Jejuketomycins A and B, polyketide glycosides with cancer cell migration inhibitory activity from Streptomyces sp. KCB15JA151.

Two new polyketide glycosides jejuketomycins A (1) and B (2), were isolated from a culture of Streptomyces sp. KCB15JA151. Their chemical structures including the absolute configurations were determined by detailed analyses of the NMR and HRMS data and ECD calculations and spectral data. Compounds 1 and 2 possess an unusual 6/6/8 tricyclic ring system. Biological evaluation with the wound healing assay and time-lapse cell tracking analysis revealed that compounds 1 and 2 have significant inhibitory activities against cancer cell migration with low cytotoxicity.

Dopamine D2-Subtype Receptors Outside the Blood-Brain Barrier Mediate Enhancement of Mesolimbic Dopamine Release and Conditioned Place Preference by Intravenous Dopamine.

Dopamine (DA) is a cell-signaling molecule that does not readily cross the blood-brain barrier. Despite this, peripherally administered DA enhances DA levels in the nucleus accumbens and alters DA-related behaviors. This study was designed to investigate whether DA subtype-2 receptors are involved in the enhancement of nucleus accumbens (NAc) DA levels elicited by intravenous DA administration. This was accomplished by using microdialysis in the NAc and extracellular single unit recordings of putative DA neurons in the ventral tegmental area (VTA). Additionally, the reinforcing properties of intravenous DA were investigated using a place conditioning paradigm and the effects of intravenous DA on ultrasonic vocalizations were assessed. Following administration of intravenous dopamine, the firing rate of putative DA neurons in the VTA displayed a biphasic response and DA levels in the nucleus accumbens were enhanced. Pretreatment with domperidone, a peripheral-only DA D2 receptor (D2R) antagonist, reduced intravenous DA mediated increases in VTA DA neuron activity and NAc DA levels. Pretreatment with phentolamine, a peripheral α-adrenergic receptor antagonist, did not alter the effects of IV DA on mesolimbic DA neurotransmission. These results provide evidence for peripheral D2R mediation of the effects of intravenous DA on mesolimbic DA signaling.

The peripheral dopamine 2 receptor antagonist domperidone attenuates ethanol enhancement of dopamine levels in the nucleus accumbens.

BACKGROUND: Dopamine neuron firing in the ventral tegmental area (VTA) and dopamine release in the nucleus accumbens have been implicated in reward learning. Ethanol is known to increase both dopamine neuron firing in the VTA and dopamine levels in the nucleus accumbens. Despite this, some discrepancies exist between the dose of ethanol required to enhance firing in vivo and ex vivo. In the present study we investigated the effects of peripheral dopamine 2 subtype receptor antagonism on ethanol's effects on dopamine neurotransmission. METHODS: Plasma catecholamine levels were assessed following ethanol administration across four different doses of EtOH. Microdialysis and voltammetry were used to assess the effects of domperidone pretreatment on ethanol-mediated increases in dopamine release in the nucleus accumbens. A place conditioning paradigm was used to assess conditioned preference for ethanol and whether domperidone pretreatment altered this preference. Open-field and loss-of-righting reflex paradigms were used to assess the effects of domperidone on ethanol-induced sedation. A rotarod apparatus was used to assess the effects of domperidone on ethanol-induced motor impairment. RESULTS: Domperidone attenuated ethanol's enhancement of mesolimbic dopamine release under non-physiological conditions at intermediate (1.0 and 2.0 g/kg) doses of ethanol. Domperidone also decreased EtOH-induced sedation at 2.0 g/kg. Domperidone did not alter ethanol conditioned place preference nor did it affect ethanol-induced motor impairment. CONCLUSIONS: These results show that peripheral dopamine 2 receptors mediate some of the effects of ethanol on nonphysiological dopamine neurotransmission, although these effects are not related to the rewarding properties of ethanol.

Engineered Escherichia coli strains as platforms for biological production of isoprene.

Volatile compounds can be produced by fermentation from genetically engineered microorganisms. Escherichia coli strains are mainly used for isoprene production owing to their higher titers; however, this has thus far been confined to only strains BL21, BL21 (DE3), Rosetta, and BW25113. Here, we tested four groups of E. coli strains for improved isoprene production, including K-12 (DH5α, BW25113, W3110, MG1655, XL1-Blue, and JM109), B [Rosetta (DE3), BL21, and BL21 (DE3)], Crooks C, and Waksman W strains. The isoprene productivity of BL21 and MG1655 was remarkably higher than that of the others in 5-L fermentation, and scale-up fermentation (300 L) of BL21 was successfully performed. This system shows potential for biobased production of fuel and volatile compounds in industrial applications.

Involvement of the Cuneate Nucleus in the Acupuncture Inhibition of Drug-Seeking Behaviors.

Our previous studies have shown that acupuncture suppresses addictive behaviors induced by drugs of abuse, including cocaine, morphine and ethanol, by modulating GABA neurons in the ventral tegmental area (VTA) and dopamine (DA) release in the nucleus accumbens (NAc). The mechanisms by which the peripheral signals generated by acupoint stimulation are transmitted to brain reward systems are largely unexplored. The present study aims to investigate the role of spinal dorsal column (DC) somatosensory pathways in the acupuncture inhibition of drug addictive behaviors. Thus, we tested whether acupuncture at Shenmen (HT7) points reduces drug-seeking behaviors in rats self-administering morphine or ethanol and whether such effects are inhibited by the disruption of the cuneate nucleus (CN). The stimulation of HT7 suppressed morphine and ethanol self-administration, which were completely abolished by surgical lesioning of the CN. In in vivo extracellular recordings, single-unit activity of the CN was evoked during acupuncture stimulation. The results suggest that acupuncture suppresses morphine- and ethanol-seeking behaviors through the modulation of the CN, second-order neurons of the DC somatosensory pathway.

Development of novel on-line capillary gas chromatography-based analysis method for volatile organic compounds produced by aerobic fermentation.

Many volatile compounds, such as isoprene, a precursor used in the synthesis of natural rubber, have been produced through fermentation using genetically engineered microorganisms. Despite this biotechnological success, measuring the concentrations of volatile compounds during fermentation is difficult because of their high volatility. In current systems, off-line analytical methods usually lead to product loss, whereas on-line methods raise the production cost due to the requirement of complex devices. Here, we developed a novel on-line gas chromatography (GC)-based system for analyzing the concentration of isoprene with the aim to minimize the cost and requirement for devices as compared to current strategies. In this system, a programmable logic controller is used to combine conventional GC with a syringe pump module (SPM) directly connected to the exhaust pipe of the fermentor, and isoprene-containing samples are continuously pumped from the SPM into the GC using an air cylinder recycle stream. We showed that this novel system enables isoprene analysis during fermentation with convenient equipment and without the requirement of an expensive desorption tube. Furthermore, this system may be extended to the detection of other volatile organic compounds in fermentation or chemical processes.

Acupuncture reduces relapse to cocaine-seeking behavior via activation of GABA neurons in the ventral tegmental area.

There is growing public interest in alternative approaches to addiction treatment and scientific interest in elucidating the neurobiological underpinnings of acupuncture. Our previous studies showed that acupuncture at a specific Shenmen (HT7) points reduced dopamine (DA) release in the nucleus accumbens (NAc) induced by drugs of abuse. The present study was carried out to evaluate the effects of HT7 acupuncture on γ-aminobutyric acid (GABA) neuronal activity in the ventral tegmental area (VTA) and the reinstatement of cocaine-seeking behavior. Using microdialysis and in vivo single-unit electrophysiology, we evaluated the effects of HT7 acupuncture on VTA GABA and NAc DA release and VTA GABA neuronal activity in rats. Using a within-session reinstatement paradigm in rats self-administering cocaine, we evaluated the effects of HT7 stimulation on cocaine-primed reinstatement. Acupuncture at HT7 significantly reduced cocaine suppression of GABA release and GABA neuron firing rates in the VTA. HT7 acupuncture attenuated cocaine-primed reinstatement, which was blocked by VTA infusions of the selective GABAB receptor antagonist 2-hydroxysaclofen. HT7 stimulation significantly decreased acute cocaine-induced DA release in the NAc, which was also blocked by 2-hydroxysaclofen. HT7 acupuncture also attenuated cocaine-induced sensitization of extracellular DA levels in the NAc. Moreover, HT7 acupuncture reduced both locomotor activity and neuronal activation in the NAc induced by acute cocaine in a needle-penetration depth-dependent fashion. These results suggest that acupuncture may suppress cocaine-induced DA release in the NAc and cocaine-seeking behavior through activation of VTA GABA neurons. Acupuncture may be an effective therapy to reduce cocaine relapse by enhancing GABAergic inhibition in the VTA.

Enhancement of L-Threonine Production by Controlling Sequential Carbon-Nitrogen Ratios during Fermentation.

Controlling the residual glucose concentration is important for improving productivity in L-threonine fermentation. In this study, we developed a procedure to automatically control the feeding quantity of glucose solution as a function of ammonia-water consumption rate. The feeding ratio (RC/N) of glucose and ammonia water was predetermined via a stoichiometric approach, on the basis of glucose-ammonia water consumption rates. In a 5-L fermenter, 102 g/l L-threonine was obtained using our glucose-ammonia water combined feeding strategy, which was then successfully applied in a 500-L fermenter (89 g/l). Therefore, we conclude that an automatic combination feeding strategy is suitable for improving L-threonine production.

Silica stationary phase-based on-line sample enrichment coupled with LC-MS/MS for the quantification of dopamine, serotonin and their metabolites in rat brain microdialysates.

Accurate measurement of trace levels of endogenous compounds remains challenging despite advancements in analytical technologies. In particular, monoamine neurotransmitters such as dopamine (DA) and serotonin (5-HT) are polar compounds with low molecular weights, which complicates the optimization of retention and detection on liquid chromatography-mass spectrometry (LC-MS). Microdialysis is an important sampling technique to collect extracellular fluid from the brain of living animals. However, the very low basal concentrations of the neurotransmitters, small sample volume (maximum 30 µL) and the absence of matrix-matching calibrators are limitations of a microdialysate as an analytical sample. In the present study, an LC-MS/MS method was developed and fully validated for the quantification of DA, 5-HT and their main metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), in microdialysates from the rat nucleus accumbens shell. To improve the method sensitivity and accuracy, on-line sample enrichment using silica stationary phase was employed, before which any other sample pretreatment was not performed. The validation results proved the method to be selective, sensitive, accurate and precise, with acceptable linearity within calibration ranges. The lower limits of quantification were 0.025, 0.1, 0.5, 25 and 2.5 ng/mL for 5-HT, DA, 5-HIAA, HVA and DOPAC, respectively. This is a powerful analytical method to determine endogenous concentrations of those compounds in microdialysates from the rat nucleus accumbens and will be very useful to further study on the pathophysiological functions of monoamine neurotramsmitters in vivo.