Figure 6.

Hypothyroid Mice Show Diminished STAT-3 Activation upon Leptin Treatment. Phosphorylated STAT3 was visualized by immunohistochemistry in hypothalamic sections of hypothyroid Trhr1/ob dko and MMI-treated ob/ob mice compared with controls. Whereas euthyroid ob/ob and TH-treated Trhr1/ob dko mice showed a strong increase of phospho-STAT3 immunoreactivity upon leptin treatment, the elevation was less pronounced in hypothyroid Trhr1/ob dko and MMI-treated ob/ob mice (A). This diminished response was not due to alterations in STAT3 expression because qPCR analysis of STAT3 expression in the Arc revealed similar transcript levels in euthyroid ob/ob and hypothyroid Trhr1/ob dko mice (B). However, upon leptin treatment, transcript levels of POMC showed a slight decline and transcript levels of AgRP and NPY tended to be elevated in the arcuate nucleus of hypothyroid Trhr1/ob dko mice (B). Scale bar, 100 μm.