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.