Strain specific behavioral and physiological responses to constant light in male CBA/J and CBA/CaJ mice

Abstract

Objective: Being visually impaired increases the likelihood of sleep disorders and altered behavior. This study investigated physiological and behavioral differences in two similar mice substrains when exposed to constant light (LL) -CBA/J with retinal degeneration and CBA/CaJ mice (no retinal degeneration). Material and Methods: Male CBA/J and CBA/CaJ mice were placed into a 12:12 light:dark cycle or constant light (LL). Open field behavior, metabolic markers, and home-cage circadian activity were observed. Results: CBA/CaJ mice have greater circadian period lengthening, increased weight gain, reduced glucose, and increased novelty-induced locomotor activity in LL, compared to CBA/J mice. LL reduced thyroid hormone and insulin in both substrains. Discussion: While several baseline substrain differences were elucidated, CBA/CaJ mice were more effected by the exposure to LL than the blind CBA/J mice. These results illustrate that LL causes alterations in physiology and behavior and that circadian photoreceptivity might contribute to these effects.

Estradiol Regulates Circadian Responses to Acute and Constant Light Exposure in Female Mice

“…The length of the free-running period in LL is directly proportional to the light intensity and circadian photosensitivity of the organism. Both melanopsin knock-out (KO) mice (with reduced light cues to the SCN) and human and animal models experiencing blindness also exhibit shorter periods in lengthened light exposure (Ruby et al, 2002; Lockley et al, 2007; Deane et al, 2021). Another study also reported that the greater the degree of light intensity, the longer the circadian period (Steinlechner et al, 2002).…”

Effects of Blindness on Sleep/Wakefulness States in Mice

“…The CBA strain includes CBA/J mice with the rd1 mutation and sub-strains without the rd1 modification (such as CBA/N and CBA/CaJ). [15][16][17][18] Previous studies reported that CBA/J mice were less sensitive to light and showed reduced circadian photosensitivity. 15,18) However, the sleep/wakefulness states in CBA/J mice remain unclear.…”

“…[15][16][17][18] Previous studies reported that CBA/J mice were less sensitive to light and showed reduced circadian photosensitivity. 15,18) However, the sleep/wakefulness states in CBA/J mice remain unclear. Therefore, the effects of the rd1 mutation on the sleep/wake status were examined herein using mice with similar genetic backgrounds, namely, CBA/N and CBA/J mice.…”