Figure 3:

Pituitary glycoprotein hormone receptors, GLUT2, and leptin receptors are found in 3V tanycytes. Thyroid-stimulating hormone (TSH) is stimulated and secreted in response to the hypothalamic thyrotropin-releasing hormone (TRH). The conversion of thyroxine to triiodothyronine (T₃) occurs in the tanycytes, and this process is thought to be the critical regulator of the TRH neurons. In turn, T₃ itself has been reported to have orexigenic properties. Tanycytes express the glucose transporter GLUT2 and glycolytic enzyme GCK, which is a critical enzymatic component of glucosensing. Additionally, the adipokine leptin acts via LEPR found on the ME tanycytes to regulate appetite and energy expenditure. We also found expression of FSHRs, LHCGRs, and OXTRs in 3V tanycytes, but their functions are currently unknown. 3V, third ventricle; ARC, arcuate nucleus; DIO2, iodothyronine deiodinase 2; FSHR, follicle-stimulating hormone receptor; GCK, glucokinase; GLUT2, glucose transporter 2; LDH, lactate dehydrogenase; LEPR, leptin receptor; LHCGR, luteinizing hormone/choriogonadotropin receptor; MCT1/4, lactate transporter 1 and 4; ME, median eminence; OXTR, oxytocin receptor; POMC, proopiomelanocortin; T₃, triiodothyronine; T₄, l-thyroxine; TSH, thyroid-stimulating hormone; TSHR, thyroid-stimulating hormone receptor.