Total parenteral nutrition entrains the central and peripheral circadian clocks

The administration schedule of total parenteral nutrition (TPN) ignores the human physiological food-intake rhythm. This study examined the effects of TPN on the central and peripheral circadian clocks. Male Wistar rats were divided into a control group, a nocturnal-TPN group, and a diurnal-TPN group. On the seventh day after TPN administration, expression of rat period2 (rPer2) and D-site binding protein (rDBP) mRNA were measured in the suprachiasmatic nucleus (SCN) and liver. While rPer2 and rDBP mRNA expression of the nocturnal-TPN rats showed similar oscillation patterns to those in the free-fed control rats both in the SCN and liver, they were shifted significantly in the diurnal-TPN rats. This phase shift occurred as early as day 1. TPN, which ignores physiological food-intake rhythms, alters the rhythm of the central and peripheral clocks.