Biology subjects

Santollo, J.

Publications and source records attributed to Santollo, J..

4 recordsLinked to original sources

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↗

bioRxiv2025

Drinking microstructure analysis of direct controls of water intake in male and female rats.

Measures of rodent drinking (lick) patterns are used to test how various manipulations affect fluid intake. Decades of research indicate that manipulating the satiating potency of a stimulus affects the number of licking bursts whereas manipulating the hedonic value of the solution affects the size of the licking bursts or rate of licking. This type of analysis has been largely applied to manipulations that modulate drinking that is already occurring (i.e., indirect controls or modulators of intake), but there is a dearth of studies with detailed measures of licking in response to stimuli that are primary drivers of intake (i.e., direct controls). A better understanding of licking behavior in response to direct controls of fluid intake could provide insight into how drinking is stimulated. Accordingly, we analyzed lick patterns after varying doses of primary drivers (direct controls) of intake, angiotensin II, hypertonic saline, or carbochol, in male and female rats. As expected, all treatments dose-dependently increased licks for water. Analysis of licking patterns revealed dose-related increases in burst number after treatment with all stimuli, but dose did not predict burst size or lick rate. Together with previous work on licking patterns these data suggest that direct controls of water intake are more related to processes associated with satiety than to changes in hedonic value of the consumed substance.

neuroscience↗

bioRxiv2023

Limited effects of dehydration on object discrimination in the novel object recognition paradigm in young and middle-aged male and female rats.

Dehydration is associated with impaired cognitive function in humans. Limited animal research also suggests that disruptions in fluid homeostasis impair performance in cognitive tasks. We previously demonstrated that extracellular dehydration impaired performance in the novel object recognition memory test in a sex and gonadal hormone specific manner. The experiments in this report were designed to further characterize the behavioral effects of dehydration on cognitive function in male and female rats. In Experiment 1, we tested whether dehydration during the training trial in the novel object recognition paradigm would impact performance, while euhydrated, in the test trial. Regardless of hydration status during training, all groups spent more time investigating the novel object during the test trial. In Experiment 2, we tested whether aging exacerbated dehydration-induced impairments on test trial performance. Although aged animals spent less time investigating the objects and had reduced activity levels, all groups spent more time investigating the novel object, compared to the original object, during the test trial. Aged animals also had reduced water intake after water deprivation and, unlike the young adult rats, there was no sex difference in water intake. Together these results, in combination with our previous findings, suggest that disruptions in fluid homeostasis have limited effects on performance in the novel object recognition test and may only impact performance after specific types of fluid manipulations.

animal behavior and cognition↗

bioRxiv2021

The influence of sex, hormone status, and growth rate on dietary isotope fractionation: a case study with laboratory rats

Stable isotope analysis is increasingly used to discern ecological differences within and among species, especially those difficult to observe. In applied ecological studies, variations in stable isotope composition are often attributed to foraging behavior or trophic ecology rather than fractionation during metabolic processes. One physiological difference among individuals is gonadal hormone levels, which affects food intake, metabolism, and locomotor activity. However, it is unclear how these effects- isolated from ecology- affect metabolic dynamics and expression in stable isotope analysis. Here, we test the linkage between gonadal hormones and isotopic heterogeneity among individuals with captive rats. We found that sex and removal of gonadal hormones are factors either individually or interactive for {delta}15N and {delta}13C values in serum and blood as well as {delta}15N values of muscle and liver. Furthermore, the degree of fractionation in these tissues is related to growth rate. Gonadectomization also affected isotopic composition for liver {delta}13C values and kidney {delta}15N values, but fat {delta}13C values were affected only by sex. The pattern of differentiation between groups was most different for kidney {delta}15N and {delta}13C values, which also had the largest isotopic variability among groups. Overall, isotopic variation within one tissue for the four groups demonstrated up to 1{per thousand} difference in {delta}13C and {delta}15N values suggesting that sex based within population variations should into consideration these potential physiological effects. What is already knownThere are isotopic differences between diet and various consumer tissues with variability among individuals, which is often characterized based on captive feeding studies. Effects of protein quality and quantity, variable growth rate based on ontogeny, and differences between sexes have been tested thus far in experiments. Furthermore, it is known that gonadal hormones affect energy regulation with difference in weight gain, which suggest differences in extent and rate of biochemical processes. What this study addsThis study demonstrates effects of gonadal hormone status with metabolic biochemistry by using stable isotopes of carbon and nitrogen as dietary tracers. We find that gonadal hormone status accounts for some isotopic heterogeneity among individuals, which should be considered when interpreting stable isotope data from wild specimens. Rather than attributing isotopic differences to ecological factors, such as foraging preference, there may be underlying physiological processes that differentiate groups based on ontogeny and sex.

ecology↗