Kognitiv funksjon og prestasjon etter simulert nattskift hos rotter kan forklares av endring i døgnrytme, søvnbehov og nivå av stresshormon

Forskere fra Universitetet i Bergen, Washington State University og Universitetet i Groningen har i denne studien undersøkt hvordan simulert skiftarbeid endrer ulike prosesser i hjernen hos rotter. Generelt er det å jobbe nattskift assosiert med økt risiko for ulykker. Ved å bruke en rottemodell for skiftarbeid ønsket forskerne å finne ut hvilke faktorer i hjernen som best kan predikere individuell kognitiv prestasjon under nattskift. Resultatene viser at både endringer i døgnrytmen og søvnbehov gir utslag på prestasjon på en kognitiv oppgave etter simulert nattskift. Markører for hvor plastisk hjernen er kunne forklares med både endringer i døgnrytme, behov for søvn og mengde stresshormon i blodet. Forskerne mener at disse funnene kan åpne opp for nye forskningsområder innen skiftarbeid og hjernehelse.

Cognitive function and brain plasticity in a rat model of shift work: role of daily rhythms, sleep and glucocorticoids

Andrea R. Marti, Torhild T. Pedersen, Jonathan P. Wisor, Jelena Mrdalj, Øystein Holmelid, Sudarshan Patil, Peter Meerlo, Clive R. Bramham, Janne Grønli

Studien er publisert i Scientific Reports

Many occupations require operations during the night-time when the internal circadian clock promotes sleep, in many cases resulting in impairments in cognitive performance and brain functioning. Here, we use a rat model to attempt to identify the biological mechanisms underlying such impaired performance. Rats were exposed to forced activity, either in their rest-phase (simulating night-shift work; rest work) or in their active-phase (simulating day-shift work; active work). Sleep, wakefulness and body temperature rhythm were monitored throughout. Following three work shifts, spatial memory performance was tested on the Morris Water Maze task. After 4 weeks washout, the work protocol was repeated, and blood and brain tissue collected. Simulated night-shift work impaired spatial memory and altered biochemical markers of cerebral cortical protein synthesis. Measures of daily rhythm strength were blunted, and sleep drive increased. Individual variation in the data suggested differences in shift work tolerance. Hierarchical regression analyses revealed that type of work, changes in daily rhythmicity and changes in sleep drive predict spatial memory performance and expression of brain protein synthesis regulators. Moreover, serum corticosterone levels predicted expression of brain protein synthesis regulators. These findings open new research avenues into the biological mechanisms that underlie individual variation in shift work tolerance.