The role of tanycytes in hypothalamic glucosensing

Abstract

Tanycytes are elongated hypothalamic glial cells that cover the basal walls of the third ventricle; their apical regions contact the cerebrospinal fluid (CSF), and their processes reach hypothalamic neuronal nuclei that control the energy status of an organism. These nuclei maintain the balance between energy expenditure and intake, integrating several peripheral signals and triggering cellular responses that modify the feeding behaviour and peripheral glucose homeostasis. One of the most important and well-studied signals that control this process is glucose; however, the mechanism by which this molecule is sensed remains unknown. We along with others have proposed that tanycytes play a key role in this process, transducing changes in CSF glucose concentration to the neurons that control energy status. Recent studies have demonstrated the expression and function of monocarboxylate transporters and canonical pancreatic β cell glucose sensing molecules, including glucose transporter 2 and glucokinase, in tanycytes. These and other data, which will be discussed in this review, suggest that hypothalamic glucosensing is mediated through a metabolic interaction between tanycytes and neurons through lactate. This article will summarize the recent evidence that supports the importance of tanycytes in hypothalamic glucosensing, and discuss the possible mechanisms involved in this process. Finally, it is important to highlight that a detailed analysis of this mechanism could represent an opportunity to understand the evolution of associated pathologies, including diabetes and obesity, and identify new candidates for therapeutic intervention.

Glia: silent partners in energy homeostasis and obesity pathogenesis

“…They can be classified into alpha and beta subtypes, each with regional and potentially functional differences [29, 83]. These elongated glial cells simultaneously serve as barrier and conduit cells, with one side of the cell being in contact with the cerebral spinal fluid (CSF) and peripheral circulation through fenestrated capillaries, and the other side being in contact with the hypothalamic parenchyma (Fig.…”

Glial hypothalamic inhibition of GLUT2 expression alters satiety, impacting eating behavior

“…Their apical poles contact the cerebrospinal fluid (CSF), and basal extensions project into the arcuate nucleus (AN) (Flament‐Durand & Brion, 1985). Tanycytes are classified into four main groups on the basis of differences in their anatomical localization and gene expression: α1, α2 (Robins et al, 2013), β1, and β2 (Elizondo‐Vega et al, 2015; Langlet, Mullier, Bouret, Prevot, & Dehouck, 2013). β2‐tanycytes cover the floor of the 3V; in their apical face, they present tight junctions that form the CSF‐median eminence (ME) barrier and extend their projections inside the ME.…”

Hypothalamic Neurogenesis as an Adaptive Metabolic Mechanism

“…In the floor of the 3V, the β2 lateral-tanycytes (β2la) and β2 medial-tanycytes (β2me) are joined by tight junctions forming part of the median eminence (ME)-cerebrospinal fluid (CSF) barrier, and their projections make contact with the fenestrated blood vessels of the ME. Redrawn from a previously published (Elizondo-Vega et al, 2015). …”