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The development of molecular imaging probes to identify key cellular changes within lung metastases may lead to noninvasive detection of metastatic lesions in the lung. In this study, we constructed a macrophage-targeted clickable albumin nanoplatform (CAN) decorated with mannose as the targeting ligand using a click reaction to maintain the intrinsic properties of albumin

Methyl-β-cyclodextrin (MβCD) is a reagent that depletes cholesterol and disrupts lipid rafts, a type of cholesterol-enriched cell membrane microdomain. Lipid rafts are essential for neuronal functions such as synaptic transmission and plasticity, which are sensitive to even low doses of MβCD. However, how MβCD changes synaptic function, such as N-methyl-d-aspartate receptor (NMDA-R) activity, remains unclear. We monitored changes in synaptic transmission and plasticity after disrupting lipid rafts with MβCD. At low concentrations (0.5 mg/mL), MβCD decreased basal synaptic transmission and miniature excitatory post-synaptic current without changing NMDA-R-mediated synaptic transmission and the paired-pulse facilitation ratio. Interestingly, low doses of MβCD failed to deplete cholesterol or affect α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) and NMDA-R levels, while clearly reducing GluA1 levels selectively in the synaptosomal fraction. Low doses of MβCD decreased the inhibitory effects of NASPM, an inhibitor for GluA2-lacking AMPA-R. MβCD successfully decreased NMDA-R-mediated long-term potentiation but did not affect the formation of either NMDA-R-mediated or group I metabotropic glutamate receptor-dependent long-term depression. MβCD inhibited de-depression without affecting de-potentiation. These results suggest that MβCD regulates GluA1-dependent synaptic potentiation but not synaptic depression in a cholesterol-independent manner.

Purinergic signaling participates in skin physiology and pathology, such as hair growth, wound healing, inflammation, pain, and skin cancer. However, few studies have investigated the involvement of purinergic signaling in skin pigmentation. This study demonstrated that extracellular adenosine 5'-triphosphate (ATP) released from keratinocytes by UVB radiation promotes melanin production in primary human epidermal melanocytes and ex vivo skin cultures. Intracellular calcium ion and protein kinase C/CREB signaling contributed to ATP-mediated melanogenesis. Also, P2X7 receptor was proven to play a pivotal role in ATP-mediated melanogenesis because P2X7 receptor blockade abrogated ATP-induced melanin production. In addition, MNT1 cells with P2X7 receptor knockout using CRISPR/Cas9 system did not show any increase in MITF expression when co-cultured with UV-irradiated keratinocytes compared to MNT1 cells with intact P2X7 receptor, which showed increased expression of MITF. In conclusion, our results indicate that the extracellular ATP-P2X7 signaling axis is an adjunctive mechanism in UV-induced melanogenesis. Furthermore, ATP-induced purinergic signaling in melanocytes may alter skin pigmentation.

We recently demonstrated that pain-sensing neurons in the trigeminal system can be selectively anesthetized by co-application of QX-314 with the TRPV1 receptor agonist, capsaicin (QX cocktail). Here we examined whether this new anesthetic strategy can block the neuronal changes in the brainstem following molar tooth extraction in the rat. Adult male Sprague-Dawley rats received infiltration injection of anesthetic 10 min prior to lower molar tooth extraction. Neuronal activation was determined by immunohistochemistry for the proto-oncogene protein c-Fos in transverse sections of the trigeminal subnucleus caudalis (Sp5C). After tooth extraction, c-Fos-like immunoreactivity (Fos-LI) detected in the dorsomedial region of bilateral Sp5C was highest at 2 hrs ( p < .01 vs. naïve ipsilateral) and declined to pre-injury levels by 8 hrs. Pre-administration of the QX cocktail significantly reduced to sham levels Fos-LI examined 2 hrs after tooth extraction; reduced Fos-LI was also observed with the conventional local anesthetic lidocaine. Pulpal anesthesia by infiltration injection was confirmed by inhibition of the jaw-opening reflex in response to electrical tooth pulp stimulation. Our results suggest that the QX cocktail anesthetic is effective in reducing neuronal activation following tooth extraction. Thus, a selective pain fiber ‘nociceptive anesthetic’ strategy may provide an effective local anesthetic option for dental patients in the clinic.

Due, in part, to the unique structure of the tooth, dental pain is initiated via distinct mechanisms. Here we review recent advances in our understanding of inflammatory tooth pain and discuss 3 hypotheses proposed to explain dentinal hypersensitivity: The first hypothesis, supported by functional expression of temperature-sensitive transient receptor potential channels, emphasizes the direct transduction of noxious temperatures by dental primary afferent neurons. The second hypothesis, known as hydrodynamic theory, attributes dental pain to fluid movement within dentinal tubules, and we discuss several candidate cellular mechanical transducers for the detection of fluid movement. The third hypothesis focuses on the potential sensory function of odontoblasts in the detection of thermal or mechanical stimuli, and we discuss the accumulating evidence that supports their excitability. We also briefly update on a novel strategy for local nociceptive anesthesia via nociceptive transducer molecules in dental primary afferents with the potential to specifically silence pain fibers during dental treatment. Further understanding of the molecular mechanisms of dental pain would greatly enhance the development of therapeutics that target dental pain.

In this study, we determined mode of action of a novel carbamoyloxy arylalkanoyl arylpiperazine compound (SKL-NP) on hyperpolarization-activated cyclic nucleotide-gated (HCN) channel currents (Ih) that plays important roles in neuropathic pain. In small or medium-sized dorsal root ganglion (DRG) neurons (< 40 μm in diameter) exhibiting tonic firing and prominent Ih, SKL-NP inhibited Ih and spike firings in a concentration dependent manner (IC50=7.85 μM). SKL-NP-induced inhibition of Ih was blocked by pretreatment of pertussis toxin (PTX) and N-ethylmaleimide (NEM) as well as 8-Br-cAMP, a membrane permeable cAMP analogue. These results suggest that SKL-NP modulates Ih in indirect manner by the activation of a Gi-protein coupled receptor that decreases intracellular cAMP concen- tration. Taken together, SKL-NP has the inhibitory effect on HCN channel currents (Ih) in DRG neurons of rats.

Background Nociceptive-selective local anesthesia is produced by entry of the permanently charged lidocaine-derivative QX-314 into nociceptors when coadministered with capsaicin, a transient receptor potential vanilloid 1 (TRPV1) channel agonist. However, the pain evoked by capsaicin before establishment of the QX-314-mediated block would limit clinical utility. Because TRPV1 channels are also activated by lidocaine, the authors tested whether lidocaine can substitute for capsaicin to introduce QX-314 into nociceptors through TRPV1 channels and produce selective analgesia. Methods Lidocaine (0.5% [17.5 mM], 1% [35 mM], and 2% [70 mM]) alone, QX-314 (0.2% [5.8 mM]) alone, and a combination of the two were injected subcutaneously and adjacent to the sciatic nerve in rats and mice. Mechanical and thermal responsiveness were measured, as was motor block. Results Coapplication of 0.2% QX-314 with lidocaine prolonged the nociceptive block relative to lidocaine alone, an effect attenuated in TRPV1 knockout mice. The 0.2% QX-314 alone had no effect when injected intraplantary or perineurally, and it produced only weak short-lasting inhibition of the cutaneous trunci muscle reflex. Perisciatic nerve injection of lidocaine with QX-314 produced a differential nociceptive block much longer than the transient motor block, lasting 2 h (for 1% lidocaine) to 9 h (2% lidocaine). Triple application of lidocaine, QX-314, and capsaicin further increased the duration of the differential block. Conclusions Coapplication of lidocaine and its quaternary derivative QX-314 produces a long-lasting, predominantly nociceptor-selective block, likely by facilitating QX-314 entry through TRPV1 channels. Delivery of QX-314 into nociceptors by using lidocaine instead of capsaicin produces sustained regional analgesia without nocifensive behavior.

Selective blockade of nociceptive neurons can be achieved by the delivery of permanently charged sodium channel blockers through the pores of nociceptive ion channels. To assess the feasibility of this application in the dental area, we investigated the electrophysiological and neurochemical characteristics of nociceptive dental primary afferent (DPA) neurons. DPA neurons were identified within trigeminal ganglia labeling with a retrograde fluorescent dye applied to the upper molars of adult rats. Electrophysiological studies revealed that the majority of dental primary afferent neurons showed characteristics of nociceptive neurons, such as sensitivity to capsaicin and the presence of a hump in action potential. Immunohistochemical analysis revealed a large proportion of DPA neurons to be IB4-positive and to express TRPV1 and P2X3. Single-cell RT-PCR revealed mRNA expression of various nociceptive channels, including the temperature-sensitive TRPV1, TRPA1, TRPM8 channels, the extracellular ATP receptor channels P2X2 and P2X3, as well as the nociceptor-specific sodium channel, NaV1.8. In conclusion, DPA neurons have the electrophysiological characteristics of nociceptors and express several nociceptor-specific ion channels. Analysis of these data may assist in the search for a new route of entry for the delivery of membrane-impermeant local anesthetics. Abbreviations: AP, action potential; DiI, 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate; DPA, dental primary afferent; FITC, fluorescein 5(6)-isothiocyanate; IB4, isolectin-B4; RT-PCR, reverse-transcription polymerase chain-reaction; TRP, transient receptor potential.