Hypothalamic Thyroid Hormone Receptor α1 Signaling Controls Body Temperature.

Area of Science:

• Endocrinology
• Neuroscience
• Thermoregulation

Background:

• Thyroid hormones (THs) are vital for regulating body temperature and metabolism.
• The brain's role in TH-mediated thermoregulation involves specific nuclear receptors, TRα1 and TRβ.
• Precise functions and locations of TR isoforms in temperature control are not fully understood.

Purpose of the Study:

• To investigate the specific roles of TRα1 and TRβ in the central regulation of body temperature.
• To identify the neuroanatomical regions involved in TR-mediated thermoregulation.

Main Methods:

• Utilized mutant TRα1 (TRα1+m) and TRβ knockout mice for radiotelemetry studies.
• Administered oral 3,3',5-triiodothyronine (T3) to assess treatment effects.
• Employed adeno-associated virus (AAV)-mediated expression of dominant-negative TRα1 in the hypothalamus.

Main Results:

• TRβ knockout mice showed no significant impact on body temperature regulation.
• TRα1+m mice exhibited lower body temperature, not fully normalized even at thermoneutral conditions.
• Selective hypothalamic expression of dominant-negative TRα1 reduced body temperature.
• Oral T3 treatment normalized body temperature in TRα1+m mice, indicating an altered central set point.

Conclusions:

• TRα1 signaling within the hypothalamus is essential for maintaining mammalian body temperature.
• Further research is required to elucidate the specific neural pathways and substrates involved.