Sexual differences in responses of meadow voles to environmental cues in the presence of mink odor

Oregano leaf odor regulates sodium chloride consumption in mice

This study explores how the odor of oregano and its active component, carvacrol, influence salt preference in mice. Using a 2-bottle choice test (distilled water vs 0.15 m NaCl), 66 C57BL/6J mice were exposed to oregano odor. Female mice showed a significant reduction in saline intake with oregano or carvacrol exposure, while the effect was lower in males. Carvacrol was identified in dried oregano using gas chromatography-mass spectrometry (GC-MS) with headspace-solid-phase microextraction (HS-SPME). Neurologically, oregano odor increased c-Fos immunoreactivity in the ventral bed nucleus of the stria terminalis, a region regulating salt appetite. These results suggest that oregano odor decreases salt preference, partly due to carvacrol, which stimulates brain areas controlling salt appetite. This study highlights the role of olfactory cues in modulating dietary behavior and suggests potential applications for managing salt consumption in health contexts.

Impact of food availability and predator cues on meadow vole response to social vs. non-social odorants

The risk of predation and food deprivation may alter the degree to which animals associate with conspecifics. We examined if food deprivation, the risk of predation, or simultaneous exposure to both altered meadow voles’ preference for odour cues in a way that adheres to the terminal investment, safety in numbers, or avoidance hypotheses. Satiated or food-deprived meadow voles were given the choice to investigate either opposite-sex conspecific bedding, same-sex conspecific bedding, clean bedding, or self-bedding when exposed to mink urine or olive oil. Mink urine and food deprivation did not impact the amount of time meadow voles spent with each type of bedding, but meadow voles did begin investigating more quickly when experiencing either or both stressors. However, food deprivation and mink urine did not have an additive impact on any measured variable. Further research is needed to determine if the terminal investment hypothesis is the hypothesis that best describes the mating behaviour of meadow voles facing one or multiple stressors.