Tackenberg, M. | bioRxiv Science

bioRxiv2026

A microstructural analysis of water intake patterns associated with light phase food and water restriction in male and female rats.

Water intake is influenced by both eating and circadian rhythms, and the available literature is mixed regarding which variable exerts greater control. Previous reports primarily focused on short term manipulations, however, one study using long term light phase food restriction found that water intake patterns primarily retained circadian characteristics in male rats. To further characterize this behavioral effect, water intake and lick microstructure was analyzed in male and female rats with food access restricted to the light phase. In addition, food and water intake and lick microstructure were analyzed when water access was restricted to the light phase. In support of the previous short term, but not long term, food manipulation studies, when food access was restricted to the light phase most water intake shifted to this time frame. This shift was medicated by increased lick burst number, suggesting altered satiety signaling underling this intake pattern. When water access was restricted to the light phase, food intake was equally distributed across the light and dark phases. There was no effect of sex on the patterns of intake during any test condition. These results further our understanding of the mechanisms underlying food and water-associated and circadian intake patterns by suggesting that altered satiety signaling underlies changes in water intake. Furthermore, these results show that the timing of food access has a greater effect on water intake patterns across the light-dark cycle than water access has on food intake patterns.

physiology↗

bioRxiv2020

Distinct components of photoperiodic light are differentially encoded by the mammalian circadian clock

Seasonal light cycles influence multiple physiological functions and are mediated through photoperiodic encoding by the circadian system. Despite our knowledge of the strong connection between seasonal light input and downstream circadian changes, less is known about the specific components of seasonal light cycles that are encoded and induce persistent changes in the circadian system. Using combinations of three T cycles (23, 24, 26 hr.) and two photoperiods per T cycle (Long and Short, with duty cycles scaled to each T cycle), we investigate after-effects of entrainment to these six light cycles. We measure locomotor behavior duration (), period ({tau}), and entrained phase angle ({Psi}) in vivo, and SCN phase distribution ({sigma}{phi}), {tau}, and {Psi} ex vivo in order to refine our understanding of critical light components for influencing particular circadian properties. We find that photoperiod and T cycle length both drive determination of in vivo {Psi} but differentially influence after-effects in and {tau}, with photoperiod driving changes in and photoperiod length and T cycle length combining to influence {tau}. Using skeleton photoperiods, we demonstrate that in vivo {Psi} is determined by both parametric and non-parametric components, while changes in are driven non-parametrically. Within the ex vivo SCN, we find that {Psi} and {sigma}{phi} of the PER2::LUCIFERASE rhythm follow closely with their likely behavioral counterparts ({Psi} and of the locomotor activity rhythm), while also confirming previous reports of {tau} after-effects of gene expression rhythms showing negative correlations with behavioral {tau} after-effects in response to T cycles. We demonstrate that within-SCN {sigma}{phi} changes, thought to underly changes in vivo, are induced primarily non-parametrically. Taken together, our results demonstrate distinct components of seasonal light input differentially influence {Psi}, , and {tau}, and suggest the possibility of separate mechanisms driving the persistent changes in circadian behaviors mediated by seasonal light.

neuroscience↗