Aging effects on the BDNF mRNA and TrkB mRNA expression of the hippocampus in different durations of stress.

Brain-derived neurotrophins factor (BDNF) belongs to the neurotrophins family which acts on neuronal survival and growth and has been associated with cognition process. TrkB is the primary signal transduction receptor for BDNF. In the present study, hippocampal BDNF and TrkB mRNA were detected by RT-PCR in 2- and 22-month rats, respectively, which were exposed to different durations of mild stress protocol of 8-day, 21-day and 28-day chronic unpredictable mild stress (CUMS). Observation of exploratory behavior in an open field (OF) test indicated stress levels and changes of spontaneous activity. We demonstrated that CUMS induced decrease of BDNF mRNA in two aged groups, but the increase change of TrkB mRNA compared with those of the control groups. Moreover, the changes of BDNF mRNA and TrkB mRNA measured in both the 21-day and 28-day stress groups represent obvious decrease than those of the 8-day stress groups, and the expression examined in young groups appeared to be higher than those of the aged group, especially in the 28-day stress groups. Results of OF test showed that explicit behaviors in two age groups decreased gradually with the process of stress revealing a depressive state under the stress condition. Meanwhile, the behaviors of young rats seemed to be more active than those of the aged rats, exhibiting weak adaptation to the stress. The study suggested that stress paradigm and aging certainly had effect on the regulation of BDNF mRNA and TrkB mRNA which might be related to damage and protection function of the hippocampus.

Polymer-Based Device Fabrication and Applications Using Direct Laser Writing Technology.

Polymer materials exhibit unique properties in the fabrication of optical waveguide devices, electromagnetic devices, and bio-devices. Direct laser writing (DLW) technology is widely used for micro-structure fabrication due to its high processing precision, low cost, and no need for mask exposure. This paper reviews the latest research progresses of polymer-based micro/nano-devices fabricated using the DLW technique as well as their applications. In order to realize various device structures and functions, different manufacture parameters of DLW systems are adopted, which are also investigated in this work. The flexible use of the DLW process in various polymer-based microstructures, including optical, electronic, magnetic, and biomedical devices are reviewed together with their applications. In addition, polymer materials which are developed with unique properties for the use of DLW technology are also discussed.

Recent Progress of Imprinted Polymer Photonic Waveguide Devices and Applications.

Polymers are promising materials for fabricating photonic integrated waveguide devices. Versatile functional devices can be manufactured using a simple process, with low cost and potential mass-manufacturing. This paper reviews the recent progress of polymer photonic integrated devices fabricated using the UV imprinting technique. The passive polymer waveguide devices for wavelength filtering, power splitting, and light collecting, and the active polymer waveguide devices based on the thermal-optic tuning effect, are introduced. Then, the electro-optic (EO) modulators, by virtue of the high EO coefficient of polymers, are described. Finally, the photonic biosensors, which are based on low-cost and biocompatible polymer platforms, are presented.