Hindbrain lactate regulates preoptic gonadotropin-releasing hormone (GnRH) neuron GnRH-I protein but not AMPK responses to hypoglycemia in the steroid-primed ovariectomized female rat.

•The luteinizing hormone (LH) surge is repressed by caudal hindbrain metabolic signaling.•Insulin plus hindbrain lactate infusion normalizes positive-feedback-induced LH secretion.•Lactate reverses hypoglycemic effects on markers of A2 nerve cell function.•Lactate status regulates A2 MCT2 and GLUT3 substrate fuel transporter expression.•Lactate regulates GnRH neuron neuropeptide synthesis, but not AMPK activity.