The ATP-sensitive potassium (KATP) channels are gated by intracellular adenine nucleotides coupling cell metabolism to membrane potential. Channels comprised of Kir6.2 and SUR1 subunits function in subpopulations of mediobasal hypothalamic (MBH) neurons as an essential component of a glucose sensing mechanism in these cells, wherein uptake and metabolism of glucose leads to increase in ATP/ADPic, closure of the channels, and increase in neuronal excitability. However, it is unknown if glucose and/or insulin may also regulate the gene expression of the channel subunits in the brain. The present study investigated if regulation of KATP channel subunit gene expression may be a mechanism by which neuronal populations adapt to prolonged changes in glucose and/or insulin levels in the periphery. Ovariectomized, steroid-replaced rats were fitted with indwelling jugular catheters and infused for 48h with saline, glucose (hyperglycemia-hyperinsulinemia), insulin and glucose (hyperinsulinemia), diazoxide (control), or glucose and diazoxide (hyperglycemia). At the end of infusions the MBH, preoptic area and pituitary were dissected for RNA isolation and RT-PCR. Hyperglycemia decreased Kir6.2 mRNA levels in the MBH, both in the presence and absence of hyperinsulinemia. These same conditions also produced a trend towards decreased SUR1 mRNA levels in the MBH however, it did not exceed statistical significance. Hyperglycemia increased while hyperinsulinemia reduced NPY mRNA levels, when these groups were compared to each other. However, neither was significantly different from values observed in saline-infused controls. In conclusion, hyperglycemia per se may alter expression of KATP channels and thereby induce changes in the excitability of some MBH neurons.