine and hypoxanthine) or nucleosides (1 and 10 μM adenosine, guanosine and inosine) to the MTX-treated cultures. On the other hand, addition of formyl-tetrahydrofolate reversed the MTX-induced reduction in [3H]Urd incorporation, indicating that the RNA inhibition was due to depletion of folate-dependent substrates for purine synthesis. Our results provide evidence that inhibition of purine and RNA synthesis may be the underlying mechanism involved in MTX-induced injury to the astrocytes, and may be important in the pathogenesis of MTX encephalopathy.

Original languageEnglish
Pages (from-to)770-778
Number of pages9
JournalJournal of Neuropathology and Experimental Neurology
Volume50
Issue number6
StatePublished - Nov 1 1991
Externally publishedYes

Fingerprint

Methotrexate
Astrocytes
RNA
formic acid
Uridine
Glycine
purine
Inosine
Tetrahydrofolate Dehydrogenase
Hypoxanthine
Guanosine
Guanine
Brain Diseases
Adenine
Nucleosides
Folic Acid
Adenosine
Radioactivity
Nervous System

Keywords

  • Astrocyte
  • Methotrexate
  • Purine synthesis
  • RNA

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Neuroscience(all)

Cite this

Bruce-Gregorios, J. H., Agarwal, R. P., Oracion, A., Ramirez, A., & Lin, L. (1991). Effects of methotrexate on RNA and purine synthesis of astrocytes in primary culture. Journal of Neuropathology and Experimental Neurology, 50(6), 770-778.

Effects of methotrexate on RNA and purine synthesis of astrocytes in primary culture. / Bruce-Gregorios, Jocelyn H.; Agarwal, Ram P.; Oracion, Alan; Ramirez, Arnold; Lin, Lin.

In: Journal of Neuropathology and Experimental Neurology, Vol. 50, No. 6, 01.11.1991, p. 770-778.

Research output: Contribution to journalArticle

Bruce-Gregorios, JH, Agarwal, RP, Oracion, A, Ramirez, A & Lin, L 1991, 'Effects of methotrexate on RNA and purine synthesis of astrocytes in primary culture', Journal of Neuropathology and Experimental Neurology, vol. 50, no. 6, pp. 770-778.
Bruce-Gregorios, Jocelyn H. ; Agarwal, Ram P. ; Oracion, Alan ; Ramirez, Arnold ; Lin, Lin. / Effects of methotrexate on RNA and purine synthesis of astrocytes in primary culture. In: Journal of Neuropathology and Experimental Neurology. 1991 ; Vol. 50, No. 6. pp. 770-778.
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