Capsaicin fails to produce changes in contractile tension in large gut of neonate rats

Objectives: Capsaicin, the most pungent constituent of chilli pepper (Capsicum annuum L.), is known to alter the physiological activity of the gut. Capsaicin mediates its action through a transient receptor potential vanilloid type 1 (TRPV1) channel. The action of capsaicin on gut smooth muscle varies from segment to segment in different species. The earlier studies were carried out in adult animals only, and its status in the neonate gut, which is in a development stage, is not known. Objective: Therefore, the present study was done to assess the effect of capsaicin on the large gut of neonates. Materials and Methods: In an organ bath preparation, isometric contractions were recorded from segments of dissected rat colon and rectum. The gut segments were exposed to cumulative concentrations of capsaicin (0.01 nM–3 µM) and a capsaicin-induced contractile response was observed. TRPV1 receptor antagonist capsazepine (1 µM) and a nitric oxide synthase inhibitor, L-NAME (100 µM), were used to assess their blocking effect on capsaicin-induced contractile response. Results: Capsaicin raised contractile tension in the colon and rectum of adult rats but not in neonate rats. In adult rats, capsazepine pre-treatment (1 µM) failed to block the capsaicin-induced response in the colon, but in the lower concentrations, it increased contractile tension in the rectum. Pre-application of L-NAME (100 µM) potentiated capsaicin-induced response in the adult rectum and neonate’s colon but had no effect in the neonate rectum and adult colon. Capsaicin with a low concentration (0.01 nM–0.01 µM) increased contractile frequency in both the colon and rectum of adult rats. However, the effect of capsaicin on frequency was abolished at higher concentrations (0.01 µM–3 µM). A capsaicin-evoked change in contractile frequency in adult rats was blocked by capsazepine and L-NAME. At lower concentrations (0.01 nM–0.01 µM), capsaicin did not show any change in frequency in the neonatal colon, while a decrease in contractile frequency was observed with the higher concentrations (0.1 µM–3 µM) of capsaicin. In neonates, capsazepine pre-treatment produced changes in frequency for both the colon and rectum. However, pre-application of L-NAME decreased frequency in the neonate rectum but not in the colon. Conclusion: Capsaicin-induced changes in contractile activity may or may not involve TRPV1 or the Nitric Oxide (NO) pathway, depending on the part of the large gut and developmental maturity.

‘TRAIL’ of targeted colorectal cancer therapy

TRAIL, a tumor necrosis factor-related apoptosis-inducing ligand is a member of the tumor necrosis factor (TNF) superfamily, which is a cytokine that has shown a particularly precise and selective affinity towards death receptors that are overexpressed in cancer cells. While leaving the normal cells intact and unharmed, due to this property it has been the ligand of choice for highly precise cancer chemotherapeutic delivery system development. On numerous occasions, TRAIL has been used singularly and in combination with other drugs. It was observed that TRAIL had a tendency to be susceptible in terms of the cancer cells developing resistance against it. So TRAIL monotherapy was a bit of a rough patch for the molecule to become successful in the chemotherapy universe, however the conjugations and synergistic actions of TRAIL opened up new horizons which are discussed in this review with specific interest on colorectal cancer (CRC).

Regulation of capsaicin receptor TRPV1 on depressive behavior and neuronal autophagy in cerebral ischemia-reperfusion mice / 中华行为医学与脑科学杂志

Objective:To explore the effect and molecular mechanism of capsaicin receptor(TRPV1) on neuronal autophagy and depression-like behavior in mice.Methods:Using the method of random number table, 87 C57 male mice were divided into Sham operation group (Sham group), cerebral ischemia/reperfusion group (I/R group) and capsazepine(CPZ) preconditioning cerebral ischemia/reperfusion group (I/R+ CPZ group), with 28 mice in each group due to 3 incompatible.Mice in the I/R group were subjected to right middle cerebral artery occlusion (MCAO) to establish a cerebral ischemia-reperfusion model.Mice in the I/R+ CPZ group were injected with CPZ in the lateral ventricle prior to moulding.Mice in the Sham group had only wire plugs inserted and no arterial embolization was performed.The mNSS score was used to evaluate the degree of neurological deficits.The depression-like behaviour of mice was detected by the tail suspension test and forced swimming test.The infarct volume was observed by TTC staining.The pathological changes in the amygdala were observed by HE staining, and the expression of Beclin-1, LC3, p62 and p-PI3K, p-AKT and p-mTOR proteins were detected by Western blot.Statistical analysis was performed using SPSS 23.0 software.The t-test was used for comparison between two groups and one-way ANOVA was used for comparison of multiple group. Results:The neurological deficit score in I/R+ CPZ group (9.77±2.32) was significantly lower than that in I/R group (12.85±2.73) ( t=3.10, P<0.01). Compared with I/R group, the tail suspension immobility time of I/R+ CPZ Group ((93.28±50.69)s, (143.80±35.61) s; t=2.94, P<0.01) and the forced swimming immobility time ((139.50±13.33)s, (175.30±19.78)s; t=2.94, P<0.01) were significantly reduced.The results of TTC staining showed that the cerebral infarct volume in I/R+ CPZ group was significantly lower than that in I/R group ((19.30±5.19)%, (33.60±3.90)%; t=5.40, P<0.01). HE staining showed that the number of cells in the amygdala region of mice in the I/R+ CPZ group increased compared with that in the I/R group, with tighter arrangement and reduced deep staining of nuclear fixation.Western blot showed that compared with I/R group, the expression levels of autophagy related proteins Beclin-1( t=2.94, P<0.05) and LC3 ( t=3.16, P<0.05) in amygdala of I/R+ CPZ group were down-regulated, while the expression levels of p62( t=3.60, P<0.05), p-PI3K ( t=7.79, P<0.01), p-AKT ( t=4.15, P<0.01) and p-mTOR ( t=6.15, P<0.01) were up-regulated. Conclusion:Cerebral ischemia/reperfusion activates neuronal autophagy, and CPZ may regulate the PI3K-AKT-mTOR pathway, thus inhibits excessive activation of autophagy, thereby acting as a neuroprotective agent and improving post-stroke depression-like behaviour.

TRPV1 Blocking Alleviates Airway Inflammation and Remodeling in a Chronic Asthma Murine Model

PURPOSE: Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and remodeling. There is emerging interest in the involvement of the transient receptor potential vanilloid 1 (TRPV1) channel in the pathophysiology of asthma. This study examined whether TRPV1 antagonism alleviates asthma features in a murine model of chronic asthma. METHODS: BALB/c mice were sensitized to and challenged by ovalbumin to develop chronic asthma. Capsazepine (TRPV1 antagonist) or TRPV1 small interfering RNA (siRNA) was administered in the treatment group to evaluate the effect of TPV1 antagonism on AHR, airway inflammation, and remodeling. RESULTS: The mice displayed increased AHR, airway inflammation, and remodeling. Treatment with capsazepine or TRPV1 siRNA reduced AHR to methacholine and airway inflammation. Type 2 T helper (Th2) cytokines (interleukin [IL]-4, IL-5, and IL-13) were reduced and epithelial cell-derived cytokines (thymic stromal lymphopoietin [TSLP], IL-33, and IL-25), which regulate Th2 cytokine-associated inflammation, were also reduced. Airway remodeling characterized by goblet cell hyperplasia, increased α-smooth muscle action, and collagen deposition was also alleviated by both treatments. CONCLUSIONS: Treatment directed at TRPV1 significantly alleviated AHR, airway inflammation, and remodeling in a chronic asthma murine model. The TRPV1 receptor can be a potential drug target for chronic bronchial asthma.

Targeting calcium signaling in cancer therapy

The intracellular calcium ions (Ca) act as second messenger to regulate gene transcription, cell proliferation, migration and death. Accumulating evidences have demonstrated that intracellular Cahomeostasis is altered in cancer cells and the alteration is involved in tumor initiation, angiogenesis, progression and metastasis. Targeting derailed Casignaling for cancer therapy has become an emerging research area. This review summarizes some important Cachannels, transporters and Ca-ATPases, which have been reported to be altered in human cancer patients. It discusses the current research effort toward evaluation of the blockers, inhibitors or regulators for Cachannels/transporters or Ca-ATPase pumps as anti-cancer drugs. This review is also aimed to stimulate interest in, and support for research into the understanding of cellular mechanisms underlying the regulation of Casignaling in different cancer cells, and to search for novel therapies to cure these malignancies by targeting Cachannels or transporters.

Capsazepine in rats′lateral ventricles:Effect of different doses on LPS-induced fever / 中国药理学通报

Aim To observe the effects of the transient receptor potential vanilloid receptor 1 ( TRPV1 ) antago-nist Capsazepine on the LPS-induced fever process. Methods Three doses of Capsazepine were respec-tively injected into rats’ lateral ventricles before the in-traperitoneal injection of LPS caused fever. An emitter was implanted inside the rat’ s abdominal cavity to mo-nitor the body temperature changes during the fever process. Then the changes of calcium ion in the hypo-thalamus were detected by fluorescence and the expres-sions of TRPV1 protein were detected by Western blot. Results The higher dosage of Capsazepine was injec-ted, the higher the level of LPS-induced fever was, and the lower the concentration of calcium ion in the hypothalamus as well as the TRPV1 expressions were. Conclusion Capsazepine could increase the level of fever induced by LPS via acting on the rats’ hypothala-mus. This effect might be related to the functions of TRPV1 .

High dose of QX-314 produces anti-nociceptive effect without capsaicin in rats with inflammatory TMJ pain

The present study investigated the effects of QX-314 on inflammatory pain of the temporomandibular joint (TMJ). Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Under anesthesia, the TMJ of each animal was injected with 50 microL of formalin (5%). The number of noxious behavioral responses, including rubbing or scratching of the facial region including the TMJ area, was recorded over 9 sequential 5 min intervals for each animal. Although 2.5% QX-314 did not affect formalin-induced nociceptive behavior, administration of 5% QX-314 with formalin significantly decreased the number of scratches produced by the formalin injection. Co-administration of capsaicin, a TRPV1 agonist, with 2.5% QX-314 produced significant anti-nociceptive effects whereas 2.5% QX-314 alone did not. However, the co-administration of capsaicin did not enhance the anti-nociceptive effects in the 5% QX-314-treated rats. Moreover, the co-administration of capsazepine, a TRPV1 antagonist, did not attenuate anti-nociceptive effects in the 5% QX-314-treated rats. These findings suggest that TRPV1 is effective in the transport of low but not high doses of QX-314. Moreover, a high dose of QX-314, which is not mediated by peripheral TRPV1 activity, may be viable therapeutic strategy for inflammatory pain in the TMJ.

Rat Trigeminal Ganglion Neuron Responses to Piperine in a Low-pH Environment, and Capsazepine-Induced Block

This study examined the responses of cultured adult rat trigeminal ganglion neurons to protons and to capsazepine and piperine, two substances known to produce pain and hyperalgesia in humans. Whole-cell patch clamp recordings were performed on cultured adult rat trigeminal ganglion(TG) neurons voltage-clamped near their resting membrane potential(-60mV). Piperine(10nM) caused a sustained inward current associated with either an increase or decrease in membrane conductance. When protons and piperine were coapplied, the membrane currents evoked in piperine-sensitive TG neurons far exceeded the algebraic sum of the responses to the two stimuli applied in isolation. Capsazepine blocked the response of TG neurons to piperine at both physiological and acidic pH. In the presence of capsazepine, responses to the mixture of piperine and protons resembled the response to a low pH stimulus applied alone. Capsazepine had no effect on sustained proton-induced current. These findings suggest that protons enhance piperine current by altering the vanilloid receptor/channel complex or by increasing the length constant of the space clamp. This study reveals that cultured trigeminal ganglion neurons show features of chemonociceptors and may provide a useful model for studying the mechanism of chemical pain production.

Effects of TRPV1 on LPS-induced fever and the content of Ca~(2+) and cAMP in hypothalamus in rats / 中国药理学通报

group N;?T(300～480 min) and TRI8 of group CPZ+LPS was significantly higher than that of group LPS(P