title: Interleukin-1beta-induced reduction of tissue water diffusion in the juvenile rat brain on ADC MRI is not associated with (31)P MRS-detectable energy failure.
abstract: BACKGROUND
  It has long been known that an intrastriatal microinjection of the archetypal pro-inflammatory cytokine, interleukin-1beta (IL-1β), in juvenile rats induces a chronic reduction in the apparent diffusion coefficient (ADC) of tissue water on magnetic resonance imaging (MRI). Reduced ADC during acute cerebral ischaemia is an established indicator of metabolic failure whereas the cause of the IL-1β-induced reduction remains to be deciphered. Previously, it has been shown that IL-1β does not perturb the phosphorus ((31)P) magnetic resonance spectroscopy (MRS)-detectable energy status of an ex vivo preparation of rat brain parenchyma that is devoid of a functional vasculature component. However, brain energy status following an IL-1β challenge in vivo remains to be examined.
  
  
  METHODS
  This study is the first longitudinal in vivo examination of the correlation of ADC MRI with localised (31)P MRS signals obtained specifically from within the injected and non-injected striatum following IL-1β (1 ng/ul or 100 ng/ul) challenge, in real-time.
  
  
  RESULTS
  Despite observing a chronic reduction in ADC at either dose of IL-1β challenge, energy compromise was not detected at any time point.
  
  
  CONCLUSIONS
  The IL-1β-induced effects pertaining to a functional vasculature such as leukocyte recruitment, blood-brain barrier (BBB) breakdown and blood flow changes are unlikely to impact on overall tissue energy status. Compared to classic ischaemia, there is dissociation between ADC and energy status within an IL-1β-induced lesion in vivo.
authors.affiliation: MRC Biochemical and Clinical Magnetic Resonance Unit, Department of Biochemistry, South Parks Road, University of Oxford, OX1 3QU, Oxford, UK.
authors.forename: Raman
authors.initials: R
authors.lastname: Saggu
keywords: Apparent diffusion coefficient; Brain; Energy metabolism; Interleukin-1beta; Magnetic resonance imaging; Phosphorus magnetic resonance spectroscopy