º£½ÇÆƽâ°æ

GABA B receptor (GABA B R) activation is known to alleviate pain by reducing neuronal excitability, primarily through inhibition of high voltage©\activated (HVA) calcium (Ca V 2.2) channels and potentiating G protein¨Ccoupled inwardly rectifying potassium (GIRK) channels. Although the analgesic properties of small molecules and peptides have been primarily tested on isolated murine dorsal root ganglion (DRG) neurons, emerging strategies to develop, study, and characterise human pluripotent stem cell (hPSC)©\derived sensory neurons present a promising alternative. In this study, hPSCs were efficiently differentiated into peripheral DRG©\induced sensory neurons (iSNs) using a combined chemical and transcription factor©\driven approach via a neural crest cell intermediate. Molecular characterisation and transcriptomic analysis confirmed the expression of key DRG markers such as BRN3A, ISLET1, and PRPH, in addition to GABA B R and ion channels including Ca V 2.2 and GIRK1 in iSNs. Functional characterisation of GABA B R was conducted using whole©\cell patch clamp electrophysiology, assessing neuronal excitability under current©\clamp conditions in the absence and presence of GABA B R agonists baclofen and ¦Á©\conotoxin Vc1.1. Both baclofen (100?¦ÌM) and Vc1.1 (1?¦ÌM) significantly reduced membrane excitability by hyperpolarising the resting membrane potential and increasing the rheobase for action potential firing. In voltage©\clamp mode, baclofen and Vc1.1 inhibited HVA Ca 2+ channel currents, which were attenuated by the selective GABA B R antagonist CGP 55845. However, modulation of GIRK channels by GABA B Rs was not observed in the presence of baclofen or Vc1.1, suggesting that functional GIRK1/2 channels were not coupled to GABA B Rs in hPSC©\derived iSNs. This study is the first to report GABA B R modulation of membrane excitability in iSNs by baclofen and Vc1.1, highlighting their potential as a future model for studying analgesic compounds.

The hippocampus is associated with mood disorders, and the activation of quiescent neurogenesis has been linked to anxiolytic effects. Near-infrared (NIR) light has shown potential to improve learning and memory in human and animal models. Despite the vast amount of information regarding the effect of visible light, there is a significant gap in our understanding regarding the response of neural stem cells (NSCs) to NIR stimulation, particularly in anxiety-like behavior. The present study aimed to develop a new optical manipulation approach to stimulate hippocampal neurogenesis and understand the mechanisms underlying its anxiolytic effects. We used 940 nm NIR (40 Hz) light exposure to stimulate hippocampal stem cells in C57BL/6 mice. The enhanced proliferation and astrocyte differentiation of NIR-treated NSCs were assessed using 5-ethynyl-2¡¯-deoxyuridine (EdU) incorporation and immunofluorescence assays. Additionally, we evaluated calcium activity of NIR light-treated astrocytes using GCaMP6f recording through fluorescence fiber photometry. The effects of NIR illumination of the hippocampus on anxiety-like behaviors were evaluated using elevated plus maze and open-field test. NIR light effectively promoted NSC proliferation and astrocyte differentiation via the OPN4 photoreceptor. Furthermore, NIR stimulation significantly enhanced neurogenesis and calcium-dependent astrocytic activity. Moreover, activating hippocampal astrocytes with 40-Hz NIR light substantially improved anxiety-like behaviors in mice. We found that flickering NIR (940?nm/40Hz) light illumination improved neurogenesis in the hippocampus with anxiolytic effects. This innovative approach holds promise as a novel preventive treatment for depression. The online version contains supplementary material available at 10.1186/s13287-024-04114-3.