title: Protein-energy malnutrition induces an aberrant acute-phase response and modifies the circadian rhythm of core temperature.
abstract: Protein-energy malnutrition (PEM), present in 12%-19% of stroke patients upon hospital admission, appears to be a detrimental comorbidity factor that impairs functional outcome, but the mechanisms are not fully elucidated. Because ischemic brain injury is highly temperature-sensitive, the objectives of this study were to investigate whether PEM causes sustained changes in temperature that are associated with an inflammatory response. Activity levels were recorded as a possible explanation for the immediate elevation in temperature upon introduction to a low protein diet. Male, Sprague-Dawley rats (7 weeks old) were fed a control diet (18% protein) or a low protein diet (PEM, 2% protein) for either 7 or 28 days. Continuous core temperature recordings from bioelectrical sensor transmitters demonstrated a rapid increase in temperature amplitude, sustained over 28 days, in response to a low protein diet. Daily mean temperature rose transiently by day 2 (p = 0.01), falling to normal by day 4 (p = 0.08), after which mean temperature continually declined as malnutrition progressed. There were no alterations in activity mean (p = 0.3) or amplitude (p = 0.2) that were associated with the early rise in mean temperature. Increased serum alpha-2-macroglobulin (p < 0.001) and decreased serum albumin (p ≤ 0.005) combined with a decrease in serum alpha-1-acid glycoprotein (p < 0.001) suggest an atypical acute-phase response. In contrast, a low protein diet had no effect on the signaling pathway of the pro-inflammatory transcription factor, NFκB, in the hippocampus. In conclusion, PEM induces an aberrant and sustained acute-phase response coupled with long-lasting effects on body temperature.
authors.affiliation: a College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
authors.forename: Shari E
authors.initials: SE
authors.lastname: Smith
authors.forename: Rafaela Andrade
authors.initials: RA
authors.lastname: Ramos
authors.forename: Roberto
authors.initials: R
authors.lastname: Refinetti
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Farthing
authors.forename: Phyllis G
authors.initials: PG
authors.lastname: Paterson
mesh_terms: D000210:Acute-Phase Reaction; D000818:Animals; D001835:Body Weight; D002940:Circadian Rhythm; D006801:Humans; D011502:Protein-Energy Malnutrition; D017207:Rats, Sprague-Dawley; D013696:Temperature