Inhibiting glutamate: a treatment for brain tumours?
Inhibiting the secretion of glutamate, an amino acid
neurotransmitter, could provide a new approach to treating brain tumours,
American researchers say. Glioma tumour cells secrete glutamate which,
when present in excess, can cause acute degeneration of neurones.
Dr Takahiro Takano, New York Medical College, and
colleagues implanted glioma cells into adult rats and observed the effects
of glutamate receptor antagonists such as MK801 and memantine.
The researchers found that treatment with MK801
and memantine slowed the growth of glutamate-secreting tumours in situ.
They say that this indicates that glutamate-dependent neurotoxicity aids
tumour progression and that the inflammatory response accompanying neuronal
degeneration may be providing a favourable environment for tumour expansion
(Nature Medicine 2001;7:1010).
In an accompanying editorial, Dr Jeffrey Rothstein
and Dr Henry Brem, Johns Hopkins University, Baltimore, Maryland, say
that the researchers demonstrate that release of glutamate is directly
related to tumour growth — the more glutamate the tumours release, the
larger the tumour mass.
“The findings make it tempting to speculate that
glutamate carves an excitotic path of destruction through brain tissue,
thus explaining the particularly invasive and destructive nature of gliomas,”
they say. They add that the research opens up an entirely new treatment
approach to fatal central nervous system (ibid 994).
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