Altered thermal selection behavior in mice lacking transient receptor potential vanilloid 4

Area of Science:

• Neuroscience
• Physiology
• Sensory Biology

Background:

• Transient receptor potential vanilloid 4 (TRPV4) is a cation channel activated by hypotonicity and warm temperatures.
• TRPV4 knockout (TRPV4-/-) mice show deficits in inflammation-induced thermal hyperalgesia.
• The role of TRPV4 in normal warmth perception, independent of injury, remains unclear.

Purpose of the Study:

• To investigate the contribution of TRPV4 to thermosensation and thermoregulation in vivo.
• To determine if TRPV4 is necessary for normal warmth perception under non-inflammatory conditions.

Main Methods:

• Utilized TRPV4 knockout (TRPV4-/-) and wild-type (WT) littermate mice.
• Assessed thermal preference using a thermal gradient.
• Measured withdrawal latencies during acute tail heating.
• Evaluated behavioral responses to paw inflammation on a thermal gradient.
• Monitored circadian body temperature fluctuations and thermoregulation in a warm environment.

Main Results:

• TRPV4-/- mice selected significantly warmer temperatures on a thermal gradient compared to WT mice.
• TRPV4-/- mice demonstrated a preference for 34°C, unlike WT mice which could not discriminate between 30°C and 34°C.
• TRPV4-/- mice exhibited prolonged withdrawal latencies in acute tail heating tests.
• Behavioral responses to paw inflammation and thermoregulation were similar between TRPV4-/- and WT mice.

Conclusions:

• TRPV4 is required for normal thermal responsiveness and warmth perception in vivo.
• TRPV4 plays a crucial role in sensing innocuous warmth under non-injury conditions.
• TRPV4's function in thermal sensation is distinct from its role in inflammation-induced hyperalgesia and general thermoregulation.