Near-infrared light induces neurogenesis and modulates anxiety-like behavior

Stem Cell Res Ther. 2024 Dec 20;15(1):494. doi: 10.1186/s13287-024-04114-3.

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Anxiety; Astrocytes; Calcium activity; NIR Light; Neural stem cells.

MeSH terms

  • Animals
  • Anxiety* / therapy
  • Astrocytes / metabolism
  • Behavior, Animal / radiation effects
  • Cell Differentiation
  • Cell Proliferation* / radiation effects
  • Hippocampus* / metabolism
  • Hippocampus* / radiation effects
  • Infrared Rays*
  • Male
  • Mice
  • Mice, Inbred C57BL*
  • Neural Stem Cells* / cytology
  • Neural Stem Cells* / metabolism
  • Neurogenesis* / radiation effects