Cannabinoid receptors are widely distributed in the nuclei of the extrapyramidal motor and mesolimbic reward systems; their exact functions are, however, not known. The aim of the present study was to characterize the effects of cannabinoids on the electrically evoked release of endogenous dopamine in the corpus striatum and the nucleus accumbens. In rat brain slices dopamine release elicited by single electrical pulses was determined by fast cyclic voltammetry. Dopamine release was markedly inhibited by the OP 2 opioid receptor agonist U-50488 and the D 2 /D 3 dopamine receptor agonist quinpirole, indicating that our method is suitable for studying presynaptic modulation of dopamine release. In contrast, the CB 1 /CB 2 cannabinoid receptor agonists WIN55212-2 (10 Ϫ6 M) and CP55940 (10 Ϫ6 -10 Ϫ5 M) and the CB 1 cannabinoid receptor antagonist SR141716A (10 Ϫ6 M) had no effect on the electrically evoked dopamine release in the corpus striatum and the nucleus accumbens. The lack of a presynaptic effect on terminals of nigrostriatal and mesolimbic dopaminergic neurons is in accord with the anatomical distribution of cannabinoid receptors: The perikarya of these neurons in the substantia nigra and the ventral tegmental area do not synthesize mRNA, and hence protein, for CB 1 and CB 2 cannabinoid receptors. It is therefore unlikely that presynaptic modulation of dopamine release in the corpus striatum and the nucleus accumbens plays a role in the extrapyramidal motor and rewarding effects of cannabinoids. Key Words: Cannabinoid receptor-Corpus striatumDopamine release-Nucleus accumbens-Presynaptic receptor-Voltammetry. J. Neurochem. 73, 1084Neurochem. 73, -1089Neurochem. 73, (1999.The primary molecular targets of the active components of marijuana and hashish are the cannabinoid receptors. Two G protein-coupled receptors have been identified, the CB 1 and CB 2 cannabinoid receptors; the CB 1 receptor is preferentially located on neurons, whereas the CB 2 receptor occurs mainly on peripheral nonneuronal cells (for review, see Howlett, 1995;Compton et al., 1996;Pertwee, 1997).The distribution of cannabinoid receptors in the CNS is well characterized (Herkenham et al., 1991;Jansen et al., 1992;Mailleux and Vanderhaeghen, 1992;Romero et al., 1997;Tsou et al., 1998). Moderate to high concentrations were observed in practically all regions belonging to the extrapyramidal motor system, e.g., corpus striatum, substantia nigra, globus pallidus, entopeduncular nucleus, and subthalamic nucleus, and the mesolimbic reward system, e.g., nucleus accumbens and ventral tegmental area. Accordingly, cannabinoids can markedly affect the function of these systems, producing catalepsy and rewarding effects (Howlett, 1995;Compton et al., 1996;Tanda et al., 1997;Martellotta et al., 1998). The exact mechanisms of these effects-how functions of identified neurons of the extrapyramidal motor and mesolimbic reward systems are influenced-are not known.It was recently reported that cannabinoids inhibit the electrically evoked releas...
For about a decade, superresolution fluorescence microscopy has been advancing steadily, maturing from the proof-of-principle stage to routine application. Of the various techniques, STED (stimulated emission depletion) microscopy was the first to break the diffraction barrier. Today, it is a prominent and versatile form of superresolution light microscopy. STED microscopy has shed a sharper light on numerous topics in cell biology, but also in material sciences. Both disciplines extend into the nanometer range, making detailed studies of structural and functional relationships difficult or even impossible to achieve using diffraction-limited microscopy. With recent advancements like spectral multiplexing or live-cell imaging, STED microscopy makes nanoscale materials and components of the cell accessible for fluorescence-based investigations. With multicolor superresolution imaging, even the interactions between biological and engineered nanostructures can be studied in detail. This review gives an introduction into the working principle of STED microscopy, provides a detailed overview of recent advancements and new techniques implemented for use with STED microscopy and shows how these have been applied in the life sciences and nanotechnologies.
Localization and intracellular migration of 32 and 83 nm SiO2 nanoparticles in relation to the nucleus was evaluated in vitro on undifferentiated human colon carcinoma (Caco-2) cells. The fluorescence dye Atto647N was incorporated into the particles, which enabled detection by high resolution, nondiffraction limited stimulated emission depletion (STED) microscopy. The distribution and agglomeration of nanoparticles was measured with STED microscopy after 5, 24, 48, and 72 h. Analyses revealed that only 32 nm silica particles penetrated into the nucleus of Caco-2 cells upon exposure for 24 h. Here, they formed agglomerates up to 300 nm after 72 h of incubation. Quantitative evaluation of the migration of 32 nm compared to 83 nm particles demonstrated that 32 nm particles obviously migrated faster into and through the cell in the beginning (5 h time point). The presence and agglomeration inside the cells and the penetration into the nucleus were considered to potentially activate cytotoxic responses. Therefore, the cytotoxic (WST-1 assay) and genotoxic (comet assay) effects of the silica nanoparticles were evaluated. Even though 32 nm silica particles are penetrating into the nucleus, neither cytotoxic nor genotoxic effects were detected for either particle size.
Transparency and bendability are some of the most attractive unique selling points for organic light-emitting diode (OLED) lighting, enabling a variety of new application possibilities for industrial and private end-users. The roll-to-roll (R2R) OLED fabrication based on thermal evaporation offers a fast, continuous-running solution for producing flexible OLEDs at a lower cost. In this work, R2R fabricated large-area highly transparent thermal co-evaporated Ca:Ag (2:1 vol.%) top-electrode with mean transmittance of 64% over the visible range and a corresponding sheet resistance of as low as 21 Ω sq−1 was achieved. By increasing the film thickness to 24 nm, the sheet resistance can be further reduced to 12 Ω sq−1, albeit with a lower mean transmittance of 58%. The Ca:Ag electrode demonstrates a high mechanical durability through 1000 bending cycles, which is highly desirable as a characteristic for flexible electronics, as well as for the R2R fabrication. Finally, the stability of the Ca:Ag electrode in vacuum and ambient was studied as well.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.