G6PC1 and Hyperglycemia: In addition, the down-regulation of the hepatic gluconeogenic gene Pck1 observed in L6 rats would neither be in agreement with the hyperglycemia displayed by these animals, since in mice exposed to disrupted daily light-dark cycles this metabolic feature was accompanied by an increase in the mRNA levels of Pck1 and G6pc in liver (Oishi and Itoh, 2013).