1: Neurotoxicology  2001 Jun;22(3):387-92

Non invasive quantification of manganese deposits in the rat brain by local
measurement of NMR proton T1 relaxation times.

Gallez B, Demeure R, Baudelet C, Abdelouahab N, Beghein N, Jordan B, Geurts M,
Roels HA.

Laboratory of Medicinal Chemistry and Radiopharmacy, Universite catholique de
Louvain, Brussels, Belgium. gallez@cmfa.ucl.ac.be

Up to now, there is no reliable non invasive biomarker for the concentration of
manganese (Mn) in the brain after intoxication to this metal. The aim of the
present experimental study was to determine the predictive value of the
localized measurement of the proton NMR relaxation time T1 as a quantitative
estimation of the concentration of Mn in brain. The relationship of the proton
relaxation rates (1/T1) was established in rat brain homogenates as a function
of the Mn, iron, and copper concentration. Subsequently, an experimental model
of Mn neurotoxicity was used: rats were stereotactically injected with
increasing amounts of Mn2+ (as MnCl2) in the ventricles. After 3 weeks, local
measurements of T1 were carried out in live rats. They were then sacrificed in
order to sample the striatum, the cortex, and the cerebellum from the brain and
to perform a quantitative determination of the concentration of Mn in these
tissues by atomic absorption spectrometry (AAS). The results indicate excellent
correlation coefficients between relaxation rates and tissue Mn concentrations
(r= 0.84, 0.77 and 0.92 for the striatum, the cortex and the cerebellum,
respectively). This methodology offers a unique toolfor monitoring the degree of
Mn concentration in different areas of the brain in animal models of Mn
intoxication. It will be useful for evaluating the efficacy of treatments aimed
at decreasing the metal in the brain. The method could be potentially useful for
being transposed in the clinical situation for monitoring Mn-exposed workers.

PMID: 11456339 [PubMed - indexed for MEDLINE]