Nitric Oxide Synthase in Mouse Brain Tissue that Exhibits Alzheimer’s Disease Patrick McCarthy

Introduction Alzheimer’s disease (AD) Future impact Characteristics: Beta-amyloid plaque

Introduction Transgenic mouse model of Alzheimer’s disease using species, Mus musculus Two genetically engineered mouse types: - Transgenic positive (Tg. +): with AD-expressing gene - Transgenic negative (Tg. -): without AD-expressing gene

Introduction Nitric oxide synthase (NOS) - Enzyme throughout body 1989, NOS in brains - Bredt et al. Early 2000s, NOS and AD relation strongly showed - de La Torre et al., Law et al.

NOS-catalyzed production of NO via L-arginine to L-citrulline pathway L-arginine L-citrulline NOS

Introduction Three NOS isoforms - neuronal NOS (nNOS) - endothelial NOS (eNOS) - inducible NOS (iNOS)

Hypothesis (1) Luth et al. found iNOS and eNOS activity increased in AD Luth et. al and Quinn et. al found nNOS activity increased in AD First hypothesis: total NOS activity increased in AD brains

Hypothesis (2) Norris et al. found number of nNOS- containing neurons decreased Fewer neurons, less total concentration of nNOS Second hypothesis: nNOS concentrations in AD brains were lower

Procedure Tissue preparation Determining activity - Spectrophotometer to assay

Results NOS activity significantly different (p = 0.014) Tg. + NOS activity 58 % greater than Tg. -

Procedure Concentrations - Slot Blot - Western Blot

Results Tg. + Tg. - Intensity of band corresponds to concentrations Darker band, higher concentration This test inconclusive

Procedure Concentrations -ELISA assay

Results nNOS concentrations significantly different (p = 0.008) Tg. + 36% less nNOS concentration than Tg. -

Conclusion (1) Total NOS was increased in Tg. + brains (2) Concentrations of nNOS lower in Tg. + brains

Conclusion Suggest neurons initially damaged or further degenerated by the toxicity of the free radical NO Increase in NOS activity can most likely be attributed to increase in nNOS and/or eNOS Support the role of NOS and nNOS in AD

Potential Future Studies Find concentrations of other two isoforms of NOS, iNOS and eNOS Use different-aged brains to study the role of NOS activity and concentration before, during, and after the onset of AD Further test certain areas of the brain (human and mice) to investigate role in AD

Acknowledgements Dr. Ian Armitage and Dr. Bruce Martin Abigail Tolkheim and rest of the Armitage Lab team Ms. Lois Fruen Team Research

The Role of Nitric Oxide Synthase in Alzheimer’s Disease Patrick McCarthy