[Research progress of oral erythroplakia]

Oral erythroplakia is an rare oral disorder with relatively high potential of becoming malignant. It has a lower prevalence but a higher malignant transformation rate than oral leukoplakia. The etiology and pathogenesis of the disease is so far not clear, but several studies have pointed to tobacco chewing, tobacco smoking, and betel quid chewing with or without tobacco and alcohol usage as etiologic factors.The treatment methods are mainly surgical excision operations as well as laser treatment. However, the recurrence rate and the malignant transformation rate of oral erythroplakiaare high, thus long-term close follow-up is needed. In the present article, the definition, epidemiological characteristics, clinical manifestations, histopathological characteristics, etiology and pathogenesis, diagnosis, treatment and prognosis of oral erythroplakiaare reviewed.

[Effects of titanium dioxide nanoparticles and lipopolysaccharide on antioxidant function of liver tissues in mice]

OBJECTIVE

To compare the effects of different sized titanium dioxide (titanium dioxide, TiO₂) on the antioxidant function of liver tissues in mice, and study the effect of TiO₂ nanoparticles on the susceptibility of lipopolysaccharide (LPS) on liver tissues.

METHODS

Ninety 4-week-old clean-grade male ICR mice were divided into 18 groups, in which the mice were fed for different feed involving ordinary feed, nanometer TiO₂ feed which meant the feed including 1% (mass fraction) TiO₂ nanoparticles, and submicron TiO₂ feed which meant the feed including 1% (mass fraction) TiO₂ submicron particles. Respectively, they were fed for 1 month, 3 months and 6 months. On the second day after the feeding, respectively, 0 and 10 mg/kg LPS were given by gavage. The mice were harvested after 4 h and the body weight and liver weight for calculating the liver coefficient were recorded. Then the liver tissue homogenates were prepared for determining the antioxidant indexes including the total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA).

RESULTS

The change of body weight in mice was only discovered in group fed for 1 month, which showed significant decrease of body weight in treatment groups compared with control group. And there was no significant change of the liver coefficient in each group. Compared with control groups, nanometer TiO₂ groups and submicron TiO₂ group, the activity of T-AOC, T-SOD and MDA of nanometer TiO₂+LPS group and submicron TiO₂+LPS group in which the mice were fed for 1 month and 6 months increased in different degree. And another result was also existing. The MDA activity of liver in different sized treatment groups fed for 3 months decreased. Neither significant difference between the results of different sized TiO₂ treatment groups, nor significant difference among different sized TiO₂ groups and the control groups were observed.

CONCLUSION

Longterm peroral TiO₂ nanoparticles and TiO₂ submicron particles are more likely to cause damage to the liver in the growing mice, and the damage may be either reductive or oxidative. In addition, small sized TiO₂ can increase the susceptibility of mice liver to LPS and the susceptibility will increase with the increase of exposure time.

UPLC/ESI-QTOF-MS-based metabolomics survey on the toxicity of triptolide and detoxication of licorice

Triptolide (TP) from Tripterygium wilfordii has been demonstrated to possess anti-inflammatory, immunosuppressive, and anticancer activities. TP is specially used for the treatment of awkward rheumatoid arthritis, but its clinical application is confined by intense side effects. It is reported that licorice can obviously reduce the toxicity of TP, but the detailed mechanisms involved have not been comprehensively investigated. The current study aimed to explore metabolomics characteristics of the toxic reaction induced by TP and the intervention effect of licorice water extraction (LWE) against such toxicity. Obtained urine samples from control, TP and TP + LWE treated rats were analyzed by UPLC/ESI-QTOF-MS. The metabolic profiles of the control and the TP group were well differentiated by the principal component analysis and orthogonal partial least squares-discriminant analysis. The toxicity of TP was demonstrated to be evolving along with the exposure time of TP. Eight potential biomarkers related to TP toxicity were successfully identified in urine samples. Furthermore, LWE treatment could attenuate the change in six of the eight identified biomarkers. Functional pathway analysis revealed that the alterations in these metabolites were associated with tryptophan, pantothenic acid, and porphyrin metabolism. Therefore, it was concluded that LWE demonstrated interventional effects on TP toxicity through regulation of tryptophan, pantothenic acid, and porphyrin metabolism pathways, which provided novel insights into the possible mechanisms of TP toxicity as well as the potential therapeutic effects of LWE against such toxicity.

Effects of sulfur-fumigation on the pharmacokinetics, metabolites and analgesic activity of Radix Paeoniae Alba

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Paeoniae Alba (Baishao, BS), one of the most commonly used traditional Chinese medicinal herbs, has many pharmacological effects including analgesic activity. Previous studies found that sulfur-fumigation, a post-harvest handling process developed to prevent mold contamination of medicinal herbs, altered the quality of BS. However, whether sulfur-fumigation affects the pharmacokinetics, safety and efficacy of BS warrants further investigation.

AIM OF THE STUDY

To evaluate the feasibility of sulfur-fumigation as a post-harvest handling process of BS from the viewpoints of pharmacokinetics, safety and efficacy.

MATERIALS AND METHODS

The pharmacokinetic behaviors of four active components of BS and one characteristic component of sulfur-fumigated BS (S-BS) were evaluated by high performance liquid chromatography triple quadrupole mass spectrometry (HPLC-TQ-MS/MS). The safety was investigated using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS) based metabolomics approach after intragastric (i.g.) administration of non-fumigated BS (N-BS) and S-BS in rats. The analgesic efficacy was compared using hot-plate test in mice, after i.g. administration of N-BS and S-BS, at both high and low dosages.

RESULTS

Systemic exposures of paeoniflorin and oxypaeoniflorin, two analgesic components of BS, were significantly decreased in the S-BS treated group compared to the N-BS treated group, while paeoniflorin sulfonate, one of the sulfur-containing derivatives of S-BS, was detected in all time-points of S-BS treated group with the area under the plasma concentration-time curve (AUC_0-t) and the maximum plasma concentration (C_max) as high as 7077.06 ± 2232.97ng/mL*h and 1641.42 ± 634.79ng/mL respectively, which indicated that sulfur-fumigation altered the pharmacokinetic behaviors of BS. Besides, paeoniflorin sulfonate and its four metabolites with ambiguous toxicities, as well as one endogenous metabolite p-cresol glucuronide, the biomarker of disordered homeostasis of intestinal bacteria and bile acid, were identified as the characteristic metabolites in S-BS administered rats, suggesting that sulfur-fumigation reduced the safety of BS. Furthermore, the analgesic effects at both low and high dosages were decreased in different extent when compared to N-BS administered groups, indicating that sulfur-fumigation weakened the efficacy of BS.

CONCLUSION

Sulfur-fumigation altered the pharmacokinetics, as well as reduced the safety and efficacy of BS, suggesting that sulfur-fumigation is not recommended for post-harvest handling of BS.

Sulfur dioxide residue in sulfur-fumigated edible herbs: The fewer, the safer?

The residual content of sulfur dioxide is frequently regarded as the exclusive indicator in the safety evaluation of sulfur-fumigated edible herbs. To examine the feasibility of such assessment criteria, here the variations in residual sulfur dioxide content during sulfur-fumigation and the potential mechanisms involved were investigated, using Angelicae Sinensis Radix (ASR) as a model herb. The residual sulfur dioxide content and ten major bioactive components in sulfur-fumigated ASR samples were dynamically examined at 13 successive time points within 72 h sulfur-fumigation. The relationship between the content variation tendency of sulfur dioxide and the ten chemicals was discussed. The results suggested that sulfur dioxide-involved chemical transformation of the original components in ASR might cause large consumption of residual sulfur dioxide during sulfur-fumigation. It implies that without considering the induced chemical transformation of bioactive components, the residual sulfur dioxide content alone might be inadequate to comprehensively evaluate the safety of sulfur-fumigated herbs.

Presynaptic inhibition of GABAergic synaptic transmission by adenosine in mouse hypothalamic hypocretin neurons

Hypocretin neurons in the lateral hypothalamus, a new wakefulness-promoting center, have been recently regarded as an important target involved in endogenous adenosine-regulating sleep homeostasis. The GABAergic synaptic transmissions are the main inhibitory afferents to hypocretin neurons, which play an important role in the regulation of excitability of these neurons. The inhibitory effect of adenosine, a homeostatic sleep-promoting factor, on the excitatory glutamatergic synaptic transmissions in hypocretin neurons has been well documented, whether adenosine also modulates these inhibitory GABAergic synaptic transmissions in these neurons has not been investigated. In this study, the effect of adenosine on inhibitory postsynaptic currents (IPSCs) in hypocretin neurons was examined by using perforated patch-clamp recordings in the acute hypothalamic slices. The findings demonstrated that adenosine suppressed the amplitude of evoked IPSCs in a dose-dependent manner, which was completely abolished by 8-cyclopentyltheophylline (CPT), a selective antagonist of adenosine A1 receptor but not adenosine A2 receptor antagonist 3,7-dimethyl-1-(2-propynyl) xanthine. A presynaptic origin was suggested as following: adenosine increased paired-pulse ratio as well as reduced GABAergic miniature IPSC frequency without affecting the miniature IPSC amplitude. Further findings demonstrated that when the frequency of electrical stimulation was raised to 10 Hz, but not 1 Hz, a time-dependent depression of evoked IPSC amplitude was detected in hypocretin neurons, which could be partially blocked by CPT. However, under a higher frequency at 100 Hz stimulation, CPT had no action on the depressed GABAergic synaptic transmission induced by such tetanic stimulation in these hypocretin neurons. These results suggest that endogenous adenosine generated under certain stronger activities of synaptic transmissions exerts an inhibitory effect on GABAergic synaptic transmission in hypocretin neurons by activation of presynaptic adenosine A1 receptors, which may finely regulate the excitability of these neurons as well as eventually modulate the sleep-wakefulness.

[Glutamate-related mechanism of ginsenosides against anoxic-ischemic brain damage]

AIM AND METHODS

To observe the antagonist effect of ginsenosides upon excitatory neurotoxicity of glutamate in rat hippocampal slices, and to observe the inhibitory and facilitated effects of ginsenosides upon glutamate release from cultured mice cortical neurons and upon glutamate uptake by cultured astrocytes, respectively, during simulated ischemia, in order to elucidate whether the protective effect of ginsenosides against anoxic-ischemic brain damage is related to reducing the excitatory neurotoxicity of glutamate.

RESULTS

The orthodromic population spikes (OPS) recorded in hippocampal slice decreased in amplitude and disappeared finally during 20-min glutamate (1 mmol/L) exposure, and recovered less 1 h after the end of this exposure. However, OPS recovered well after the use of ginsenosides at different concentrations, especially at 20 microg/ml. In cultured mice cortical neurons and astrocytes, glutamate released from neurons up to several times of control and its uptake by astrocytes decreased markedly during simulated ischemia, ginsenosides (20 microg/ml) could significantly inhibit glutamate release from neurons and facilitate glutamate uptake by astrocytes during the same ischemia exposure.

CONCLUSIONS

Reducing the excitatory neurotoxicity of glutamate may be an important mechanism of ginsenosides against anoxic-ischemic brain damage.

[Increased expression of formalin-induced Fos and NADPH-d positive neurons in the spinal cord of morphine-tolerant rats]

Fos immunocytochemistry, NADPH-d histochemistry and Fos/NADPH-d double-labeling method were used to study the changes in formalin-induced Fos, NADPH-d positive and Fos/NADPH-d double-labeled neurons in the spinal cord of morphine-tolerant rats. Formalin-induced Fos-like immunoreactivity (Fos-LI) was located in the superficial laminae and neck of ipsilateral spinal cord. Acute administration of morphine decreased the expression of Fos-LI in non-tolerant rats, while the expression of Fos-LI was significantly increased in morphine-tolerant rats. Fos-LI was distributed not only in the whole laminae of the ipsilateral spinal cord but also in the contralateral spinal cord. Acute administration of morphine was ineffective in decreasing the expression of Fos-LI in morphine-tolerant rats. Morphine tolerance increased the expression of formalin-induced NADPH-d positive neurons in the superficial laminae of spinal dorsal horn. A few formalin-induced Fos/NADPH-d double-labeled neurons were detected in the superficial laminae of spinal dorsal horn of non-tolerant rats. In morphine-tolerant rats, on the other hand, formalin-induced Fos/NADPH-d double-labeled neurons were increased and distributed in the whole laminae of the ipsilateral spinal cord and the contralateral superficial spinal cord. It is suggested that NO is involved in the increase of formalin-induced Fos-LI in the spinal cord of morphine-tolerant rats and may play an important role in the development of morphine tolerance.

Microprocessor-programmed infusion of theophylline rapidly attained expected steady-state level in rabbit plasma

A self-made microprocessor-programmed (two-compartmental model) infusion controller was connected with an infusion pump, which achieved an expected steady-state plasma concentration (Cpss) rapidly (5 T1(2)alpha) and maintained the level. Theophylline was selected as an example, and its pharmacokinetic parameters of rabbits, expected Cpss, body weight (wt), and infusion time (t) were input. The programmed infusion rate (Kt) was determined by the following equation: (Kt) = Cpss.K10.Vc.wt (1 + [(K21-beta)/beta]EXP(-K21t)) and the predicted value was calculated by the formula: C(t) = Cpss X [1-EXP(-alpha t)]. The needed concentration and total volume of drug were automatically shown on the screen. The drug was automatically infused after pumping, and the plasma concentration of theophylline was measured by colorimetric method. The results showed that the median absolute value of the performance error (MAVPE) was 8.3%. Although T1(2)beta of theophylline was 6.08 h, the expected Cpss was attained in only 30 min (5 T1(2)alpha) after start of infusion and then well maintained.

[Neurotensin excited neurons of the dorsal motor vagal nucleus: an in vitro study]

Intracellular recordings were made from neurons of the dorsal motor nucleus of the vagus (DMV) in rat brain slices. Most of DMV neurons (88%) were depolarized by droplets or perfusion of neurotensin (NT) in a dose-dependent manner. The depolarization, accompanied by an increase in membrane resistance, depended on extracellular K+ concentration and reversed polarity at about -82 mV. Perfusion with Ca(2+)-free/high-Mg2+ solution or with 1 mumol/L TTX solution, which blocked synaptic activities, did not eliminate NT-induced depolarization. The results indicate that NT excites DMV neurons through postsynaptic mechanism and this exciting depolarization may result from a decrease in K+ conductance.

Hyperpolarizing action of enkephalin on neurons in the dorsal motor nucleus of the vagus, in vitro

Intracellular recordings were made from neurons of the dorsomotor vagal nucleus (DMV) in slices of rat medulla oblongata. [D-Ala2, D-Leu5]-enkephalin (DADLE), applied by perfusion (0.01-3 microM) or droplets, dose-dependently hyperpolarized 85% of the DMV neurons tested. The hyperpolarization, associated with a decrease in membrane resistance, persisted after elimination of synaptic activity by perfusion with Ca2(+)-free/high-Mg2+ solution or with 1 microM TTX solution. The opioid antagonist, naloxone, reversibly inhibited DADLE-induced hyperpolarization. The hyperpolarization depended on extracellular K+ concentration and reversed at about -90 mV. DADLE also decreased Ca2(+)-dependent spike duration and after-hyperpolarization (AHP). DAGO (a selective mu-receptor agonist), but not DPLPE (a selective delta-receptor agonist), mimicked DADLE's effects on membrane potential, Ca2(+)-dependent spike duration, and AHP. It is concluded that DADLE, through postsynaptic mu-type opioid receptors, hyperpolarized DMV neurons by increasing K+ conductance, which may have an inhibitory effect on DMV output. DADLE-induced decrease of spike duration and AHP was also mediated by mu-receptors and could have additional effects on functions of the DMV neuron by virtue of reduction in Ca2+ entry.

Glutamate modulates dopamine release in the striatum as measured by brain microdialysis

Brain microdialysis plus high performance liquid chromatography and electrochemical detection were employed to study whether glutamate exerts direct presynaptic facilitation of dopamine (DA) release in the rat striatum. The perfusion of the dialysis probe with high-K+ Ringer solution (70 mM) increased DA and glutamate release 380.6 +/- 69.2% and 323.0 +/- 46.6% of preperfusion levels, respectively. Perfusion of 1 mM glutamate stimulated DA release by 250.7 +/- 30.6%, and coadministration of 2 mM glutamic acid diethylester (glutamate receptor blocking agent) significantly antagonized the glutamate response. The present results indicate presynaptic facilitation of the release of DA in the striatum by glutamate.