How does peppermint affect mice? - briefly
Peppermint extracts, delivered orally or by inhalation, cause a dose‑dependent decrease in nociceptive responses and exhibit anxiolytic effects in laboratory rodents. The essential oil also modifies locomotor activity and influences gastrointestinal motility.
How does peppermint affect mice? - in detail
Peppermint (Mentha piperita) exerts multiple physiological and behavioral effects on laboratory mice when administered orally, topically, or via inhalation.
Acute exposure to essential oil vapors reduces locomotor activity within minutes. Respiratory rate declines, accompanied by a temporary decrease in heart rate. These changes correspond to activation of transient receptor potential melastatin‑8 (TRPM8) channels in sensory neurons, which mediate cooling sensations and modulate autonomic output.
Chronic administration (daily doses of 50–200 mg kg⁻¹) produces the following outcomes:
- Gastro‑intestinal motility: increased peristaltic waves, accelerated gastric emptying, and reduced incidence of constipation.
- Metabolic parameters: lower blood glucose levels, enhanced insulin sensitivity, and modest weight loss attributed to elevated thermogenesis in brown adipose tissue.
- Stress response: diminished corticosterone concentrations after restraint stress, indicating anxiolytic properties linked to γ‑aminobutyric acid (GABA) receptor modulation.
- Pain perception: elevated withdrawal thresholds in hot‑plate and tail‑flick tests, reflecting analgesic action through opioid‑receptor pathways and inhibition of inflammatory cytokines.
Dose‑response relationships reveal a biphasic pattern. Low concentrations (≤ 25 mg kg⁻¹) produce stimulant effects, whereas higher doses (> 150 mg kg⁻¹) may cause sedation and reduced exploratory behavior. Toxicological thresholds are identified at 500 mg kg⁻¹, where hepatic enzyme elevations and occasional necrosis occur.
Pharmacokinetic studies show rapid absorption through the nasal mucosa, peak plasma levels within 10 minutes, and hepatic metabolism via cytochrome P450 isoforms CYP2C19 and CYP3A4. Elimination half‑life averages 1.8 hours, with renal excretion of conjugated metabolites.
Interaction with other compounds is documented. Co‑administration with caffeine amplifies central stimulation, while simultaneous use of anticholinergic agents attenuates the gastrointestinal effects.
Overall, peppermint influences murine physiology through sensory neuron activation, modulation of autonomic functions, and interaction with metabolic and stress pathways. Careful dosing is essential to balance therapeutic benefits against potential toxicity.