Midgut-based resistance to oral infection by a nucleopolyhedrovirus in the laboratory-selected strain of the smaller tea tortrix, Adoxophyes honmai (Lepidoptera: Tortricidae).

A strain of Adoxophyes honmai resistant to Adoxophyes honmai nucleopolyhedrovirus (AdhoNPV) was established from a field-collected colony by repeated selection. Fifth-instar larvae of this resistant strain (R-strain) had over 66 666-fold greater resistance in terms of 50 % lethal concentration values to oral infection of AdhoNPV than non-selected strain larvae (susceptible for AdhoNPV; S2-strain). In this study, the mechanism of resistance to AdhoNPV was determined in R-strain larvae. An assessment of viral genome replication in AdhoNPV-infected S2- and R-strain larvae by quantitative PCR showed no viral genome replication occurring in R-strain larvae. Transcription of AdhoNPV ie-1, vp39 and polyhedrin genes was also not detected in R-strain midgut cells. Besides, a fluorescent brightener had no effect on AdhoNPV infection in either S2- or R-strain. However, binding and fusion of occlusion-derived virus with R-strain were significantly lower than those of S2-strain. These findings suggest that R-strain Adoxophyeshonmai larvae possess a midgut-based resistance to oral infection by AdhoNPV in which midgut epithelial cells are infected less efficiently.

Resveratrol attenuates inflammation-induced hyperexcitability of trigeminal spinal nucleus caudalis neurons associated with hyperalgesia in rats.

BACKGROUND: Resveratrol, a component of red wine, has been reported to decrease prostaglandin E2 production by inhibiting the cyclooxygenase-2 cascade and to modulate various voltage-dependent ion channels, suggesting that resveratrol could attenuate inflammatory hyperalgesia. However, the effects of resveratrol on inflammation-induced hyperexcitability of nociceptive neurons in vivo remain to be determined. Thus, the aim of the present study was to determine whether daily systemic administration of resveratrol to rats attenuates the inflammation-induced hyperexcitability of spinal trigeminal nucleus caudalis wide-dynamic range neurons associated with hyperalgesia. RESULTS: Inflammation was induced by injection of complete Freund's adjuvant into the whisker pad. The threshold of escape from mechanical stimulation applied to whisker pad in inflamed rats was significantly lower than in control rats. The decreased mechanical threshold in inflamed rats was restored to control levels by daily systemic administration of resveratrol (2 mg/kg, i.p.). The mean discharge frequency of spinal trigeminal nucleus caudalis wide-dynamic range neurons to both nonnoxious and noxious mechanical stimuli in inflamed rats was significantly decreased after resveratrol administration. In addition, the increased mean spontaneous discharge of spinal trigeminal nucleus caudalis wide-dynamic range neurons in inflamed rats was significantly decreased after resveratrol administration. Similarly, resveratrol significantly diminished noxious pinch-evoked mean after discharge frequency and occurrence in inflamed rats. Finally, resveratrol restored the expanded mean size of the receptive field in inflamed rats to control levels. CONCLUSION: These results suggest that chronic administration of resveratrol attenuates inflammation-induced mechanical inflammatory hyperalgesia and that this effect is due primarily to the suppression of spinal trigeminal nucleus caudalis wide dynamic range neuron hyperexcitability via inhibition of both peripheral and central cyclooxygenase-2 cascade signaling pathways. These findings support the idea of resveratrol as a potential complementary and alternative medicine for the treatment of trigeminal inflammatory hyperalgesia without side effects.

Systemic administration of resveratrol suppress the nociceptive neuronal activity of spinal trigeminal nucleus caudalis in rats.

Although a modulatory role has been reported for the red wine polyphenol resveratrol on several types of ion channels and excitatory synaptic transmission in the nervous system, the acute effects of resveratrol in vivo, particularly on nociceptive transmission of the trigeminal system, remain to be determined. The aim of the present study was to investigate whether acute intravenous resveratrol administration to rats attenuates the excitability of wide dynamic range (WDR) spinal trigeminal nucleus caudalis (SpVc) neurons in response to nociceptive and non-nociceptive mechanical stimulation in vivo. Extracellular single unit recordings were made from 18 SpVc neurons in response to orofacial mechanical stimulation of pentobarbital-anesthetized rats. Responses to both non-noxious and noxious mechanical stimuli were analyzed in the present study. The mean firing frequency of SpVc WDR neurons in response to both non-noxious and noxious mechanical stimuli was inhibited by resveratrol (0.5-2 mg/kg, i.v.) and maximum inhibition of the discharge frequency of both non-noxious and noxious mechanical stimuli was seen within 10 min. These inhibitory effects were reversed after approximately 20 min. The relative magnitude of inhibition by resveratrol of SpVc WDR neuronal discharge frequency was significantly greater for noxious than non-noxious stimulation. These results suggest that, in the absence of inflammatory or neuropathic pain, acute intravenous resveratrol administration suppresses trigeminal sensory transmission, including nociception, and so resveratrol may be used as a complementary and alternative medicine therapeutic agent for the treatment of trigeminal nociceptive pain, including hyperalgesia.

Green tea intake, MTHFR/TYMS genotype and breast cancer risk: the Singapore Chinese Health Study.

The tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) has been reported to act as a cancer preventive agent through folate pathway inhibition in experimental studies. We hypothesized that if folate pathway inhibition is the mechanism of cancer preventive activities of EGCG, then the protective effect against breast cancer would be stronger among women with low dietary folate intake and the high-activity methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TYMS) genotypes. In a nested case-control study of 380 women with incident breast cancer and 662 controls within the Singapore Chinese Health Study, we found no association between either green tea intake or gene polymorphisms of MTHFR (C677T and A1298C) and TYMS (1494 ins/del) and breast cancer risk. However, among women with low folate intake (<133.4 microg/day), weekly/daily green tea intake was inversely associated with breast cancer risk compared with less green tea intake [odds ratio (OR) = 0.45, 95% confidence interval (CI) = 0.26-0.79, P for interaction = 0.02]. Among women with high folate intake (>or=133.4 microg/day), green tea intake was not associated with breast cancer. Similarly, among women possessing the high-activity MTHFR/TYMS genotypes (0-1 variant allele), weekly/daily versus less frequent green tea intake was associated with lower breast cancer risk (OR = 0.66, 95% CI = 0.45-0.98), which was observed even more strongly among those who also had low folate intake (OR = 0.44, 95% CI = 0.22-0.89) than high folate intake (OR = 0.92, 95% CI = 0.55-1.54). This association was not observed among women possessing the low-activity genotypes (2-4 variant alleles). Our findings suggest that folate pathway inhibition may be one mechanism through which green tea protects against breast cancer in humans.

Quantitative analysis of the ultrasonic vocalization responses elicited in adjuvant-induced arthritic rats for screening analgesic drugs.

Adjuvant-induced arthritic (AIA) rats have been developed as a chronic pain model to evaluate the effects of analgesic drugs. The purpose of the present study was to examine whether there is dose-dependent inhibition of the emission of ultrasonic vocalization (USV) responses by analgesic drugs in AIA rats. It was demonstrated that morphine (1.25-5.0 mg/kg, s.c.) and ketoprofen (2.5-10.0 mg/kg, s.c.) dose-dependently inhibit USV responses. These results suggest that the USV responses elicited in AIA rats are useful for the quantitative evaluation of analgesic drugs.

Ultrasonic vocalization response elicited in adjuvant-induced arthritic rats as a useful method for evaluating analgesic drugs.

Adjuvant-induced arthritic (AIA) rats develop a severe chronic polyarthritis which shares some features in common with human rheumatoid arthritis. The purpose of the present study was to examine whether AIA rats emit ultrasonic vocalizations (USVs) when they are confronted with a healthy 'stimulus rat' in social interactions. We also examined the effects of three analgesic drugs (piroxicam, rofecoxib and ketoprofen) on USV responses using the same paradigm. In social interactions, AIA rats and intact controls emitted USVs in the 22-28 kHz range. Vocalization activities were significantly higher in AIA rats than those in intact controls. Moreover, the USVs of AIA rats were significantly inhibited by the three analgesic drugs. These results suggest that the USV responses elicited in AIA rats are useful for the evaluation of analgesic drugs.