Animals ; Botulinum Toxins, Type A ; pharmacology ; Capsaicin ; pharmacology ; Carbachol ; pharmacology ; Humans ; Keratoconjunctivitis ; surgery ; Phenylephrine ; pharmacology ; Saliva ; drug effects ; Submandibular Gland ; drug effects ; transplantation ; Translational Medical Research

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is the main component in hot peppers, including red chili peppers, jalapenos, and habanero, belonging to the genus Capsicum. Capsaicin is a potent antioxidant that interferes with free radical activities. In the present study, the possible protective effect of capsaicin was studied against methyl methanesulphonate (MMS) induced toxicity in third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg. The third instar was allowed to feed on the diet having different doses of capsaicin and MMS separately and in combination. The results suggested that the exposure of third instar larvae to the diet having MMS alone showed significant hsp70 expression as well as tissue DNA and oxidative damage, whereas the larvae feed on the diet having MMS and capsaicin showed a decrease in the toxic effects for 48-h of exposure. In conclusion, capsaicin showed a dose-dependent decrease in the toxic effects induced by MMS in the third instar larvae of transgenic Drosophila melanogaster.
Acetylcholinesterase ; metabolism ; Animals ; Animals, Genetically Modified ; Anticarcinogenic Agents ; pharmacology ; Capsaicin ; pharmacology ; DNA Damage ; drug effects ; Drosophila melanogaster ; drug effects ; Larva ; drug effects ; Methyl Methanesulfonate ; antagonists & inhibitors

The effects of capsaicin (CAP) on the carotid sinus baroreflex were studied in 30 anaesthetized rats with perfused isolated carotid sinus. The results are as follows. (1) By perfusing the isolated carotid sinus with CAP (1 micromol/L), the functional curve of the baroreflex was shifted to the left and downward, with a peak slope (PS) increasing from 0.34+/-0.01 to 0.42+/-0.01 (P<0.01), whereas the reflex decrease (RD) in mean arterial pressure was enhanced from 36.51+/-1.26 to 45.01+/-0.71 mmHg (P<0.01). Meanwhile, the threshold pressure, equilibrium pressure and saturation pressure were all significantly decreased from 70.43 +/-2.09 to 52.86 +/-2.80 mmHg (P<0.01), 95.5+/-1.71 to 87.00+/-1.58 mmHg (P<0.01) and 177.60+/-1.37 to 163.55+/-2.12 mmHg (P<0.01), respectively. Among the functional parameters of carotid baroreflex, the changes in PS and RD induced by capsaicin were dose-dependent. (2) By pretreatment with ruthenium red (RR, 100 micromol/L), an antagonist of vanilloid receptor subtype 1 (VR(1)), the above effects of CAP on carotid baroreflex were abolished. (3) The CAP-induced change in the baroreflex was also eliminated by pretreatment with glibenclamide (20 microm ol/L), a K(ATP) channel blocker. On the basis of the results, it is concluded that CAP facilitates the carotid baroreflex, an effect of which may be resulted from the opening of K(ATP) channels mediated by VR(1).
Animals ; Baroreflex ; drug effects ; Blood Pressure ; drug effects ; Capsaicin ; pharmacology ; Carotid Sinus ; drug effects ; physiology ; Glyburide ; pharmacology ; In Vitro Techniques ; Male ; Potassium Channel Blockers ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Drug ; antagonists & inhibitors ; Ruthenium Red ; pharmacology ; TRPV Cation Channels

The formalin test is a commonly used animal model of acute and tonic pain. However, the molecular targets of formaldehyde (FA, the main ingredient of the formalin solution) on primary nociceptor cells remain controversial. In this report, the effects of FA on electrophysiologically-identified primary nociceptor cells were evaluated in vitro and the roles of the vanilloid receptor TRPV1 in FA-produced activation of primary nociceptors were also examined at both cellular and behavioral levels. Of 92 acutely dissociated dorsal root ganglion (DRG) cells recorded by current patch-clamp technique, 34% were discharged by FA application with the mean onset latencies of the first action potential (AP) being (367.34+/-32.96) s. All the FA-sensitive cells were identified as nociceptor cells by their distinguishable features of AP including longer duration, existence of a hump (a shoulder or inflection) on the repolarizing phase, and longer after-hyperpolarization of APs. Co-application of capsazepine (CPZ), a competitive antagonist of TRPV1 receptors, could block FA-evoked firing with partial inhibition on the membrane depolarization of all cells tested. Of another 160 cells examined by confocal calcium imaging, 32% were shown to respond to FA with an intracellular Ca(2+) rise. Of 51 FA-sensitive cells, 67% were suppressed by CPZ, suggesting partial involvement of TRPV1 in mediation of the FA-evoked intracellular Ca(2+) rise. Under voltage-clamp mode, 41% of DRG cells were evoked to give rise to inward current with the remaining 59% being unchanged. In separate experiments on the other 56 FA-sensitive cells, concentration-dependent increase in the FA-evoked current amplitude was demonstrated. In comparison with controls, the FA-evoked inward current could be significantly suppressed by CPZ that was further enhanced by HC-030031, a TRPA1 selective antagonist. Finally, local effects of CPZ were confirmed in the formalin test and it was shown that the formalin-induced paw flinches were strongly suppressed by CPZ in phase 1 but with phase 2 being significantly suppressed only during 25-55 min. It is therefore concluded that FA can directly activate a subpopulation of primary nociceptor cells and the FA-induced AP discharges are likely to contribute mainly to phase 1, but not phase 2 of the formalin-induced nociception. The activation of primary nociceptor cells by FA is likely to be mediated, at least in part, through TRPV1 and/or TRPA1 receptors.
Acetanilides ; pharmacology ; Action Potentials ; Animals ; Capsaicin ; analogs & derivatives ; pharmacology ; Formaldehyde ; pharmacology ; Ganglia, Spinal ; physiology ; Nociceptors ; physiology ; Pain ; physiopathology ; Pain Measurement ; Patch-Clamp Techniques ; Purines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; TRPV Cation Channels ; physiology

The effects of intrarenal artery injection of capsaicin on multi- and single-unit spontaneous discharges of renal afferent nerve fibers were investigated in anesthetized rabbits. The results obtained are as follows: (1) intrarenal artery injection of capsaicin (20, 40, and 60 nmol/kg) increased the renal afferent nerve activity (ARNA) in a dose-dependent manner with unchanged arterial pressure; (2) pretreatment with ruthenium red (40 mmol/kg), a capsaicin receptor antagonist, completely abolished the effect of capsaicin; and (3) pretreatment with a nitric oxide synthase inhibitor L-NAME (N(6)-nitro-L-arginine methylester, 0.1 mmol/kg), significantly enhanced the ARNA response to capsaicin. The results suggest that intrarenal artery injection of capsaicin can activate ARNA via capsaicin receptors in anesthetized rabbits and that nitric oxide may be involved in regulating the activity of renal sensory nerve fibers as an inhibitory neurotransmitter.
Animals ; Capsaicin ; pharmacology ; Dose-Response Relationship, Drug ; Electrophysiology ; Female ; Injections, Intra-Arterial ; Kidney ; innervation ; Male ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; pharmacology ; Rabbits ; Ruthenium Red ; pharmacology ; Visceral Afferents ; physiology

OBJECTIVETo investigate the vasodilating effect of capsaicin (CAP) on rat mesenteric artery and its mechanism.

METHODSThe third branch of the superior mesenteric artery in male Sprague-Dawley rat (250-350 g) was excised, the periadventitial fat and connective tissue were removed and the mesenteric artery was dissected into 2 mm rings. Each ring was placed in a 5 ml organ bath of DMT 610M system and the tension was recorded.

RESULTSCAP (10(-9)-10(-5) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine (10(-5) mol/L), and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Pretreatment with either L-NAME (3 X10(-4) mol/L), an inhibitor of nitric oxide synthase(NOS), or CGRP8-37 (2 X 10(-6) mol/L), an antagonist of calcitonin gene-related peptide (CGRP), for 30 min significantly attenuated the relaxation of endothelium-intact mesenteric artery induced by CAP. CGRP (10(-10)-3 X10(-8) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine, and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Substance P did not relax the mesenteric artery pre-constricted by phenylephrine.

CONCLUSIONCAP has partial endothelium-dependent relaxation effect on rat mesenteric artery, which may be mediated by activating the endothelial NOS-NO pathway. The endothelium-independent relaxation in rat mesenteric artery induced by CAP may be mediated by CGRP.

Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Capsaicin ; pharmacology ; In Vitro Techniques ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Peptide Fragments ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects

AIMTo investigate the effect of capsaicin on IA and IK in cultured rat trigeminal ganglion (TG) neurons.

METHODSWhole-cell patch clamp technique was used to record the IA and IK before and after capsaicin perfusion at different concentrations.

RESULTSIn capsaicin-sensitive (CS) neurons, capsaicin was shown to selectively inhibit IA in dose-dependent manner, the IC50 was 0.99 micromol x L(-1). Yet capsaicin showed no inhibitory effect on IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IK by 13.2%. In capsaicin-insensitive (CIS) neurons, capsaicin (1 micromol x L(-1)) showed no significant inhibitory effect on IA and IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IA and IK by 16.8% and 15.3%, respectively. Neither 1 micromol x L(-1) nor 10 micromol x L(-1) capsaicin showed effect on the G-V curve of IA and IK.

CONCLUSIONCapsaicin was found to selectively inhibit the IA current in CS neurons, and this effect may contribute to hyperalgesia when capsaicin was first used.

Animals ; Capsaicin ; pharmacology ; Cells, Cultured ; Female ; Male ; Neurons ; physiology ; Patch-Clamp Techniques ; Potassium Channels, Voltage-Gated ; drug effects ; Rats ; Rats, Sprague-Dawley ; Trigeminal Ganglion ; cytology ; physiology

BACKGROUND: Body temperature is usually regulated by opposing controls of heat production and heat loss. However, systemic administration of capsaicin, the pungent ingredient of hot peppers, facilitated heat production and heat loss simultaneously in rats. We recently found that the capsaicin-induced heat loss and heat production occur simultaneously and that the biphasic change in body temperature is a sum of transient heat loss and long-lasting heat production. Moreover, suppression of the heat loss response did not affect capsaicin-induced heat production and suppression of heat production did not affect capsaicin-induced heat loss. These observations suggest the independent peripheral mechanisms of capsaicin-induced thermal responses. Thus, the capsaicin-induced thermal responses apparently lack an integrated control. METHODS: Male Wistar rats were maintained at an ambient temperature of 24 1 degrees C on a 12 h on-off lighting schedule at least for two weeks before the experiments. They were anesthetized with urethane (1.5 g/kg, i.p.) and placed on a heating pad, which was kept between 29 and 30 degrees C. Skin temperature(Ts) was measured with a small thermistor, which was taped to the dorsal surface of the rat's tail, to assess vasoactive changes indirectly. Colonic temperature(Tc) was measured with another thermistor inserted about 60 mm into the anus. O2 consumption was measured by the open-circuit method, and values were corrected for metabolic body size (kg0.75). Capsaicin (Sigma) was dissolved in a solution comprising 80+ACU- saline, 10+ACU- Tween 80, and 10+ACU- ethanol, and injected subcutaneously at a dose of 5 mg/kg. Each rat received a single injection of capsaicin because repeated administration of capsaicin renders an animal insensitive to the subsequent administration of capsaicin. Laminectomy was performed at the level of the first and second cervical vertebrae to expose the cervical spinal cord for sectioning. The brain was transected at 4-mm rostral from the interaural line with an L-shaped knife. RESULTS: After administration of capsaicin, O2 consumption increased from 13.5 0.4 mL/min/kg0.75 at 0 min to a peak of 15.9 0.4 mL/min/kg0.75 at 71 min and gradually declined but remained higher than the basal value until the end of the 4-h observation period. Ts also immediately increased from 27.7 0.2 degrees C to 31.9 0.3 degrees C at 39 min, and it returned to the baseline level within 90 min after the capsaicin administration. Tc initially decreased from 37.1 0.1 degrees C to 36.8 0.2 degrees C at 43 min and then gradually increased over the baseline level and remained at 37.6 0.2 degrees C until the end of the experiment. In spinalized rats, the capsaicin-induced increases in O2 consumption was largely attenuated, while the basal O2 consumption was similar to that of control rats. The basal Ts of spinalized rats was 32.4 0.3 degrees C, which was higher than that of control rats. Capsaicin increased Ts by less than 1 degree C, and Tc did not change after the capsaicin administration. O2 consumption of decerebrated rats was statistically higher than that of control rats after the injection of capsaicin. However, capsaicin did not increase Ts, showing a lack of a vasodilatory response. Decerebration between the hypothalamus and midbrain prevented the capsaicin-induced heat loss but not the heat production response. CONCLUSION: These results show that the capsaicin-induced heat production and heat loss are controlled separately by the brainstem and by the forebrain, respectively, and suggest that the body temperature regulation is performed without an integrative center.
Animal ; Body Temperature Regulation/drug effects+ACo- ; Brain/physiology ; Brain/drug effects ; Capsaicin/pharmacology+ACo- ; Decerebrate State ; Male ; Oxygen Consumption/drug effects ; Rats ; Rats, Wistar

OBJECTIVETo observe the effect of capsaicin on the secretion of the transferred gland in "latent period".

METHODSForty-two patients (45 sides of eye), who received the microvascular autologous submandibular gland transfer in our hospital, were treated with two different types of capsaicin stimulations. The secretion function of the transferred glands was evaluated by Schirmer's test. The effect of capsaicin and its time-variation regularity were observed. In the meantime, the results of capsaicin were compared with some other stimulation methods, such as acid, chewing and physiotherapy with infrared rays.

RESULTSThe capsaicin gargle, capsaicin cream and physiotherapy could all promote the secretion of the transferred gland, while the effects of the capsaicin stimulation were more obvious. The other two stimulations (acid and chewing) had no effect on the secretion of the transferred gland.

CONCLUSIONSThe capsaicin stimulation can be taken as one of the effective means to promote the secretion of the transferred glands in "latent period" and to prevent the obstruction of the ducts. Because of its convenience and blandness, the capsaicin cream is the first choice of the clinical application options for the transferred submandibular gland in "latent period".

Adolescent ; Adult ; Capsaicin ; pharmacology ; Child ; Female ; Humans ; Keratoconjunctivitis Sicca ; surgery ; Male ; Middle Aged ; Saliva ; secretion ; Submandibular Gland ; secretion ; transplantation ; Transplantation, Autologous ; Young Adult

OBJECTIVETo study the mechanisms of capsaicin-induced apoptosis of human melanoma A375-S2 cells.

METHODSMTT assay, fluorescence microscopy, DNA agarose gel electrophoresis, flow cytometry and Western blot analysis were carried out to assess the morphological and biochemical changes of A375-S2 cells after capsaicin treatment.

RESULTSCapsaicin induced A375-S2 cell death in a time- and dose-dependent manner. Sub-diploid peak was seen at 24 h after 250 micromol/L capsaicin treatment, and apoptotic bodies and DNA ladder were observed at 36 h after capsaicin treatment. The expression of inhibitor of caspase activated DNase (ICAD) was reduced with the lapse of time.

CONCLUSIONCapsaicin induces A375-S2 cell apoptosis and down-regulation of ICAD contributes to this process.

Antineoplastic Agents, Phytogenic ; pharmacology ; Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; biosynthesis ; Capsaicin ; pharmacology ; Caspases ; metabolism ; Cell Line, Tumor ; Dose-Response Relationship, Drug ; Humans ; Melanoma ; pathology ; Signal Transduction ; Skin Neoplasms ; pathology