Biomedical subjects

Lihua Shen

Publications and source records attributed to Lihua Shen.

8 recordsLinked to original sources

PubMed2006

Norlaudanosoline and nicotine increase endogenous ganglionic morphine levels: nicotine addiction.

1. Given the presence of morphine, its metabolites and precursors, e.g., norlaudanosoline, in mammalian and invertebrate tissues, it became important to determine if exposing normal excised ganglia to norlaudanosoline would result in increasing endogenous morphine levels. 2. Mytilus edulis pedal ganglia contain 2.2 +/- 0.41 ng/g wet weight morphine as determined by high pressure liquid chromatography coupled to electrochemical detection and radioimmunoassay. 3. Incubation of M. edulis pedal ganglia with norlaudanosoline, a morphine precursor, resulted in a concentration- and time-dependent statistical increase in endogenous morphine levels (6.9 +/- 1.24 ng/g). 4. Injection of animals with nicotine also increased endogenous morphine levels in a manner that was antagonized by atropine, suggesting that nicotine addiction may be related to altering endogenous morphine levels in mammals. 5. We surmise that norlaudanosoline is being converted to morphine, demonstrating that invertebrate neural tissue can synthesize morphine.

Animals↗

PubMed2005

In vivo and in vitro L-DOPA and reticuline exposure increases ganglionic morphine levels.

BACKGROUND: Given the presence of morphine, its metabolites and precursors, i.e., reticuline, in mammalian and invertebrate tissues, it has become imperative to determine if exposing tissues to putative opiate alkaloid and dopamine precursors would result in increasing endogenous morphine levels. MATERIAL/METHODS: Endogenous morphine levels were determined by high performance liquid chromatography coupled to electrochemical detection and radioimmunoassay, following incubation of Mytilus edulis pedal ganglia with reticuline or L-DOPA. Injection of L-DOPA or reticuline into healthy animals was via the foot. RESULTS: Ganglia incubated in vitro with reticuline or L-DOPA for 1 hour exhibited a concentration and time dependent statistically significant increase in their endogenous morphine levels (5.0 +/- 0.47, 3.6 +/- 0.45 ng/ganglion, respectively). Injection of intact, healthy animals with reticuline or L-DOPA also results in significantly higher endogenous ganglionic morphine levels. CONCLUSIONS: Taken together, we show that L-DOPA is being converted to morphine, demonstrating that pedal ganglia can synthesize morphine from these putative precursors in vitro and in vivo. This is the first demonstration of morphine being synthesized in a normal, healthy free living animal.

Alkaloids↗

PubMed2005

[Terpenoids in root exudates of different allelopathic rice varieties].

In this paper, a strong allelopathic rice variety PI312777 and a weak allelopathic rice variety Lemont were used as test materials, and the root exudates of two rice varieties grown in the media of sand and soil were respectively collected by using circulation system approach. The terpenoids in ether-extracts were detected by GC-MS, and characterized by spectrum database. The results showed that some terpenoids such as limonene oxide, limonene dioxide, carvone oxide, carveol, and cedrol were detected in the ether-extracts. Different rice varieties had the similar kinds of terpenoids, but their existing modes and quantities were different. The differences between different various cultural methods and between rice varieties were further discussed.

Oryza↗

PubMed2005

[Interactive effects between allelochemical substitutes].

In order to understand the allelopathic mechanisms of rice on weed, the allelochemical substitutes salicylic acid, p-hydroxybenzonic acid, cinnamic acid, vanillic acid and ferulic acid were used in an orthogonally gyrating regression experiment to study their interactive effects on the growth of barnyardgrass. The results indicated that whether the interactive effects between two substitutes, e.g., between salicylic and cinnamic acid or between salicylic and p-hydrobanzonic acid, were synergistic or antagonistic depended on the concentrations of each substitutes in the mixture. In the mixture of salicylic acid and p-hydrobanzonic acid, the effect of salicylic acid was synergistic at < 0.14 mmol.L(-1) but antagonistic at > 0.14 mmol.L(-1), while p-hydrobanzonic acid showed an antagonistic effect at > 0.425 mmol.L(-1). Salicylic acid at all test concentrations exhibited antagonism to cinnamic acid, while cinnamic acid had a synergistic at < 0.14 mmol.L(-1), but an antagonistic effect at >0.14 mmol.L(-1) on alicylic acid. The interactive effects between cinnamic and ferulic acid were all synergistic at test concentrations.

Cinnamates↗

PubMed2005

Tyrosine and tyramine increase endogenous ganglionic morphine and dopamine levels in vitro and in vivo: cyp2d6 and tyrosine hydroxylase modulation demonstrates a dopamine coupling.

BACKGROUND: The ability of animals to make morphine has been in question for the last 30 years. Studies have demonstrated that animals do contain morphine precursors and metabolites, as well as the ability to use some morphine precursors to make morphine. MATERIAL/METHODS: The present study uses excised ganglia from the marine invertebrate Mytilus edulis as well as whole animals. Morphine and dopamine levels were determined by high performance liquid chromatography coupled to electrochemical detection and radioimmunoassay. Tissues and whole animals were also exposed to morphine precursors and exposed to the CYP2D6 inhibitor quinidine and the tyrosine hydroxylase inhibitor alpha-methyl-para-tyrosine (AMPT). Additionally, via RT-PCR, a cDNA fragment of the CYP2D6 enzyme in the ganglia of M. edulis was identified. RESULTS: Pedal ganglia incubated with either tyramine or tyrosine, or whole animals receiving injections, exhibited a statistically significant concentration- and time-dependent increase in their endogenous morphine and dopamine levels (2.51 +/- 0.76 ng/g for tyrosine and 2.39 +/- 0.64 ng/g for tyramine compared to approximately 1.0 ng/g morphine wet weight). Incubation with quinidine and/or AMPT diminished ganglionic morphine and dopamine synthesis at various steps in the synthesis process. We also demonstrated that CYP2D6 mediates the tyramine to dopamine step in this process, as did tyrosine hydroxylase in the step from tyrosine to L-DOPA. Furthermore, via RT-PCR, we identified a cDNA fragment of the CYP2D6 enzyme in the ganglia, which exhibits 94% sequence identity with its human counterpart. Evidence that tyrosine and tyramine were, in part, being converted to dopamine then morphine, and that this process can be inhibited by altering either or both CYP2D6 or tyrosine hydroxylase, is also provided. CONCLUSIONS: It appears that animals have the ability to make morphine. This process also appears to be dynamic in that the inhibition of one pathway allows the other to continue with morphine synthesis. Moreover, dopamine and morphine synthesis were coupled.

Animals↗

PubMed2005

[Chemical components of root exudates from allelopathic rice accession PI312777 seedlings].

In this study, allelopathic rice accession PI312777 seedlings were grown on a paddy soil under near natural condition, and their root exudates were collected by using circulation method, with the solution collected from no seedlings- planted soil as the control. The ether extracts of the root exudates and soil solution were detected by GC-MS, and identified with the mass spectral database of NIST and WILEY Library. The results showed that there were 36 compounds in the rice root exudates, including 9 terpenoids (peak area 10.97%), 8 phenols or quinones (5.87%), 6 esters (10.68%), 3 aldehydes or ketones (1.44%), 4 heterocycles (68.04%), 2 alcohols (1.23%), 2 ethers (0.57%), and 2 others (1.20%). A distinctly similar structure was observed among the terpenoids and among the phenols or quinones. In the soil solution, 39 compounds were detected, and 7 of them were the same of the root exudates. The difference of the compounds in rice root exudates and soil solution, and the possible allelopathic mechanisms of these compounds were discussed in this paper.

Heterocyclic Compounds↗

PubMed2004

[Evaluation efficiency of different bioassay methods on allelopathic potential of Oryza sativa].

In this paper, three bioassay methods, i.e., relay seeding in agar (RSA), relay seeding in silica (RSS) and seeding in rice root-exudation (SRE), were used to test the allelopathic potential of 8 rice cultivars on the target weed barnyardgrass (Echinochloa crusgalli). The results indicated that RSA was the ideal method for the bioassay, showing the highest efficiency in the evaluation of allelopathic potential. RSS and SRE had a lower efficiency than RSA, but these two methods showed the same tendency in evaluating the allelopathic potential of rice. RSA, the considered best bioassay method in this experiment, was used for 57 allelopathic rice germplasm screening, and 5 of them, i.e., Iguape Cateto, PI312777, Azucena, Taichung Native 1 and IAC25 performed the strongest allelopathic potential in the suppression on barnyardgrass.

Echinochloa↗

PubMed2002

[Genetic ecology of rice allelopathy on receiver plant].

In this study, 5 parental rice lines with different allelopathic potential were employed in partial diallel cross (4 x 5) to get 10 groups of F1 seeds. After testing the inhibitory effects of 5 parents and 10 F1s under different environment at different leaf stage on the shoot length of receiver plant lettuce(Lactuca sativa L.), dynamic genetics of rice allelopathy and its genotype x environment effects were analyzed by using additive-dominant developmental genetic models. The results showed that additive and dominant effect genes expressed alternatively during 3-leaf stage to 8-leaf stage in rice seedling. As additive effect genes were pronounced at 7-leaf stage, dominant effect genes appeared to play the most important role at 3-leaf stage and 6-leaf stage but the two effect genes were equally important at 5-leaf stage and 8-leaf stage. Heritabilities analysis indicated that the general heritability in the narrow sense(HN2) was significant at 5-, 7- and 8-leaf stage, and decreased with increasing leaf stage. Rice allelopathy was significantly affected by genotype x environment (GE) interaction, suggesting that the environment of allelopathic rice development must be controlled for practical use.

Ecology↗