Neuroscience

TRPV3 channel activity helps cortical neurons stay active during fever

Yiming Shen
Richárd Fiáth
István Ulbert
Michelle W Antoine author has email address

Section on Neural Circuits, National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
Center of Neurosurgery and Neurointervention, Semmelweis University, Budapest, Hungary

https://doi.org/10.7554/eLife.102412.1

Open access
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Figures and data

Body Temperature rises to fever levels during regular activity and exposure to higher ambient temperatures.
A. Left: Setup for recording mouse body temperature( (T_b) at room temperature using an implanted transponder for non-invasive measurement. Right: Average T_b readings over 6 hours at 5-minute intervals for 10 mice. T_b typically hovers around 37°C during the day.
B. T_b may briefly elevate into fever range (shaded red bars) during regular daily activity. Median with upper and lower limits indicated.
C. T_b readings over 6 hours, at 5-minute intervals for animal 3 in Figure 1B. Shaded red dots indicate time points when T_b enters the fever range.
D. Left: Setup for T_b recordings during infrared light exposure. Right: T_b elevates into the fever range ( >38°C) for extended durations, lasting minutes to hours. Average T_b readings over 6 hours at 5-minute intervals for 10 mice.

Spiking in P12-14 cortical excitatory pyramidal neurons remains stable as temperature enters the fever range.
A. Setup for recording L4-evoked postsynaptic potential and spiking in an excitatory pyramidal neuron (PN) at just-subthreshold V_m at 30°C, 36°C and 39°C in mouse primary somatosensory (S1) cortex.
B. Example traces of L4-evoked spikes in L2/3 PN during consecutive recordings at 30°C (black), 36°C (gray), and 39°C (red).
C. Depolarization required to reach spike threshold (ST) in L2/3 PNs during temperature elevations from 30°C to 39°C.
D. Same as (C) for input resistance (R_in).
E. Same as (C) for the percentage of spiking L2/3 PNs.
F. Same as in (C) for the spiking distribution.
G. Same as in (C) for the number of spikes.
Each data point represents an individual cell. 37 PNs recorded from 14 animals. Mean with standard error of the mean shown in C, D and G. Statistical significance assessed via one-way repeated measures ANOVA with Tukey’s test at α=0.05.

Spiking in P7-8 cortical excitatory pyramidal neurons decreases as temperature enters the fever range.
A. Setup for recording L4-evoked postsynaptic potential and spiking in an excitatory pyramidal neuron (PN) at just-subthreshold V_m at 30°C, 36°C and 39°C in mouse primary somatosensory (S1) cortex.
B. Example traces of L4-evoked spikes in L2/3 PN during consecutive recordings at 30°C (black), 36°C (gray), and 39°C (red).
C. Depolarization required to reach spike threshold (ST) in L2/3 PNs during temperature elevations from 30°C to 39°C.
D. Same as (C) for input resistance (R_in).
E. Same as (C) for the percentage of spiking L2/3 PNs.
F. Same as in (C) for the spiking distribution.
G. Same as in (C) for the number of spikes.
Each data point represents an individual cell. 19 PNs recorded from 5 animals. Mean with standard error of the mean shown in C, D and G. Statistical significance assessed via one-way repeated measures ANOVA with Tukey’s test at α=0.05.

Increased depolarization at higher spike thresholds helps maintain stable spiking activity in cortical pyramidal neurons during temperature elevations.
A. Illustration demonstrating how temperature-induced changes in spike threshold make spiking more challenging for a neuron, requiring larger levels of depolarization to sustain spiking.
B. Example traces of L4-evoked postsynaptic potentials (PSPs) in L2/3 PN during consecutive recordings at 30°C (black), 36°C (gray), and 39°C (red).
C. Correlation of PSP peak versus spike threshold (ST). r = Pearson correlation coefficient with Deming linear regression.
D. Correlation of input resistance versus ST. r = Pearson correlation coefficient with simple linear regression.
E. Same as D but for input resistance versus PSP.
F. Illustration showing how temperature-induced loss in inhibition (blue IPSP) could lead to larger levels of depolarization. IPSPs typically bring the membrane potential away from the spike threshold.
G. The late PSP peak in L2/3 PNs during temperature elevations from 30°C to 39°C. Statistical significance was evaluated on log-transformed data using one-way repeated measures ANOVA with Tukey’s test, with significance at α=0.05.
H. Same as D but for PSP versus Late PSP Peak.
r = Spearman correlation coefficient with simple linear regression.

Cortical neurons that remain active at febrile temperatures spike at higher rates, but the excitatory-inhibitory balance remains unchanged.
A. Setup for in vivo recording of spiking in mouse S1 cortex during temperature increases from 36°C to 39°C and cooling back to 36°C.
B. Normalized firing rates from putative excitatory PNs and interneurons obtained from recordings in A.
C. Left: Setup for ex vivo recording of L4-evoked postsynaptic potential and spiking in a L2/3 PN at just-subthreshold V_m at 30°C, 36°C and 39°C in mouse S1 cortex. Right: Percent distribution for recorded PNs that never spiked, stopped spiking, stayed spiking, or started spiking during temperature increases from 36°C to 39°C.
D. L2/3 PN spiking activity in neurons that stayed spiking (left), started spiking (middle), and stopped spiking (right) upon temperature increases from 36°C to 39°C.
E. Left: Setup for ex vivo recording of L4-evoked excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs, respectively). Right: The excitatory-inhibitory (E-I) balance (defined as E/E+I, the ratio of the EPSC to the total current (EPSC+IPSC) measurements during temperature increases from 36 to 39°C.
F. Activity distribution for ex vivo recorded neurons that never spiked, and those that stopped spiking, stayed spiking, or started spiking upon temperature increases from 36°C to 39°C. P-value = 0.01 indicates a significant increase in the fraction of neurons that stayed spiking during temperature increases from 36°C to 39°C (solid red bar).
In B,D and E, each data point represents an individual cell. Data collected from 5 animals (in B), 11 animals (in C,D), 7 animals (in E) and 9-14 animals (in F). Mean with standard error mean is indicated in B and E. Significance assessed by paired two-tailed t-test (D and E), one- way repeated measures ANOVA with Tukey’s test (in B) and binomial test (in F). Significance at α=0.05.

Excitatory pyramidal neurons that remain spiking with temperature elevations into fever range exhibit unique intrinsic properties.
Neurons that spiked at all temperatures (30°C, 36°C, and 39°C) are STAY PNs, while those that stopped spiking at 36°C or 39°C are STOP neurons.
A. Depolarization required to reach spike threshold (ST) in STOP and STAY L2/3 PNs during temperature elevations from 30°C to 39°C.
B. Same as (A) for L4-evoked postsynaptic potentials (PSPs)
C. Correlation of PSP peak versus ST in STAY L2/3 PNs at 30°C, 36°C, and 39°C. r = Pearson correlation coefficient with Deming linear regression.
D. Same as (C) for STOP cells.
E. Same as (A) for the L4-evoked late PSP peak.
F. Same as (A) for spike height.
G. Same as (A) for spike afterhyperpolarization (AHP).
H. Same as (A) for input resistance.
Each data point represents an individual cell in A-H. Data collected from 14 animals. Mean with standard error mean is indicated in A-B and E-H. Significance assessed by one- and two-way repeated measures ANOVA with Tukey’s or Sidak post-hoc test, or paired t-test at α=0.05.

Medium spiny neurons (MSNs) that remain spiking with temperature elevations into fever range exhibit unique intrinsic properties.
Neurons that spiked at all temperatures (30°C, 36°C, and 39°C) are STAY MSNs, while those that stopped spiking at 36°C or 39°C are STOP MSNs.
A. Setup for recording evoked spiking in MSNs expressing dopamine (D)1-type receptors (i.e. D1⁺ MSNs) or D2-type receptors (i.e. D2⁺ MSNs).
B. Example traces of evoked spikes in D1⁺ MSN during consecutive recordings at 30°C (black), 36°C (gray), and 39°C (red).
C. Depolarization required to reach spike threshold (ST) in STOP and STAY D1⁺ MSNs during temperature elevations from 30°C to 39°C.
D. Summed trace (B) for evoked postsynaptic potentials (PSPs).
E. Same as (C) for input resistance.
F. Same as (B) for evoked spikes in D2⁺ MSNs.
G. Same as (C) for ST in D2⁺ MSNs.
H. Same as (B) for evoked PSPs in D2⁺ MSNs.
I. Same as (C) for input resistance in D2⁺ MSNs
Each data point represents an individual cell in C-D and G and I. Summed trace from all recordings is indicated in D and H. Data collected from 6 animals in C-E and 4 animals in F-G . Mean with standard error mean is indicated in C-D and F-G. Significance assessed by one- and two-way repeated measures ANOVA with Tukey’s or Sidak post-hoc test, or paired t-test at α=0.05.

Temperature elevations in fever range increase TRPV3 currents in cortical pyramidal neurons.
A. Setup for recording whole-cell TRPV3 currents at 30°C (black), 36 °C (grey) and 39°C (red). in cortical excitatory pyramidal neurons (PNs) with bath application of camphor (5mM), a TPRV3 agonist.
B. Current density-voltage (I-V) relationship of TRPV3 currents at 30°C (black), 36 °C (grey) and 39°C (red) in WT mice: 11 cells from 4 mice.
C. Scatter dot plots of the current density-voltage measurements.
D. Current density-voltage (I-V) relationship of TRPV3 currents at 30°C (black) in the presence of camphor (5mM), a TPRV3 agonist, or camphor (5mM) + TRPV3 blocker (Forsythoside B, 50 µM) (blue).
E. Same as (D) but for 36°C.
F. Same as (D) but for 39°C.
G. Current density-voltage (I-V) plot showing the net TRPV3 current ( opener – ( opener+ blocker) condition).

Inhibiting TRPV3, but not TRPV4 channels, significantly reduced the population of STAY pyramidal neurons and spiking levels at fever temperature.
A. Setup for recording L4-evoked postsynaptic potential and spiking in an excitatory pyramidal neuron (PN) with an intracellular blocker of TRPV3 channels (Forsythoside B, 50 µM) (left) or TRPV4 channels (RN1734, 10 µM) (right) at just-subthreshold V_m at 30°C, 36°C, and 39°C in mouse S1 cortex.
B. Percentages of cell types obtained from experiment in A.
C. Evoked spikes in L2/3 PNs during temperature elevations to 30°C, 36°C, and 39°C with TRPV3 (Forsythoside B, 50 µM) or TRPV4 (RN1734, 10 µM) blockers.
D. Correlation of PSP peak versus spike threshold (ST). r = Pearson correlation coefficient with Deming linear regression.
E. Same as (C) for the L4-evoked late PSP peak.
F. Same as (C) for input resistance.
Each data point represents an individual cell in C, E and F. Data collected from 26 cells in 7 animals for TRPV3 blocker, 24 cells in 6 animals for TRPV4 blocker, and 37 cells from 14 animals for no block condition. Mean with standard error mean is indicated in C, E and F. Significance assessed by one- and two-way repeated measures ANOVA with Tukey’s or Sidak post-hoc test at α=0.05.

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