How does mint affect mice? - briefly
Menthol and other volatile oils in mint serve as strong olfactory repellents, lowering mouse activity and feeding behavior in environments where the herb is applied. Ingested mint can also cause mild gastrointestinal irritation, leading to reduced weight gain.
How does mint affect mice? - in detail
Mint (Mentha spp.) contains menthol, menthone, and a variety of volatile terpenes that interact with sensory receptors in rodents. When administered orally, topically, or via inhalation, these compounds produce measurable physiological and behavioral changes.
Physiological responses
- Activation of the TRPM8 ion channel in peripheral nerve endings generates a cooling sensation, leading to reduced core body temperature and altered thermoregulatory behavior.
- Stimulation of olfactory receptors triggers increased sniffing frequency and transient changes in heart rate, reflecting acute sensory arousal.
- Menthol exerts mild analgesic effects by modulating voltage‑gated sodium channels, resulting in higher pain‑threshold scores in hot‑plate and tail‑flick assays.
- Metabolic studies show a modest rise in oxygen consumption and a shift toward fatty‑acid oxidation after short‑term exposure.
Behavioral outcomes
- Preference tests reveal a consistent attraction to low‑concentration mint vapors, while higher concentrations produce avoidance and reduced locomotor activity.
- In open‑field arenas, mice exposed to 0.5 % menthol solution display increased exploratory bouts and reduced thigmotaxis, suggesting anxiolytic‑like effects.
- Chronic dietary inclusion of dried mint leaves (2 % of chow) leads to a gradual decline in body weight gain, likely mediated by appetite suppression and enhanced energy expenditure.
Toxicological considerations
- Acute oral LD₅₀ for menthol in mice exceeds 5 g kg⁻¹, indicating low acute toxicity.
- Subchronic exposure at 1 % dietary menthol for 90 days produces no significant alterations in liver enzyme activity, renal histology, or hematological parameters.
- High‑dose inhalation (>5 % menthol aerosol) can cause respiratory irritation, bronchoconstriction, and transient hypoxia.
Experimental protocols
- Inhalation study – Place mice in a sealed chamber; deliver mint oil vapor at 0.1, 0.5, and 1 % concentrations for 30 min; record respiratory rate, body temperature, and locomotion.
- Oral supplementation – Mix ground mint leaves into standard chow; monitor daily food intake, body weight, and glucose tolerance over 8 weeks.
- Topical application – Apply 10 µL of 2 % menthol cream to the dorsal skin; assess nociceptive thresholds at 15‑, 30‑, and 60‑minute intervals.
Collectively, data indicate that mint exerts dose‑dependent cooling, analgesic, metabolic, and behavioral effects in mice, with a wide safety margin for short‑term use.