EFFECTS OF PROTEIN-ENERGY MALNUTRITION ON SPONTANEOUS MOTOR RECOVERY AFTER STROKE

Abstract

The development of comorbidity factors such as malnutrition may compromise functional recovery following stroke. The objectives of this study were to elucidate the effects of post-stroke protein-energy malnutrition (PEM) on infarct size, spontaneous motor recovery, and the acute phase response in the chronic period. Adult, male (12 week old) Sprague-Dawley rats were trained for at least 14 days in the Montoya staircase. Food intake was monitored daily and body weight was recorded weekly. Just prior to inducing stroke, rats were tested in the cylinder and Montoya staircase to determine baseline values for forelimb use during spontaneous exploration and skilled reaching, respectively. These animals were then subjected to photothrombotic stroke targeted to the motor cortex or sham surgery. Animals were tested in the cylinder on day 4 after surgery, before assignment to either control diet (12.5 % protein) or PEM (0.5 % protein) (n= 6-9/experimental group), and again on days 16 and 29. The staircase was abandoned for post-stroke testing because training criteria were not met. On Day 30, blood, brain, and liver were collected for biochemical or histological analysis. Feeding the low protein diet resulted in PEM as measured by decreased body weight p<0.001), food intake (p=0.016), and serum albumin (p<0.001) and increased liver lipid (p<0.001) and serum A2M (p=0.001). Both stroke (p=0.016) and PEM (p=0.001) elicited increases in the positive acute phase protein, A2M. The effect of PEM on post-stroke cylinder performance varied by specific endpoint. PEM exacerbated forelimb asymmetry during vertical exploration on Days 16 and 29 when scored by method 1 (p≤ 0.024), and this was not due to a change in infarct size (p=0.775). Scoring exploration by method 2 and initiation of exploration by first touch demonstrated similar patterns for preferred limb use after stroke, although these endpoints were not significantly affected by PEM (p≥0.301). The score for takeoff to initiate exploration was also impaired by stroke (p<0.001), but PEM had no influence (p=0.463). Termination of exploration (landing) was not influenced by stroke (p=0.332), and there was no independent effect of PEM (p=0.959).