 They may be stimulated by signals such as leptin, alpha-MSH, and catecholamines; and inhibited by glucocorticoids, neuropeptide Y, and agouti-related peptide.In critical illness, inflammation increases tanycyte D2 in the paraventricular nucleus (PVN) of the hypothalamus, leading to local tissue hyperthyroidism.There may also be decreased central D3.