Intermittent long-wavelength red light increases the period of daily locomotor activity in mice

Abstract

BackgroundWe observed that a dim, red light-emitting diode (LED) triggered by activity increased the circadian periods of lab mice compared to constant darkness. It is known that the circadian period of rats increases when vigorous wheel-running triggers full-spectrum lighting; however, spectral sensitivity of photoreceptors in mice suggests little or no response to red light. Thus, we decided to test the following hypotheses: dim red light illumination triggered by activity (LEDfb) increases the circadian period of mice compared to constant dark (DD); covering the LED prevents the effect on period; and DBA2/J mice have a different response to LEDfb than C57BL6/J mice.MethodsThe irradiance spectra of the LEDs were determined by spectrophotometer. Locomotor activity of C57BL/6J and DBA/2J mice was monitored by passive-infrared sensors and circadian period was calculated from the last 10 days under each light condition. For constant dark (DD), LEDs were switched off. For LED feedback (LEDfb), the red LED came on when the mouse was active and switched off seconds after activity stopped. For taped LED the red LED was switched on but covered with black tape. Single and multifactorial ANOVAs and post-hoc t-tests were done.ResultsThe circadian period of mice was longer under LEDfb than under DD. Blocking the light eliminated the effect. There was no difference in period change in response to LEDfb between C57BL/6 and DBA/2 mice.ConclusionAn increase in mouse circadian period due to dim far-red light (1 lux at 652 nm) exposure was unexpected. Since blocking the light stopped the response, sound from the sensor's electronics was not the impetus of the response. The results suggest that red light as background illumination should be avoided, and indicator diodes on passive infrared motion sensors should be switched off.

Melanopsin-expressing retinal ganglion cell loss and behavioral analysis in the Thy1-CFP-DBA/2J mouse model of glaucoma

“…It is plausible that highly active locomotor activities are not the result of loss of conventional RGCs or mRGCs, but are caused by other factors such as genetic mutations in this species [26,27, 50,51]. The DBA/2J mouse is a popular model for anxiety-and locomotion-related behaviors [52,53], but this animal exhibits normal circadian rhythm [54]. In agreement with this finding, our results show that Brn-3b-negative mRGCs, which we suspect are M1-type mRGCs, had less injury than Brn-3b-positive mRGCs (M2–5) (Figure 7).…”

A guideline for analyzing circadian wheel-running behavior in rodents under different lighting conditions

“…Djungarian hamsters, for example, have a very high photosensitivity to red light (10). A recent publication suggests not using dim red light because it can increase the circadian period in mice compared to constant darkness (11). Therefore, it is recommended to use complete darkness protocols and to handle the animals using night vision goggles equipped with an infrared beam.…”

MAGE-D1 Regulates Expression of Depression-Like Behavior through Serotonin Transporter Ubiquitylation

“…The circadian rhythm activity test was performed according to the method outlined in previous reports (Hofstetter et al, 2005;Kasahara et al, 2006) with a minor modification. Locomotor activity was measured using an infrared detector (Brain Science Idea) in each transparent cage (32 ϫ 22 ϫ 15 cm high).…”