Biology subjects

Kaczmarczyk-Jarosz, M.

Publications and source records attributed to Kaczmarczyk-Jarosz, M..

4 recordsLinked to original sources

bioRxiv2026

The effect of preproenkephalin gene deletion on heart function in mice

Enkephalins, the endogenous ligands of the - and {delta}-opioid receptors, are abundantly expressed in the nervous system and peripheral organs, including the heart. Accumulating evidence suggests that they participate in cardiac development and act as autocrine and paracrine modulators of heart activity. Here, we investigate the role of enkephalins in cardiac physiology using a newly generated mouse strain with a complete ablation of the preproenkephalin (Penk) gene. We find that, although adult mutant mice weighed less, the mutation caused no apparent changes in behavioral phenotype, no increase in anxiety-like behaviors, and only a mild reduction in locomotor activity. There was no effect of Penk deletion on heart weight or size. A comprehensive analysis of left ventricular function using MRI revealed normal basal cardiac performance, except for a significant reduction in the peak fill and ejection rates. There were no significant effects of Penk deletion on left ventricular function after {beta}1-adrenergic stimulation with dobutamine. At the same time, we observed the expected significant differences in heart size and function between male and female mice. In conclusion, our data show that enkephalins are not essential for normal heart development and have a moderate impact on adult heart function under basal conditions.

neuroscience↗

bioRxiv2025

Decreased social, drug, and food reward sensitivity in adolescent mice

Adolescence shapes adaptive adult behaviors. Most studies compare single adolescent and adult age groups using only one type of reward, limiting insight into developmental trajectories underlying behavioral change. Here, we investigated how social, cocaine, and palatable food rewards become associated with environmental contexts in female and male C57BL/6 mice across early- (pubertal onset), mid- (peripubertal phase), and late- (sexual maturity) adolescence, compared to adults. Using the conditioned place preference (CPP) task, we found that generally all rewards induced place preference for the reward-associated context, with only minor effects of sex. In contrast, age significantly influenced CPP expression. Adolescent mice exhibited a significantly reduced CPP compared to adults in palatable food and social CPP paradigms, evident in both decreased mean conditioned context preference and lower proportion of animals that developed a preference after conditioning. Cocaine CPP was not significantly affected by age. Direct comparisons across CPP task outcomes further confirmed that age, rather than reward type or sex, was the primary factor influencing the magnitude of CPP. Specifically, mid- and late-adolescent mice showed reduced mean reward CPP, and mid-adolescents were less likely to express a reward preference relative to adults. Based on the behavioral analyses, we conclude that the lower expression of preference for a conditioned context in adolescent animals is due to developmental changes in reward sensitivity, rather than deficits in learning or higher novelty-seeking behavior.

animal behavior and cognition↗

bioRxiv2025

Changes in social reward across adolescence in male mice

In humans, adolescence is a time of dynamic behavioral and emotional changes, including a transient decrease in affect associated with being among family members. It is not clear if a similar change occurs in rodent species used to model human psychiatric disorders. Here, we investigated the developmental profile of the rewarding value of interactions with siblings across adolescence in male mice, using the social conditioned place preference task. We found that the reward value of social interactions followed a similar course to that in humans: high in early adolescence, it decreased in mid-adolescence and returned to the initial level in late adolescence. The observed change was specific to social interaction, as no age-dependent changes in preference for cocaine-conditioned context were detected. Taken together, these data show similarities between mice and humans in developmental changes in sensitivity to the rewarding effects of interactions with familiar kin.

neuroscience↗

bioRxiv2022

A robust method for measuring social reward in adult mice

Social interactions can be and often are rewarding. The effect of social contact strongly depends on circumstances, and the reward may be driven by varied motivational processes, ranging from parental or affiliative behaviors to investigation or aggression. Reward associated with nonreproductive interactions in rodents is measured using the social conditioned place preference (sCPP) paradigm, where a change in preference for an initially neutral context confirms reinforcing effects of social contact. Here, we revised the sCPP method and reexamined social reward in adult female mice. Contrary to earlier studies, we found that robust rewarding effects of social contact could be detected in adult (14-week-old) female C57BL/6 mice when the sCPP task was refined to remove confounding factors. Strikingly, the rewarding effects of social interaction were only observed among female siblings who remained together from birth. Contact with same-age nonsiblings was not rewarding even after 8 weeks of cohousing. Other factors critical for the social reward effect in the sCPP paradigm included the number of conditioning sessions and the inherent preference for contextual cues. Thus, we show that social interaction is rewarding in adult female mice, but this effect strictly depends on the familiarity of the interaction partners. Furthermore, by identifying confounding factors, we provide a behavioral model to study the mechanisms underlying the rewarding effects of nonreproductive social interaction in adult mice.

animal behavior and cognition↗