Clustering and Differentiation of glr-3 Gene Function and Its Homologous Proteins

In order to adapt to the low temperature environment, organisms transmitexcitement to the central system through the thermal sensing system, whichis a classic reflex reaction. The cold receptor GLR-3 perceives cold and produces cold avoidance behavior through peripheral sensory neurons ASER.In order to further understand the gene encoding of the cold sensing glr-3gene and the evolution of its homologous gene group function and proteinfunction, the nucleotide sequence and amino acid sequence of the glr-3gene and its homologous gene in 24 species were obtained and compared.By clustering with the GRIK2 gene sequence of Rana chensinensis, the bioinformatics method was used to predict and sequence analyze the change ofgene, evolution rate, physical and chemical properties of protein, glycosylation sites, phosphorylation sites, secondary structure and tertiary structureof protein. The analysis results show that the glr-3 gene and its homologousgene have obvious positive selection effect. The protein prediction analysisshowed that the glr-3 gene and its homologous genes encoded proteinsin these 25 species were hydrophilic proteins, and the proportion of sidechains of aliphatic amino acids was high. The transmembrane helix waswidespread and there were more N-glycosylation sites and O-glycosylationsites. The protein phosphorylation sites encoded were serine, threonine andtyrosine phosphorylation sites. Secondary structure prediction showed thatthe secondary structure units of the encoded protein were α-helix, β-turn,random coil and extended chain, and the proportion of α-helix was the largest. This study provides useful information on the evolution and function ofthe cold sensing gene glr-3 and its homologous genes.

The Effect and Possible Mechanism of Intradiscal Injection of Simvastatin in the Treatment of Discogenic Pain in Rats

To study the effect of intradiscal injection of simvastatin on discogenic pain in rats and its possible mechanism, 30 adult female rats were used in this experiment. Twenty rats were randomly divided into sham operation group (Control group), intervertebral disk degeneration group (DDD group), intervertebral disk degeneration + hydrogel group (DDD + GEL group), and intervertebral disk degeneration + simvastatin group (DDD + SIM group). The mechanical pain threshold and cold sensation in rats were measured. The contents of NF-kappa B1, RelA, GAP43, SP, CGRP, TRPM 8, IL-1β, and TNF-α in the intervertebral disk (IVD), the corresponding contents of dorsal root ganglion (DRG) and plantar skin GAP43 and TRPM 8 were quantitatively detected by PCR. The corresponding IVDs were stained to detect their degeneration. There was no significant difference in the mechanical pain threshold between the groups at each time point. From the first day to the 8th week after surgery, the cold-sensing response of the DDD group was significantly higher than that of the Control group (P < 0.05). At 7 and 8 weeks postoperatively, the cold-sensing response of the DDD + SIM group was significantly lower than that of the DDD + GEL group (P < 0.05). The levels of NF-κB1, RelA, GAP43, SP, CGRP, TRPM8, IL-1β, and TNF-α in the IVD of DDD + SIM group were significantly lower than those in DDD group (P < 0.05). The content of GAP43 and TRPM8 in rat plantar skin decreased significantly and TRPM8 in DRG decreased significantly (P < 0.05).

Odontoblast TRPC5 channels signal cold pain in teeth

Teeth are composed of many tissues, covered by an inflexible and obdurate enamel. Unlike most other tissues, teeth become extremely cold sensitive when inflamed. The mechanisms of this cold sensation are not understood. Here, we clarify the molecular and cellular components of the dental cold sensing system and show that sensory transduction of cold stimuli in teeth requires odontoblasts. TRPC5 is a cold sensor in healthy teeth and, with TRPA1, is sufficient for cold sensing. The odontoblast appears as the direct site of TRPC5 cold transduction and provides a mechanism for prolonged cold sensing via TRPC5’s relative sensitivity to intracellular calcium and lack of desensitization. Our data provide concrete functional evidence that equipping odontoblasts with the cold-sensor TRPC5 expands traditional odontoblast functions and renders it a previously unknown integral cellular component of the dental cold sensing system.

The evolution of cold nociception in drosophilid larvae and identification of a neural basis for cold acclimation

Cold temperatures can be fatal to insects, but many species have evolved the ability to cold acclimate, thereby increasing their cold tolerance. While there is a growing body of knowledge concerning the mechanisms underlying cold tolerance, relatively little is known concerning how insects sense noxious cold (cold nociception), or how cold nociception might function in cold tolerance. It has been previously shown that Drosophila melanogaster larvae perform highly stereotyped, cold-evoked behaviors under the control of noxious cold-sensing neurons (nociceptors) innervating the barrier epidermis. In the present study, we first sought to describe cold-nociceptive behavior among 11 drosophilid species with differing cold tolerances and from differing climates. Behavioral analyses revealed that the predominant cold-evoked response among drosophilid larvae is a head-to-tail contraction (CT) behavior, which is likely inherited from a common ancestor. However, despite lack of phylogenetic signal (suggesting trait lability), the CT behavior was transient and there was no clear evidence that cold sensitivity was related to thermal environment; collectively this suggests that the behavior might not be adaptive. We therefore sought to uncover an alternative way that cold nociception might be protective. Using a combination of cold-shock assays, optogenetics, electrophysiology, and methods to genetically disrupt neural transmission, we demonstrate that cold sensing neurons in Drosophila melanogaster (Class III nociceptors) are sensitized by and critical to cold acclimation. Moreover, we demonstrate that cold acclimation can be optogenetically-evoked, sans cold. Collectively, these findings reveal that cold nociception constitutes a peripheral neural basis for Drosophila larval cold acclimation.Significance StatementMany insects adapt to cold in response to developmental exposure to cool temperatures. While there is a growing body of knowledge concerning the mechanisms underlying cold tolerance, it is unknown how sensory neurons might contribute. Here, we show that noxious cold sensing (cold nociception) is widely present among drosophilid larvae, and that cold-sensing neurons (Class III cold nociceptors) are necessary and sufficient drivers of cold acclimation. This suggests that cold acclimation has, at least in part, a neural basis.