Tanycytes and a differential fatty acid metabolism in the hypothalamus

Hofmann, Kristina; Lamberz, Christian; Piotrowitz, Kira; Offermann, Nina; But, Diana; Scheller, Anja; Al‐Amoudi, Ashraf; Kuerschner, Lars

doi:10.1002/glia.23088

Cited by 40 publications

(49 citation statements)

References 70 publications

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“…These antecedents suggest that tanycytes are responsible for detecting changes in glucose concentration from the CSF and generating a signal that allows the generation of a response by the adjacent neuron, forming a circuit that involves both cell types in a coupled manner. On the other hand increased lipid droplet content in tanycytes has been observed after a prolonged high fat diet (Hofmann et al, 2017), which is in agreement with a role of tanycytes in hypothalamic lipid sensing (Levin, Magnan, Dunn-Meynell, & Le Foll, 2011). Thus, due to their localization in the hypothalamus, tanycytes are in a privileged position to detect hormonal, nutritional and mitogenic signals released by peripheral organs or present in the CSF.…”

supporting

confidence: 72%

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

Barahona

Llanos

Recabal

et al. 2017

Glia

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Glucose is a key modulator of feeding behavior. By acting in peripheral tissues and in the central nervous system, it directly controls the secretion of hormones and neuropeptides and modulates the activity of the autonomic nervous system. GLUT2 is required for several glucoregulatory responses in the brain, including feeding behavior, and is localized in the hypothalamus and brainstem, which are the main centers that control this behavior. In the hypothalamus, GLUT2 has been detected in glial cells, known as tanycytes, which line the basal walls of the third ventricle (3V). This study aimed to clarify the role of GLUT2 expression in tanycytes in feeding behavior using 3V injections of an adenovirus encoding a shRNA against GLUT2 and the reporter EGFP (Ad‐shGLUT2). Efficient in vivo GLUT2 knockdown in rat hypothalamic tissue was demonstrated by qPCR and Western blot analyses. Specificity of cell transduction in the hypothalamus and brainstem was evaluated by EGFP‐fluorescence and immunohistochemistry, which showed EGFP expression specifically in ependymal cells, including tanycytes. The altered mRNA levels of both orexigenic and anorexigenic neuropeptides suggested a loss of response to increased glucose in the 3V. Feeding behavior analysis in the fasting‐feeding transition revealed that GLUT2‐knockdown rats had increased food intake and body weight, suggesting an inhibitory effect on satiety. Taken together, suppression of GLUT2 expression in tanycytes disrupted the hypothalamic glucosensing mechanism, which altered the feeding behavior.

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supporting

confidence: 72%

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

Barahona

Llanos

Recabal

et al. 2017

Glia

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“…In diet-induced obesity, the amount of lipid droplets increase considerably in tanycytes (Hofmann et al, 2017). Moreover, the ratio between saturated and unsaturated lipids is modified suggesting that this cell type may also act as a sensor and gatekeeper for lipids in the median eminence/ARC interface (Hofmann et al, 2017). …”

Section: Bbb In the Hypothalamic Areamentioning

confidence: 99%

Development and Function of the Blood-Brain Barrier in the Context of Metabolic Control

et al. 2017

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Under physiological conditions, the brain consumes over 20% of the whole body energy supply. The blood-brain barrier (BBB) allows dynamic interactions between blood capillaries and the neuronal network in order to provide an adequate control of molecules that are transported in and out of the brain. Alterations in the BBB structure and function affecting brain accessibility to nutrients and exit of toxins are found in a number of diseases, which in turn may disturb brain function and nutrient signaling. In this review we explore the major advances obtained in the understanding of the BBB development and how its structure impacts on function. Furthermore, we focus on the particularities of the barrier permeability in the hypothalamus, its role in metabolic control and the potential impact of hypothalamic BBB abnormities in metabolic related diseases.

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“…This suggests further possible mechanisms, whereby tanycytes mediate neuronal responses in the hypothalamus to changes in peripheral carbohydrate and fat metabolism (23, 24). Recently, a metabolic link between tanycytes and astrocytes, likely to impact hypothalamic lipid sensing, has been suggested (25). In addition, in leptin receptor deficient mice ( db/db ) and in mice treated with a leptin antagonist, leptin accumulates in the median eminence but fails to appear in the mediobasal hypothalamus, providing evidence that leptin’s signaling cascade begins in tanycytes in the median eminence, and then transitions to hypothalamic nuclei and neurons (26).…”

Section: Hypothalamic Tanycytes As Mediators Of Energy Homeostasismentioning

confidence: 99%

Tanycytes As Regulators of Seasonal Cycles in Neuroendocrine Function

Lewis

Ebling

2017

Front. Neurol.

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Annual cycles of physiology and behavior are highly prevalent in organisms inhabiting temperate and polar regions. Examples in mammals include changes in appetite and body fat composition, hibernation and torpor, growth of antlers, pelage and horns, and seasonal reproduction. The timing of these seasonal cycles reflects an interaction of changing environmental signals, such as daylength, and intrinsic rhythmic processes: circannual clocks. As neuroendocrine signals underlie these rhythmic processes, the focus of most mechanistic studies has been on neuronal systems in the hypothalamus. Recent studies also implicate the pituitary stalk (pars tuberalis) and hypothalamic tanycytes as key pathways in seasonal timing. The pars tuberalis expresses a high density of melatonin receptors, so is highly responsive to changes in the nocturnal secretion of melatonin from the pineal gland as photoperiod changes across the year. The pars tuberalis in turn regulates tanycyte function in the adjacent hypothalamus via paracrine signals. Tanycytes are radial glial cells that persist into adulthood and function as a stem cell niche. Their cell soma are embedded in the ependymal lining of the third ventricle, and they also send elaborate projections through the arcuate nucleus, many of which terminate on capillaries in the median eminence. This anatomy underlies their function as sensors of nutrients in the circulation, and as regulators of transport of hormones and metabolites into the hypothalamus. In situ hybridization studies reveal robust seasonal changes in gene expression in tanycytes, for example, those controlling transport and metabolism of thyroid hormone and retinoic acid. These hormonal signals play a key role in the initial development of the brain, and experimental manipulation of thyroid hormone availability in the adult hypothalamus can accelerate or block seasonal cyclicity in sheep and Siberian hamsters. We hypothesize that seasonal rhythms depends upon reuse of developmental mechanisms in the adult hypothalamus and that tanycytes are key orchestrators of these processes.

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Tanycytes and a differential fatty acid metabolism in the hypothalamus

Cited by 40 publications

References 70 publications

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

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

Development and Function of the Blood-Brain Barrier in the Context of Metabolic Control

Tanycytes As Regulators of Seasonal Cycles in Neuroendocrine Function

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