Tanycyte, the neuron whisperer.

Reciprocal communication between neurons and glia is essential for normal brain functioning and adequate physiological functions, including energy balance. In vertebrates, the homeostatic process that adjusts food intake and energy expenditure in line with physiological requirements is tightly controlled by numerous neural cell types located within the hypothalamus and the brainstem and organized in complex networks. Within these neural networks, peculiar ependymoglial cells called tanycytes are nowadays recognized as multifunctional players in the physiological mechanisms of appetite control, partly by modulating orexigenic and anorexigenic neurons. Here, we review recent advances in tanycytes' impact on hypothalamic neuronal activity, emphasizing on arcuate neurons.

Tamoxifen Treatment in the Neonatal Period Affects Glucose Homeostasis in Adult Mice in a Sex-Dependent Manner.

Tamoxifen is a selective estrogen receptor modulator used to activate the CREERT2 recombinase, allowing tissue-specific and temporal control of the somatic mutagenesis to generate transgenic mice. Studies integrating development and metabolism require a genetic modification induced by a neonatal tamoxifen administration. Here, we investigate the effects of a neonatal tamoxifen administration on energy homeostasis in adult male and female C57BL/6J mice. C57BL/6J male and female mouse pups received a single injection of tamoxifen 1 day after birth (NTT) and were fed a high-fat/high-sucrose diet at 6 weeks of age. We measured weight, body composition, glucose and insulin tolerance, basal metabolism, and tibia length and weight in adult mice. The neonatal tamoxifen administration exerted long-term, sex-dependent effects on energy homeostasis. NTT female mice became overweight and developed impaired glucose control in comparison to vehicle-treated littermates. NTT females exhibited 60% increased fat mass, increased food intake, decreased physical activity and energy expenditure, impaired glucose and insulin tolerance, and fasting hyperglycemia and hyperinsulinemia. In contrast, NTT male mice exhibited a modest amelioration of glucose and insulin tolerance and long-term decreased lean mass linked to decreased bone weight. These results suggest that the neonatal tamoxifen administration exerted a marked and sex-dependent influence on adult energy homeostasis and bone weight and must therefore be used with caution for the development of transgenic mouse models regarding studies on energy homeostasis and bone biology.