How does a rat show an allergic reaction to food? - briefly
Rats reveal food‑induced allergies by exhibiting itching, skin swelling, watery eyes, labored breathing, diarrhea, and by showing elevated serum IgE and histamine levels.
How does a rat show an allergic reaction to food? - in detail
Rats exposed to dietary allergens exhibit a series of observable changes that indicate an immune‑mediated reaction. The response can be divided into acute clinical signs, physiological alterations, and measurable immunological markers.
Acute clinical signs appear within minutes to hours after ingestion and include:
- Scratching or grooming of the face and paws, often directed toward the mouth region.
- Swelling of the periorbital area and muzzle, sometimes progressing to generalized facial edema.
- Increased respiratory rate, audible wheezing, or labored breathing.
- Diarrhea or soft feces, sometimes accompanied by blood.
- Reduced activity, lethargy, and loss of appetite.
Physiological alterations detectable by researchers involve:
- Elevation of core body temperature (hyperthermia) measured with implanted telemetry devices.
- Changes in heart rate and blood pressure recorded via catheterization or non‑invasive tail‑cuff systems.
- Increased vascular permeability leading to plasma leakage, assessed by Evans blue dye extravasation.
- Bronchoconstriction quantified through plethysmography.
Immunological markers confirm the allergic nature of the response:
- Serum IgE specific to the offending food protein rises within 24–48 h; enzyme‑linked immunosorbent assay (ELISA) quantifies this increase.
- Elevated levels of histamine, tryptase, and prostaglandin D₂ in plasma, measured by immunoassays.
- Cytokine profile shifts toward Th2 dominance, with higher interleukin‑4, interleukin‑5, and interleukin‑13 concentrations in splenic or lymph node cell cultures.
- Mast cell degranulation observed in skin and intestinal biopsies stained with toluidine blue.
Behavioral monitoring complements physiological data. Video tracking systems record increased grooming bouts, reduced locomotion, and altered nesting behavior. These metrics correlate with the severity of the reaction and provide a non‑invasive readout.
In experimental settings, investigators often combine the above observations to construct a comprehensive picture of the rat’s allergic response to food. The integration of clinical signs, physiological recordings, and immunological assays yields a reliable assessment of allergenicity and the efficacy of therapeutic interventions.