title: Cognitive deficits after systemic induction of inducible nitric oxide synthase: a randomised trial in rats.
abstract: BACKGROUND
  Nitric oxide acts as an important neurotransmitter as well as a sepsis mediator. During sepsis, high levels of nitric oxide, produced by the inducible form of the nitric oxide synthase (iNOS), may lead to disturbances concerning these conflicting roles and cause septic encephalopathy. To evaluate this theory, we aimed at first, to demonstrate cognitive dysfunction in a rat model based on systemic iNOS induction; second, to elucidate molecular mechanisms; and third, to prevent cognitive deficits in our sepsis model.
  
  
  METHODS
  We used a rat systemic inflammation model that is based on the induction of iNOS by heat-killed Corynebacterium parvum in different doses (30 or 60 mg kg). NO2/NO3 plasma levels were measured to prove iNOS induction. Cognitive performance was investigated. In brain tissue, NOS protein and NOS activity were determined. To prevent cognitive deficits, two groups of rats received L-N-(1-Iminoethyl)-lysine (L-NIL), a specific iNOS inhibitor in the drinking water.
  
  
  RESULTS
  The rats[Combining Acute Accent] cognitive performance, that is, short-term memory as well as long-term memory was impaired in C. parvum rats with a peak at the third day after injection in the 60 mg kg group. At the same day, neuronal NOS (nNOS)-protein content in the prefrontal cortex was reduced in C. parvum rats. nNOS activity was also reduced in C. parvum rats. The cognitive deficit in short-term memory could be prevented by L-NIL.
  
  
  CONCLUSIONS
  We demonstrate early, reversible cognitive deficits in a rat model of systemic inflammation with increased systemic iNOS activity. As systemic inhibition of iNOS activity prevented rats from the deficit in short-term memory, an involvement of systemic iNOS induction in this deficit is likely. Whether the reduced nNOS-protein expression and nNOS activity are connected to systemic iNOS induction, however, remains unclear.
authors: Klinik für Anaesthesiologie der Technischen Universität München, Klinikum rechts der Isar, Munich, Germany. b.eckel@lrz.tum.de
authors: Barbara
authors: B
authors: Eckel
authors: Frauke
authors: F
authors: Ohl
authors: Ralph
authors: R
authors: Bogdanski
authors: Eberhard F
authors: EF
authors: Kochs
authors: Manfred
authors: M
authors: Blobner
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology / Q000503:physiopathology; D003072:Cognition Disorders / Q000503:physiopathology*; D004195:Disease Models, Animal; D007249:Inflammation / Q000503:physiopathology*; D008297:Male; D008569:Memory Disorders / Q000503:physiopathology; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000201:enzymology / Q000378:metabolism; D011425:Propionibacterium acnes; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000503:physiopathology*
chemical_list: D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II