Abstract

Our data proposes that glucose is transferred directly to the cerebrospinal fluid (CSF) of the hypothalamic ventricular cavity through a rapid fast-track-type mechanism that would efficiently stimulate the glucosensing areas. This mechanism would occur at the level of the median eminence (ME), a periventricular hypothalamic zone with no blood-brain barrier. This fast-track mechanism would involve specific glial cells of the ME known as beta 2 tanycytes that could function as inverted enterocytes, expressing low-affinity glucose transporters GLUT2 and GLUT6 in order to rapidly transfer glucose to the CSF. Due to the large size of tanycytes, the presence of a high concentration of mitochondria and the expression of low-affinity glucose transporters, it would be expected that these cells accumulate glucose in the endoplasmic reticulum (ER) by sequestering glucose-6-phosphate (G-6-P), in a similar way to that recently demonstrated in astrocytes. Glucose could diffuse through the cells by micrometric distances to be released in the apical region of beta 2 tanycytes, towards the CSF. Through this mechanism, levels of glucose would increase inside the hypothalamus, stimulating glucosensing mechanisms quickly and efficiently.Key messages center dot Glucose diffuses through the median eminence cells (beta 2 tanycytes), towards the hypothalamic CSF.center dot Glucose is transferred through a rapid fast-track-type mechanism via GLUT2 and GLUT6.center dot Through this mechanism, hypothalamic glucose levels increase, stimulating glucosensing.