Search

Food is not only necessary for our survival but also elicits pleasure. However, when a novel food is followed sometime later by nausea or sickness animals form a long-lasting association to avoid that food. This phenomenon is called the 'Garcia effect'. We hypothesized that lipopolysaccharide (LPS) could be used as the sickness-inducing stimulus to produce a Garcia-like effect in inbred and wild populations of Lymnaea stagnalis. We first demonstrated that the injection of 25 μg (6.25 µg/mL) of Escherichia coli-derived LPS serotype O127:B8 did not by itself alter snails' feeding behavior. Then we showed that the presentation of a novel appetitive stimulus (i.e., carrot slurry) and LPS resulted in a taste-specific and long-lasting feeding suppression (i.e., the Garcia-like effect). We also found strain-specific variations in the duration of the long-term memory (LTM). That is, while the LTM for the Garcia-like effect in W-strain snails persisted for 24h, LTM persisted for 48h in freshly collected Margo snails and their F1 offspring. Finally, we demonstrated that the exposure to a non-steroidal anti-inflammatory drug, aspirin (acetylsalicylic acid) before the LPS injection prevented both the LPS-induced sickness state and the Garcia-like effect from occurring. The results of this study may pave the way for new research that aims at (1) uncovering the conserved molecular mechanisms underlying the Garcia-like effect, (2) understanding how cognitive traits vary within and between species, and (3) creating a holistic picture of the complex dialogue between the immune and central nervous systems., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (Copyright © 2023 Elsevier Inc. All rights reserved.)

California mice (Peromyscus californicus) breed primarily during the winter rainy season and generally terminate breeding during the dry summer months. This pattern of reproduction could be regulated by day length, availability of green vegetation, or water availability. The effects of photoperiod and green vegetation on reproduction were examined in Experiment 1 by housing adult male P. californicus either in long (LD 14:10) or short (LD 8:16) photoperiods for 10 weeks with ad lib food and water availability. A subset of animals in each photoperiod treatment group also received supplements of fresh spinach thrice weekly. The effects of water availability were examined in Experiment 2 by housing adult males in long day length conditions for 10 weeks with ad lib or restricted (50% of ad lib) water availability. Neither photoperiod nor availability of green plant food significantly affected reproductive function in male California mice, although animals in long days with green food supplements displayed elevation of some reproductive organ masses. Short days did not suppress plasma LH or prolactin levels. Male P. californicus provide extensive care of the young during the short days of winter. The absence of photoperiod-induced changes in prolactin levels is consistent with the observation that elevated plasma prolactin titers are associated with male parental care in this species. In contrast, water restriction (simulated summer drought) reduced reproductive organ masses, as well as plasma levels of prolactin, and may act as an environmental cue to terminate breeding. Thus, water availability may regulate breeding in this species independently of photoperiod and food availability.