Department of Neurobiology, Physiology, and Behavior, University of California, Davis, CA, 95616, USA.
Faculty of Biology, University of Bucharest, Bucharest, Romania.
J Therm Biol. 2024 May;122:103868. doi: 10.1016/j.jtherbio.2024.103868. Epub 2024 Jun 4.
Transient Receptor Potential (TRP) ion channels are important for sensing environmental temperature. In rodents, TRPV4 senses warmth (25-34 °C), TRPV1 senses heat (>42 °C), TRPA1 putatively senses cold (<17 °C), and TRPM8 senses cool-cold (18-26 °C). We investigated if knockout (KO) mice lacking these TRP channels exhibited changes in thermal preference. Thermal preference was tested using a dual hot-cold plate with one thermoelectric surface set at 30 °C and the adjacent surface at a temperature of 15-45 °C in 5 °C increments. Blinded observers counted the number of times mice crossed through an opening between plates and the percentage of time spent on the 30 °C plate. In a separate experiment, observers blinded as to genotype also assessed the temperature at the location on a thermal gradient (1.83 m, 4-50 °C) occupied by the mouse at 5- or 10-min intervals over 2 h. Male and female wildtype mice preferred 30 °C and significantly avoided colder (15-20 °C) and hotter (40-45 °C) temperatures. Male TRPV1KOs and TRPA1KOs, and TRPV4KOs of both sexes, were similar, while female WTs, TRPV1KOs, TRPA1KOs and TRPM8KOs did not show significant thermal preferences across the temperature range. Male and female TRPM8KOs did not significantly avoid the coldest temperatures. Male mice (except for TRPM8KOs) exhibited significantly fewer plate crossings at hot and cold temperatures and more crossings at thermoneutral temperatures, while females exhibited a similar but non-significant trend. Occupancy temperatures along the thermal gradient exhibited a broad distribution that shrank somewhat over time. Mean occupancy temperatures (recorded at 90-120 min) were significantly higher for females (30-34 °C) compared to males (26-27 °C) of all genotypes, except for TRPA1KOs which exhibited no sex difference. The results indicate (1) sex differences with females (except TRPA1KOs) preferring warmer temperatures, (2) reduced thermosensitivity in female TRPV1KOs, and (3) reduced sensitivity to cold and innocuous warmth in male and female TRPM8KOs consistent with previous studies.
瞬时受体电位 (TRP) 离子通道对于感知环境温度很重要。在啮齿动物中， TRPV4 感知温暖（25-34°C），TRPV1 感知热（>42°C），TRPA1 推测感知冷（<17°C），TRPM8 感知凉冷（18-26°C）。我们研究了缺乏这些 TRP 通道的基因敲除（KO）小鼠是否表现出热偏好的变化。使用带有一个热电表面设置在 30°C 和相邻表面温度为 15-45°C 的冷热板来测试热偏好，温度以 5°C 的增量递增。盲法观察者记录小鼠穿过板之间开口的次数和在 30°C 板上的时间百分比。在另一个实验中，对基因型也不知情的观察者也评估了在热梯度（1.83 m，4-50°C）上的位置的温度，在 2 小时内每隔 5 或 10 分钟观察小鼠在该位置的停留时间。雄性和雌性野生型小鼠更喜欢 30°C，明显避免较冷（15-20°C）和较热（40-45°C）的温度。雄性 TRPV1KO 和 TRPA1KO，以及两性的 TRPV4KO 相似，而雌性 WT、TRPV1KO、TRPA1KO 和 TRPM8KO 在整个温度范围内没有表现出明显的热偏好。雄性和雌性 TRPM8KO 没有明显避免最冷的温度。雄性小鼠（除 TRPM8KO 外）在热和冷温度下的板穿越次数显著减少，而在热敏温度下的穿越次数增加，而雌性则表现出相似但不显著的趋势。沿着热梯度的占据温度表现出广泛的分布，随着时间的推移略有收缩。在所有基因型中，除了 TRPA1KO 外，雌性（30-34°C）的平均占据温度（在 90-120 分钟记录）显著高于雄性（26-27°C），而 TRPA1KO 则没有性别差异。结果表明：（1） 雌性（除 TRPA1KO 外）偏爱更温暖温度的性别差异；（2） 雌性 TRPV1KO 的热敏性降低；（3） 雄性和雌性 TRPM8KO 对冷和无害温暖的敏感性降低，与先前的研究一致。
