Modelling the protein-energy malnourished stroke patient
Andrade Ramos, Rafaela
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Little is known about the effects of protein-energy malnutrition (PEM) developing after stroke on brain recovery. The goal of this project was to develop two experimental models in the adult rat to allow evaluation of nutritional effects on post-stroke recovery: (1) a PEM model, and (2) a photothrombotic stroke model. Experiment 1 examined the hypothesis that a diet containing either 1% or 0.5% protein will produce an acute state of mild-moderate PEM in adult rats. Male, Sprague-Dawley rats (16 wk) were trained in the Montoya staircase before being randomized to diets containing 0.5% (n=8), 1% (n=8), or 12.5% protein (n=10 [CON]) for 31d. Both low protein diets increased liver lipid content (p< 0.001) and decreased food intake (p= 0.005) and body weight (p< 0.001) compared to the 12.5% protein diet. The 0.5% protein group best mimicked the stroke patient, as judged by decreased serum albumin (p= 0.018) and an acute decrease in mean (±SEM) body weight (g) by d7 (0.5%= 424±15; 1%= 428±14; CON= 477±10; p = 0.011). Increased concentrations of the positive acute phase proteins, alpha-2-macroglobulin and alpha-1-acid glycoprotein, were greatest in the 0.5% group (p< 0.001). No differences were observed in the Montoya test on d3, 15, or 30 (p= 0.26). Values on d30 were: 0.5%= 109.5±4.4% of pre-diet performance; 1%= 97.2±5.5%; CON= 98.5±10.2%. Experiment 2 tested the hypothesis that targeted laser irradiation and 30 mg/kg of rose Bengal injection will cause an infarct in the forepaw region of the cortex with accompanying functional deficits. Male adult rats trained in the Montoya staircase were randomized to ISCHEMIA (n=15) or SHAM (n=3) surgery. A cortical infarct occurred in 86% of rats, with some misplacement and variability in volume (5.7-12.8 mm3). Forepaw impairments were confirmed by decreased performance in the staircase at d3 (34.3±7.3 % of pre-stroke performance, p<0.001) and diminished use in the cylinder test (30.3±4.0% affected limb use versus 53.9±1.93% prestroke, p< 0.001). At d30, mean recovery was incomplete in the staircase (p< 0.001). These experimental models, with additional refinements, can be used to address the hypothesis that deteriorating nutritional status after a stroke interferes with brain recovery.
DegreeMaster of Science (M.Sc.)
SupervisorPaterson, Phyllis G.
CommitteeMuir, Gillian; Whiting, Susan; Bandy, Brian
Copyright DateJune 2013