How does mint affect rats? - briefly
Mint consumption suppresses appetite and slows gastrointestinal motility in rats, resulting in reduced weight gain. It also produces mild sedative effects by stimulating olfactory receptors.
How does mint affect rats? - in detail
Mint (Mentha spp.) exerts several measurable effects on laboratory rats when administered orally, topically, or via inhalation. Acute exposure to essential oil concentrations above 0.5 % v/v produces rapid respiratory irritation, increased heart rate, and transient locomotor hyperactivity. Sub‑lethal doses (0.1–0.3 % v/v) yield modest reductions in food intake and body weight gain, attributable to the pungent flavor and activation of bitter‑taste receptors.
Neurochemical analyses reveal that menthol, a primary constituent of mint, modulates transient receptor potential melastatin‑8 (TRPM8) channels in dorsal root ganglia, leading to altered nociceptive signaling. Chronic administration (daily 30 mg/kg for 4 weeks) results in:
- Decreased dopamine turnover in the striatum.
- Elevated serotonin levels in the hippocampus.
- Reduced expression of c‑Fos in the hypothalamic paraventricular nucleus.
These changes correlate with observed behavioral shifts: reduced anxiety‑like responses in elevated‑plus‑maze tests, diminished exploratory activity in open‑field assays, and modest impairments in spatial memory during Morris‑water‑maze trials.
Gastrointestinal effects include increased gastric motility and secretion of mucus, which protect the mucosal lining against ulcerogenic agents. Histological examinations after 2 weeks of 0.2 % mint extract in drinking water show thicker mucosal layers and lower incidence of ethanol‑induced lesions.
Toxicological assessments indicate a median lethal dose (LD₅₀) of approximately 2 g/kg body weight for menthol, classifying it as low‑to‑moderate toxicity in rodents. Sub‑lethal exposure does not produce organ‑specific damage; liver enzyme activities (ALT, AST) remain within normal ranges, and renal function markers (creatinine, BUN) are unchanged.
Overall, mint influences rat physiology through sensory irritation, modulation of neurotransmitter pathways, and gastrointestinal protection, with effects dependent on concentration, route of administration, and duration of exposure.