The cold‐sensing ion channel TRPM8 regulates central and peripheral clockwork and the circadian oscillations of body temperature. (31st October 2022)

• Record Type: Journal Article
• Authors: Reimúndez, Alfonso; Fernández‐Peña, Carlos; Ordás, Purificación; Hernández‐Ortego, Pablo; Gallego, Rosalía; Morenilla‐Palao, Cruz; Navarro, Juan; Martín‐Cora, Francisco; Pardo‐Vázquez, José Luís; Schwarz, Lindsay A.; Arce, Victor; Viana, Félix; Señarís, Rosa
• Is Part Of: Acta physiologica. Volume 237:Number 3(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-31
• Subjects: body temperature -- central and peripheral clocks -- circadian regulation -- sensory physiology -- TRPM8; Physiology -- Periodicals; Physiology -- Research -- Periodicals; 612
• DOI: 10.1111/apha.13896
• Languages: English
• ISSNs: 1748-1708

Abstract

Abstract: Aim: Physiological functions in mammals show circadian oscillations, synchronized by daily cycles of light and temperature. Central and peripheral clocks participate in this regulation. Since the ion channel TRPM8 is a critical cold sensor, we investigated its role in circadian function. Methods: We used TRPM8 reporter mouse lines and TRPM8‐deficient mice. mRNA levels were determined by in situ hybridization or RT‐qPCR and protein levels by immunofluorescence. A telemetry system was used to measure core body temperature (Tc). Results: TRPM8 is expressed in the retina, specifically in cholinergic amacrine interneurons and in a subset of melanopsin‐positive ganglion cells which project to the central pacemaker, the suprachiasmatic nucleus (SCN) of the hypothalamus. TRPM8‐positive fibres were also found innervating choroid and ciliary body vasculature, with a putative function in intraocular temperature, as shown in TRPM8‐deficient mice. Interestingly, Trpm8 −/− animals displayed increased expression of the clock gene Per 2 and vasopressin (AVP) in the SCN, suggesting a regulatory role of TRPM8 on the central oscillator. Since SCN AVP neurons control body temperature, we studied Tc in driven and free‐running conditions. TRPM8‐deficiency increased the amplitude of Tc oscillations and, under dim constant light, induced a greater phase delay and instability of Tc rhythmicity. Finally, TRPM8‐positive fibres innervate peripheral organs, like liver and white adipose tissue. Notably, Trpm8 −/− mice displayed a dysregulated expression of Per 2 mRNA in these metabolic tissues. Conclusion: Our findings support a function of TRPM8 as a temperature sensor involved in the regulation of central and peripheral clocks and the circadian control of Tc.