TRPM8 Channels Research Articles

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.1

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.1

Pathophysiological Roles of Transient Receptor Potential (Trp) Channels and Zinc Toxicity in Brain Disease.

Maintaining the correct ionic gradient from extracellular to intracellular space via several membrane-bound transporters is critical for maintaining overall cellular homeostasis. One of these transporters is the transient receptor potential (TRP) channel family that consists of six putative transmembrane segments systemically expressed in mammalian tissues. Upon the activation of TRP channels by brain disease, several cations are translocated through TRP channels. Brain disease, especially ischemic stroke, epilepsy, and traumatic brain injury, triggers the dysregulation of ionic gradients and promotes the excessive release of neuro-transmitters and zinc. The divalent metal cation zinc is highly distributed in the brain and is specifically located in the pre-synaptic vesicles as free ions, usually existing in cytoplasm bound with metallothionein. Although adequate zinc is essential for regulating diverse physiological functions, the brain-disease-induced excessive release and translocation of zinc causes cell damage, including oxidative stress, apoptotic cascades, and disturbances in energy metabolism. Therefore, the regulation of zinc homeostasis following brain disease is critical for the prevention of brain damage. In this review, we summarize recent experimental research findings regarding how TRP channels (mainly TRPC and TRPM) and zinc are regulated in animal brain-disease models of global cerebral ischemia, epilepsy, and traumatic brain injury. The blockade of zinc translocation via the inhibition of TRPC and TRPM channels using known channel antagonists, was shown to be neuroprotective in brain disease. The regulation of both zinc and TRP channels may serve as targets for treating and preventing neuronal death.

Bitter taste cells in the ventricular walls of the murine brain regulate glucose homeostasis

The median eminence (ME) is a circumventricular organ at the base of the brain that controls body homeostasis. Tanycytes are its specialized glial cells that constitute the ventricular walls and regulate different physiological states, however individual signaling pathways in these cells are incompletely understood. Here, we identify a functional tanycyte subpopulation that expresses key taste transduction genes including bitter taste receptors, the G protein gustducin and the gustatory ion channel TRPM5 (M5). M5 tanycytes have access to blood-borne cues via processes extended towards diaphragmed endothelial fenestrations in the ME and mediate bidirectional communication between the cerebrospinal fluid and blood. This subpopulation responds to metabolic signals including leptin and other hormonal cues and is transcriptionally reprogrammed upon fasting. Acute M5 tanycyte activation induces insulin secretion and acute diphtheria toxin-mediated M5 tanycyte depletion results in impaired glucose tolerance in diet-induced obese mice. We provide a cellular and molecular framework that defines how bitter taste cells in the ME integrate chemosensation with metabolism.

Bilirubin gates the TRPM2 channel as a direct agonist to exacerbate ischemic brain damage

Stroke prognosis is negatively associated with an elevation of serum bilirubin, but how bilirubin worsens outcomes remains mysterious. We report that post-, but not pre-, stroke bilirubin levels among inpatients scale with infarct volume. In mouse models, bilirubin increases neuronal excitability and ischemic infarct, whereas ischemic insults induce the release of endogenous bilirubin, all of which are attenuated by knockout of the TRPM2 channel or its antagonist A23. Independent of canonical TRPM2 intracellular agonists, bilirubin and its metabolic derivatives gate the channel opening, whereas A23 antagonizes it by binding to the same cavity. Knocking in a loss of binding point mutation for bilirubin, TRPM2-D1066A, effectively antagonizes ischemic neurotoxicity in mice. These findings suggest a vicious cycle of stroke injury in which initial ischemic insults trigger the release of endogenous bilirubin from injured cells, which potentially acts as a volume neurotransmitter to activate TRPM2 channels, aggravating Ca2+-dependent brain injury.

The TRPM7 channel reprograms cellular glycolysis to drive tumorigenesis and angiogenesis

Cancer or endothelial cells preferably catabolize glucose through aerobic glycolysis rather than oxidative phosphorylation. Intracellular ionic signaling has been shown to regulate glucose metabolism, but the underlying ion channel has yet to be identified. RNA-seq, metabolomics and genetic assay revealed that the TRPM7 channel regulated cellular glycolysis. Deletion of TRPM7 suppressed cancer cell glycolysis and reduced the xenograft tumor burden. Deficiency of endothelial TRPM7 inhibited postnatal retinal angiogenesis in mice. Mechanistically, TRPM7 transcriptionally regulated the solute carrier family 2 member 3 (SLC2A3, also known as GLUT3) via Ca2+ influx-induced calcineurin activation. Furthermore, CREB-regulated transcription coactivator 2 (CRTC2) and CREB act downstream of calcineurin to relay Ca2+ signal to SLC2A3 transcription. Expression of the constitutively active CRTC2 or CREB in TRPM7 knockout cell normalized glycolytic metabolism and cell growth. The TRPM7 channel represents a novel regulator of glycolytic reprogramming. Inhibition of the TRPM7-dependent glycolysis could be harnessed for cancer therapy.

Low molecular weight heparin treatment reduced apoptosis and oxidative cytotoxicity in the thrombocytes of patients with recurrent pregnancy loss and thrombophilia: Involvements of TRPM2 and TRPV1 channels.

Recurrent pregnancy loss (RPL) is known to be associated with increased thrombophilia and oxidative toxicity. However, the mechanism of thrombophilia apoptosis and oxidative toxicity is still unclear. In addition, the treatment of heparin induced regulator roles on intracellular free Ca2+ ([Ca2+ ]i ) and cytosolic reactive oxygen species (cytROS) concentrations in several diseases. TRPM2 and TRPV1 channels are activated by different stimuli, including oxidative toxicity. Theaim of this study was to investigate the effects of low molecular weight heparin (LMWH) via modulation of TRPM2 and TRPV1 on calcium signaling, oxidative toxicity, and apoptosis in the thrombocytes of RPL patients. Thrombocyte and plasma samples collected from 10 patients with RPL and 10 healthy controls were used in the currentstudy. The [Ca2+ ]i concentration, cytROS (DCFH-DA), mitochondrial membrane potential (JC-1), apoptosis, caspase-3, and caspase-9 levelswere high in the plasma and thrombocytesof RPL patients, although they were diminished by the treatments of LMWH, TRPM2 (N-(p-amylcinnamoyl)anthranilic acid) and TRPV1 (capsazepine) channel blockers. The current study results suggest that the treatment of LMWH is useful against apoptotic cell death and oxidative toxicity in the thrombocytes of patients with RPL, which seem to be dependent on increased levels of [Ca2+ ]i concentrationvia the activation of TRPM2 and TRPV1.

On the modulation of TRPM channels: Current perspectives and anticancer therapeutic implications.

The transient melastatin receptor potential (TRPM) ion channel subfamily functions as cellular sensors and transducers of critical biological signal pathways by regulating ion homeostasis. Some members of TRPM have been cloned from cancerous tissues, and their abnormal expressions in various solid malignancies have been correlated with cancer cell growth, survival, or death. Recent evidence also highlights the mechanisms underlying the role of TRPMs in tumor epithelial-mesenchymal transition (EMT), autophagy, and cancer metabolic reprogramming. These implications support TRPM channels as potential molecular targets and their modulation as an innovative therapeutic approach against cancer. Here, we discuss the general characteristics of the different TRPMs, focusing on current knowledge about the connection between TRPM channels and critical features of cancer. We also cover TRPM modulators used as pharmaceutical tools in biological trials and an indication of the only clinical trial with a TRPM modulator about cancer. To conclude, the authors describe the prospects for TRPM channels in oncology.

Phosphorus magnesium fiber regulates macrophage polarization through TRPM7 to accelerate wound healing

Wound healing is a complex process that can be delayed by persistent inflammatory responses after trauma. Many studies have found that in situ application of biomaterials releases metal ions into wounds to promote wound healing, but the underlying mechanism has not been elucidated. Therefore, we developed a novel nanoscale functional material, phosphorus magnesium fiber (PMF), as a wound dressing to explore its association with wound healing. In this study, in vivo wound healing results showed that PMF accelerated wound closure in full-thickness wound animal models, accompanied by collagen deposition and granulation formation. Moreover, PMF accelerated macrophage polarization by regulating TRPM7-ERK1/2 signaling through the long-term release of magnesium ions into the wound, which contributes to enhancing cell proliferation, growth factor production, and synthesis of ECM in the wound bed, ultimately facilitating wound healing. In vitro studies revealed that PMF promoted the polarization of macrophages to the anti-inflammatory M2 phenotype. Meanwhile, PMF up-regulated TRPM7-ERK1/2 expression. In conclusion, our study confirmed the relationship between PMF and macrophage behavior mediated by the TRPM7 channel protein and subsequently investigated the function of PMF in wound healing. This magnesium-based nanofiber material offers an innovative method for treating open wounds and is anticipated to be used as a wound dressing in the field of tissue regeneration.

Abstract WP240: TRPM2 Channel Deletion In Neurons Reduces Injury Following Ischemic Stroke And Improves Post-stroke Cognitive Function

Background: Emerging evidence implicates post-stroke cognitive impairment as a major contributor to long-term disability. Therefore, optimal therapeutic targets reduce acute ischemic injury and enhance post-stroke brain function. Strong data demonstrates that a novel TRPM2 channel antagonist (tat-M2NX) provides neuroprotection and improves synaptic function, thereby reducing post-stroke cognitive impairment (PSCI). Hypothesis: Knockout of neuron-specific TRPM2 channel expression reduces infarct volume and enhances functional recovery following MCAO Methods: Transient MCAO (60 min) was performed on adult (8-10 week) male and female TRPM2 neuron-specific KO (TRPM2fl/fl, CaMKII Cre) and TRPM2 floxed controls (TRPM2fl/fl)Hemispheric infarct volume analyzed from MRI (T2) images 3 days post-injury by a blinded investigator. Extracellular field recordings of CA1 neurons were performed in acute hippocampal slices prepared 7 days after recovery from MCAO to analyze synaptic placticity (LTP). Results: We observed that neuronal-specific TRPM2 channel knockout reduces acute ischemic injury (infarct volume) in male animals, while having minimal effect on female mice. Consistent with the hypothesis that neuronal TRPM2 channels contribute to ischemia-induced synaptic dysfunction, recordings obtained in brain slices from neuronal TRPM2 channel KO mice (TRPM2fl/fl-CaMKII CRE) mice 7 days after recovery from 60 min MCAo exhibited intact hippocampal plasticity compared to control TRPM2fl/fl mice not expressing CRE. Male sham control mice exhibit robust LTP of 163±10.4% (n=3) compared to 115±5.6% (n=4) in TRPM2fl/fl mice after MCAO. Neuronal KO exhibited 175±9.8% (n=2). Similarly, female mice had control LTP of 170±6.8% (n=4) compared to 125±6.8% (n=3) in TRPM2fl/fl mice after MCAO. Neuronal KO exhibited 208±7.8% (n=5, p<0.05 ANOVA compared to TRPM2fl/fl MCAO). Conclusion: Our data highlight that TRPM2 channels expressed in neurons contribute to both acute injury following transient ischemic stroke and subacute/chronic functional recovery.

Exploring functional conservation of the cooling agent binding site in the transient receptor potential melastatin subfamily.

Transient Receptor Potential (TRP) cation channels act as cellular sensors of a wide variety of stimuli and play a role in many biological processes, making them attractive pharmacological targets. However, the lack of specific agonists or antagonists for many subfamily members has impeded studies of both their biophysical properties and their broader biological functions. The architecture of the TRP channel transmembrane domain, which contains both the ion conducting pore and several ligand binding sites, is conserved across the family, and previous studies transferring ligand sensitivity among TRP channels revealed conserved channel gating mechanisms within the Vanilloid subfamily. Sequence-based and structure-based alignments have shown conservation within other TRPM family members of key residues mediating TRPM8 sensitivity to cooling agents and antagonists, even though no other TRPM channels have been previously described to be sensitive to cooling agents. We have been particularly interested in TRPM4 because few pharmacological agents are known to modulate the activity of this channel and it is expressed in many tissues, including cardiac, immune, and cancer cells, and mutations have been causally linked to heritable Familial Heart Block. We have explored the sensitivity of TRPM4 to TRPM8 ligands using inside-out patch clamp recordings and found that cooling agents can modulate TRPM4 activity in response to intracellular Ca2+ and that this sensitivity likely arises from the equivalent binding pocket to TRPM8. This structural and functional conservation may facilitate the use of the rich pharmacology of TRPM8 to guide identification or development of TRPM4-specific ligands.

High-throughput investigation of temperature- and ligand-activation of the TRPM8 channel.

The TRPM8 channel functions as the main cold sensor in sensory nerves, where decreases in temperature cause opening of the cation-conducting channel pore. Activation of TRPM8 in neurons is modulated by voltage, lipids, G-proteins, protein kinases, cytosolic calcium and natural compounds such as menthol. These mechanisms tune neural excitability and are likely important for how sensory stimuli are detected, integrated, and perceived as cold, warmth, pain, or analgesia. The molecular mechanisms of activation and regulation of the TRPM8 channel by chemical and physical stimuli are largely unknown, including the mechanism of cold-activation. Here we set out to systematically identify which residues in the transmembrane domain of the TRPM8 channel are determinant for its sensitivity to menthol or cold. We generated a library containing all possible single-residue substitutions and deletions in the transmembrane domain of the channel. This library was benchmarked using patch-clamp electrophysiology and we have developed a high-throughput fluorescence-based assay of ion channel activity. Finally, we will use Sort-seq methods to link genotypes to phenotypes for each of the variants in our libraries. Through this method, it will be possible to link individual residue changes to functional outcomes in TRPM8.

Investigation of factors that influence the temperature sensitivity of the TRPM2 cation channel.

TRPM2 is a cation channel gated by Ca2+, ADPR and PiP2. The channel plays important role in the central and peripheral heat detection. To understand the physiological relevance of the channel in the regulation of body temperature we conducted electrophysiological studies in cell free patches at various temperatures and agonist concentrations. In the temperature range of 15-40°C we found that heating alone cannot open the channel, gating is strictly agonist dependent. Rising temperature increases channel conductance, open probability and apparent agonist binding affinities. We identified a strongly temperature dependent positive feedback on channel activity caused by the Ca2+ influx through the channel's pore. This temperature dependent Ca2+ influx generates a supraphysiological intracellular [Ca2+] nanodomain that tunes channel activity. These findings explain the physiological relevance of the channel in the regulation of body temperature. Based on our measured data we constructed a mechanistic gating model that allows the calculation of agonist concentrations in the channel's direct environment from measured open probabilities at given temperatures. This model allows us to further investigate the TRPM2 channel's temperature dependent function in different cellular environments and study how the resting membrane potential or the intracellular Ca2+ buffering properties modulate the channel's temperature threshold in different cell types.

Exploring the gating mechanisms of the TRPM3 channel.

TRP channels are polymodal sensors that detect a variety of physiological stimuli. TRPM3, a member of the TRP channel family, is a nonselective cation channel implicated in disorders throughout the body, including in diabetes, neurodevelopmental disorders, chronic inflammation, and chronic fatigue syndrome. As such, understanding TRPM3 function and dysfunction could provide valuable insight into physiological functioning and treatment. While TRPM3 has many isoforms, the isoform studied here is the most well-characterized TRPM3 isoform, TRPM3α2. TRPM3α2 is sensitive to heat, depolarizing membrane voltages, and ligands such as pregnenolone sulfate (PS). While PS is not specific for TRPM3, it is currently the most used agonist for the channel as it activates the channel at physiological concentrations and elicits an intracellular signaling cascade typical of TRPM3 stimulation. TRPM3α2 is also interesting from a mechanistic perspective because it has been proposed to have two ion permeation pathways, one at the central axis within the pore domain formed by S5-S6 helices and activated by PS, and a second activated by other agonists and located within S1-S4 domains that resemble voltage-sensing domains in voltage-activated potassium (Kv) channels. We began by identifying ionic conditions where we could measure macroscopic ionic currents during test depolarizations and tail currents upon membrane repolarization. We find that symmetrical CsCl based solutions seem to stabilize the open state of TRPM3, whether examining voltage-dependent activation at room temperature in the absence of other activators, or in the presence of PS, enabling robust resolution of tail current. Using tail current measurements, we observed that the conductance (G) - voltage (V) relationship for TRPM3 is complex, with distinct components at negative and positive membrane voltages. We are currently exploring ligands thought to activate the alternate permeation pathway and using mutagenesis to localize the PS binding site.

A TRPM7 mutation linked to familial trigeminal neuralgia: Omega current and hyperexcitability of trigeminal ganglion neurons.

Trigeminal neuralgia (TN) is a unique pain disorder in which affected individuals experience intense paroxysmal pain in the territory of the trigeminal nerve. Although most cases of TN are sporadic, occurrence of familial TN suggests a genetic contribution to this disorder. Here we used Ca2+ and Na+ imaging and whole-cell patch clamp to assess a variant in the TRPM7 channel kinase, p.Ala931Thr, found in a man suffering from unilateral TN. We found that A931T generated a 20-fold higher inward currents than TRPM7 WT and unchanged outward currents. The inward current recorded in A931T had the following properties: i) it was carried by Na+ ions under physiological conditions; ii) it was insensitive to the pore blocker Gd3+; iii) it was observed when Na+ was replaced by Guanidinium, but it was completely suppressed by application of NMDG+.

Hyperexcitability reduces TRPM5 in pancreatic β-cells: Insights into disruption of insulin secretion in chronically stimulated islets.

Acute inhibition of ATP-sensitive K+ (KATP) channels in pancreatic β-cells results in depolarization, Ca2+ influx, and insulin secretion. Accordingly, loss of KATP is associated with congenital hyperinsulinism in humans. However, many patients with congenital hyperinsulinism caused by KATP LOF mutations gradually remit or even progress to a diabetic state, and adult mice that chronically lack KATP exhibit reduced insulin secretion and are glucose-intolerant. The mechanism for this counterintuitive progression remains unknown. Ca2+ imaging revealed elevated [Ca2+]i at low glucose in islets from KATP KO animals, but mean [Ca2+]i is similar to WT in high glucose. To look for potential contributors to reduced insulin secretion in KATP KO, we examined gene expression using whole islet and single cell RNAseq and qPCR in several different mouse models of loss of β-cell KATP­ activity. One of the most consistent and marked changes is a profound decrease in expression of the [Ca2+]i-activated non-selective cation channel TRPM5 in all models. TRPM5 is normally expressed in β cells and acts to promote insulin secretion. Steviol, a pharmacological activator of TRPM5, increased [Ca2+]i in WT islets at all glucose levels, but there was no response to steviol in KATP KO islets. Furthermore, steviol failed to stimulate insulin secretion in KATP KO animals. The data suggest that loss of TRPM5 may contribute to reduced levels of stimulatory [Ca2+]i and to reduced insulin secretion following KATP loss. These findings represent new insights to a phenomenon that has long remained unexplained, yet is critical to understand, given the potentially profound clinical consequences.

Molecular taxonomy of nociceptors and pruriceptors.

Molecular taxonomy of nociceptors and pruriceptors.

Ion channel thermodynamics studied with temperature jumps measured at the cell membrane

Perturbing the temperature of a system modifies its energy landscape, thus providing a ubiquitous tool to understand biological processes. Here, we developed a framework to generate sudden temperature jumps (Tjumps) and sustained temperature steps (Tsteps) to study the temperature dependence of membrane proteins under voltage clamp while measuring the membrane temperature. Utilizing the melanin under the Xenopus laevis oocytes membrane as a photothermal transducer, we achieved short Tjumps up to 9°C in less than 1.5 ms and constant Tsteps for durations up to 150 ms. We followed the temperature at the membrane with sub-ms time resolution by measuring the time course of membrane capacitance, which is linearly related to temperature. We applied Tjumps in Kir1.1 isoform b, which reveals a highly temperature-sensitive blockage relief, and characterized the effects of Tsteps on the temperature-sensitive channels TRPM8 and TRPV1. These newly developed approaches provide a general tool to study membrane protein thermodynamics.

Calcineurin-Inhibitor-Induced Hypomagnesemia in Kidney Transplant Patients: A Monocentric Comparative Study between Sucrosomial Magnesium and Magnesium Pidolate Supplementation.

Magnesium (Mg) contributes to DNA stability, protein synthesis and cardiac excitability, while Mg deficiency leads to increased cardiovascular mortality, diabetes, hyperparathyroidism and risk of fractures. In kidney transplant patients, calcineurin inhibitors (CNIs) downregulating Mg channel TRPM6 in the distal collecting tubule induce early hypomagnesemia (HypoMg), which is associated with a faster decline in allograft function. A new formulation, sucrosomial Mg (SucrMg), for oral supplements encapsulates Mg oxide in a phospholipid membrane covered by a sucrester matrix, enhancing gastric and intestinal Mg absorption. This study has evaluated Mg bioavailability, effectiveness and tolerance of SucrMg compared to the conventional preparation of Mg pidolate (PidMg). The association of blood Mg with risk of post-transplant dysglycemia and hyperparathyroidism has also been investigated. Forty hypomagnesemic adult single, double or combined kidney-pancreas or kidney-liver transplant recipients within 2 years from transplantation were recruited. In total, 16 patients received PidMg and 27 received SucrMg. Blood Mg was measured at baseline (T0), after 15 days (T1) and after 6 months (T2) of treatment. PTH, fasting glucose and calcium were measured at baseline and after 6 months of treatment. The tolerance was evaluated at the ambulatory visits. SucrMg compared to PidMg was more efficient at increasing Mg bioavailability at T1: p < 0.0001 vs. p = 0.72 ns, respectively, with a ∆% increase of 12.4% vs. 5.4%, p = 0.04. Both preparations increased blood Mg at T2, p < 0.0001 and p = 0.002, respectively. SucrMg was better tolerated. No difference was observed for fasting plasma glucose, PTH and calcium. On one hand, our study is the first among transplant patients to evaluate the efficacy of SucrMg in the correction of HypoMg, which might justify the limited number of patients enrolled and the short observation time; on the other hand, our results could serve as a useful working hypothesis for further studies with a larger number of transplant patients and an extended study duration to confirm the benefits observed with SucrMg.

NMDA Receptor Activation Stimulates Hypoxia-Induced TRPM2 Channel Activation, Mitochondrial Oxidative Stress, and Apoptosis in Neuronal Cell Line: Modular Role of Memantine

TRPM2 channel is activated by the increase of hypoxia (HYP)-mediated excessive mitochondrial (mROS) and cytosolic (cROS) free reactive oxygen species generation and intracellular free Ca2+ ([Ca2+]i) influx. The stimulations of the N-methyl-d-aspartate(NMDA) receptor and TRPM2 channel induce mROS and apoptosis in the neurons, although their inhibitions via the treatments of memantine (MEM) and MK-801 decrease mROS and apoptosis. However, the molecular mechanisms underlying MEM treatment and NMDA inhibition’ neuroprotection via TRPM2 inhibition in the HYP remain elusive. We investigated the modulator role of MEM and NMDA via the modulation of TRPM2 on oxidative neurodegeneration and apoptosis in SH-SY5Y neuronal cells. Six groups were induced in the SH-SY5Y and HEK293 cells as follows: Control, MEM, NMDA blocker (MK-801), HYP (CoCl2), HYP + MEM, and HYP + MK-801. The HYP caused to the increases of TRPM2 and PARP-1 expressions, and TRPM2 agonist (H2O2 and ADP-ribose)-induced TRPM2 current density and [Ca2+]i concentration via the upregulation of mitochondrial membrane potential, cROS, and mROS generations. The alterations were not observed in the absence of TRPM2 in the HEK293 cells. The increase of cROS, mROS, lipid peroxidation, cell death (propidium iodide/Hoechst) rate, apoptosis, caspase −3, caspase −8, and caspase −9 were restored via upregulation of glutathione and glutathione peroxidase by the treatments of TRPM2 antagonists (ACA or 2-APB), MEM, and MK-801. In conclusion, the inhibition of NMDA receptor via MEM treatment modulated HYP-mediated mROS, apoptosis, and TRPM2-induced excessive [Ca2+]i and may provide an avenue for protecting HYP-mediated neurodegenerative diseases associated with the increase of mROS, [Ca2+]i, and apoptosis.

Selection of preferred thermal environment and cold-avoidance responses in rats rely on signals transduced by the dorsal portion of the lateral funiculus of the spinal cord

ABSTRACT Thermoregulatory behaviors are powerful effectors for core body temperature (Tc) regulation. We evaluated the involvement of afferent fibers ascending through the dorsal portion of the lateral funiculus (DLF) of the spinal cord in “spontaneous” thermal preference and thermoregulatory behaviors induced by thermal and pharmacological stimuli in a thermogradient apparatus. In adult Wistar rats, the DLF was surgically severed at the first cervical vertebra bilaterally. The functional effectiveness of funiculotomy was verified by the increased latency of tail-flick responses to noxious cold (−18°C) and heat (50°C). In the thermogradient apparatus, funiculotomized rats showed a higher variability of their preferred ambient temperature(Tpr) and, consequently, increased Tc fluctuations, as compared to sham-operated rats. The cold-avoidance (warmth-seeking) response to moderate cold (whole-body exposure to ~17°C) or epidermal menthol (an agonist of the cold-sensitive TRPM8 channel) was attenuated in funiculotomized rats, as compared to sham-operated rats, and so was the Tc (hyperthermic) response to menthol. In contrast, the warmth-avoidance (cold-seeking) and Tc responses of funiculotomized rats to mild heat (exposure to ~28°C) or intravenous RN-1747 (an agonist of the warmth-sensitive TRPV4; 100 μg/kg) were unaffected. We conclude that DLF-mediated signals contribute to driving spontaneous thermal preference, and that attenuation of these signals is associated with decreased precision of Tc regulation. We further conclude that thermally and pharmacologically induced changes in thermal preference rely on neural, presumably afferent, signals that travel in the spinal cord within the DLF. Signals conveyed by the DLF are important for cold-avoidance behaviors but make little contribution to heat-avoidance responses.