Opposite modulatory roles for adenosine A1 and A2A receptors on glutamate and dopamine release in the shell of the nucleus accumbens. Effects of chronic caffeine exposure

Previous studies have demonstrated opposing roles for adenosine A1 and A2A receptors in the modulation of extracellular levels of glutamate and dopamine in the striatum. In the present study, acute systemic administration of motor-activating doses of the A2A receptor antagonist MSX-3 significantly decreased extracellular levels of dopamine and glutamate in the shell of the rat nucleus accumbens (NAc) and counteracted both dopamine and glutamate release induced by systemic administration of motor-activating doses of either the A1 receptor antagonist CPT or caffeine. Furthermore, exposure to caffeine in the drinking water (1 mg/mL, 14 days) resulted in tolerance to the effects of systemic injection of CPT or caffeine, but not MSX-3, on extracellular levels of dopamine and glutamate in the NAc shell. The present results show: first, the existence of opposite tonic effects of adenosine on extracellular levels of dopamine and glutamate in the shell of the NAc mediated by A1 and A2A receptors; second, that complete tolerance to caffeine's dopamine- and glutamate-releasing effects which develops after chronic caffeine exposure is attributable to an A1 receptor-mediated mechanism. Development of tolerance to the dopamine-releasing effects of caffeine in the shell of the NAc may explain its weak addictive properties and atypical psychostimulant profile.     

Prostate Sphere-forming Stem Cells Are Derived from the P63-expressing Basal Compartment

Prostate stem cells (P-SCs) are capable of giving rise to all three lineages of prostate epithelial cells, including basal, luminal, and neuroendocrine cells. Multiple methods have been used to identify P-SCs in adult prostates. These include in vivo renal capsule implantation of a single epithelial cell with urogenital mesenchymal cells, in vitro prostasphere and organoid cultures, and lineage tracing with castration-resistant Nkx3.1 expression (CARN), in conjunction with expression of cell type-specific markers. Both organoid culture and CARN tracing show the existence of P-SCs in the luminal compartment. Although prostasphere cells predominantly express basal cell-specific cytokeratin and P63, the lineage of prostasphere-forming cells in the P-SC hierarchy remains to be determined. Using lineage tracing with P63^CreERT2, we show here that the sphere-forming P-SCs are P63-expressing cells and reside in the basal compartment. Therefore we designate them as basal P-SCs (P-bSCs). P-bSCs are capable of differentiating into AR⁺ and CK18⁺ organoid cells, but organoid cells cannot form spheres. We also report that prostaspheres contain quiescent stem cells. Therefore, the results show that P-bSCs represent stem cells that are early in the hierarchy of overall prostate tissue stem cells. Understanding the contribution of the two types of P-SCs to prostate development and prostate cancer stem cells and how to manipulate them may open new avenues for control of prostate cancer progression and relapse.     

高山被孢霉产花生四烯酸及其遗传改造的研究进展

花生四烯酸作为一种重要的多价不饱和脂肪酸,因其具有多种生理功能而被认为是潜在的食品添加剂和药物。近年来,利用高山被孢霉合成花生四烯酸已成为研究热点。前期相关研究主要集中在菌种选育及发酵调控方面。随着研究的不断深入,关于高山被孢霉合成花生四烯酸的代谢途径的研究取得了较大进展。以下简要概述前期工作进展,着重论述花生四烯酸合成途径的关键酶及其高山被孢霉的遗传改造的研究情况,包括生物合成花生四烯酸代谢途径、关键酶及其应用、高山被孢霉的遗传操作系统的构建以及遗传改造的应用,并对其研究前景进行了展望。     

微透析技术在脑靶向中应用

微透析技术作为一门新兴的技术,近年来多用于靶向分布和体内代谢等方面,尤其是在药物的脑部研究方面,该技术显得尤为重要。如今,随着新型探针的不断出现,以及微量、快速、灵敏的分析检测手段的发展,微透析技术已日益成为药物脑部研究的重要工具。现通过检索近十年来的相关文献,对脑微透析技术的概况、原理、脑微透析探针以及其应用作一综述,希望能为从事该方面研究的药学工作者提供相关参考。     

Detection of hybridization between two loach species (<Emphasis Type="Italic">Paramisgurnus dabryanus</Emphasis> and <Emphasis Type="Italic">Misgurnus anguillicaudatus</Emphasis>) in wild populations

Artificial interspecific hybrids between large scale loach P. dabryanus and tetraploid pond loach M. anguillicaudatus (Cobitidae, Cypriniformes) are viable. To detect the occurrence of possible natural hybridization, genetic analyses by using microsatellite markers were performed for natural populations of large scale loach and pond loach, the reciprocal laboratory hybrids, and “supposed hybrids” with ambiguous morphology. The fertility of the artificial hybrids was also tested. At one diagnostic microsatellite (Mac50), one out of 20 “supposed hybrids” was identified to be F₁ hybrid between the two loach species because it had the same genotype as that of the laboratory hybrids. The triploid hybrids between the two species were confirmed to be female-sterile. The results show that rare hybridization has occurred between diploid large scale loach and tetraploid pond loach in nature although it may have little effect in genetic introgression. This study is helpful for fish conservation and encourages further investigation on natural hybridization and introgression of loaches.     

High glucose concentration induces endothelial cell proliferation by regulating cyclin‐D2‐related miR‐98

Cyclin D2 is involved in the pathology of vascular complications of type 2 diabetes mellitus (T2DM). This study investigated the role of cyclin‐D2‐regulated miRNAs in endothelial cell proliferation of T2DM. Results showed that higher glucose concentration (4.5 g/l) significantly promoted the proliferation of rat aortic endothelial cells (RAOECs), and significantly increased the expression of cyclin D2 and phosphorylation of retinoblastoma 1 (p‐RB1) in RAOECs compared with those under low glucose concentration. The cyclin D2‐3′ untranslated region is targeted by miR‐98, as demonstrated by miRNA analysis software. Western blot also confirmed that cyclin D2 and p‐RB1 expression was regulated by miR‐98. The results indicated that miR‐98 treatment can induce RAOEC apoptosis. The suppression of RAOEC growth by miR‐98 might be related to regulation of Bcl‐2, Bax and Caspase 9 expression. Furthermore, the expression levels of miR‐98 decreased in 4.5 g/l glucose‐treated cells compared with those treated by low glucose concentration. Similarly, the expression of miR‐98 significantly decreased in aortas of established streptozotocin (STZ)‐induced diabetic rat model compared with that in control rats; but cyclin D2 and p‐RB1 levels remarkably increased in aortas of STZ‐induced diabetic rats compared with those in healthy control rats. In conclusion, this study demonstrated that high glucose concentration induces cyclin D2 up‐regulation and miR‐98 down‐regulation in the RAOECs. By regulating cyclin D2, miR‐98 can inhibit human endothelial cell growth, thereby providing novel therapeutic targets for vascular complication of T2DM.     

The miR-302c/transforming growth factor-β receptor type-2 axis modulates interleukin-1β-induced degenerative changes in osteoarthritic chondrocytes

Chondrocyte production of catabolic and inflammatory mediators participating in extracellular matrix degradation has been regarded as a central event in osteoarthritis (OA) development. During OA pathogenesis, interleukin-1β (IL-1β) decreases the mRNA expression and protein levels of transforming growth factor-β receptor type-2 (TGFBR2), thus disrupting transforming growth factor-β signaling and promoting OA development. In the present study, we attempted to identify the differentially expressed genes in OA chondrocytes upon IL-1β treatment, investigate their specific roles in OA development, and reveal the underlying mechanism. As shown by online data analysis and experimental results, TGFBR2 expression was significantly downregulated in IL-1β-treated human primary OA chondrocytes. IL-1β treatment induced degenerative changes in OA chondrocytes, as manifested by increased matrix metalloproteinase 13 and a disintegrin and metalloproteinase with thrombospondin motifs 5 proteins, decreased Aggrecan and Collagen II proteins, and suppressed OA chondrocyte proliferation. These degenerative changes were significantly reversed by TGFBR2 overexpression. miR-302c expression was markedly induced by IL-1β treatment in OA chondrocytes. miR-302c suppressed the expression of TGFBR2 via direct binding to its 3′- untranslated region. Similar to TGFBR2 overexpression, miR-302c inhibition significantly improved IL-1β-induced degenerative changes in OA chondrocytes. Conversely, TGFBR2 silencing enhanced IL-1β-induced degenerative changes and significantly reversed the effects of miR-302c inhibition in response to IL-1β treatment. In conclusion, the miR-302c/TGFBR2 axis could modulate IL-1β-induced degenerative changes in OA chondrocytes and might become a novel target for OA treatment.Electronic supplementary materialThe online version of this article (10.1007/s12079-020-00591-2) contains supplementary material, which is available to authorized users.     

Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies.However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China. We conducted a spatial phylogenetic analysis of the Chinese angiosperm flora at the generic level to identify centers of neo-and pale...     

The use of intensity‐based Doppler variance method for single vessel response to functional neurovascular activation

This study presents 1 use of optical coherence tomography (OCT) angiography technique to examine neurovascular coupling effect. Repeated B‐scans OCT recording is performed on the rat somatosensory cortex with cranial window preparation while its contralateral forepaw is electrically stimulated to activate the neurons in rest. We use an intensity‐based Doppler variance (IBDV) algorithm mapped cerebral blood vessels in the cortex, and the temporal alteration in blood perfusion during neurovascular activation is analyzed using the proposed IBDV quantitative parameters. By using principal component analysis‐based Fuzzy C Means clustering method, the stimulus‐evoked vasomotion patterns were classified into 3 categories. We found that the response time of small vessels (resting diameter 14.9 ±6.6 μm), middle vessels (resting diameter 21.1 ±7.9 μm) and large vessels (resting diameter 50.7 ±6.5 μm) to achieve 5% change of vascular dilation after stimulation was 1.5, 2 and 5.5 seconds, respectively. Approximately 5% peak change of relative blood flow (RBF) in both small and middle vessels was observed. The large vessels react slowly and their responses nearly 4 seconds delayed, but no significant change in RBF of the large vessels was seen.