What should be injected into a rat? - briefly
«Physiological saline» or another sterile isotonic carrier is typically injected to deliver the experimental compound at the calculated dose. This approach ensures consistent distribution and minimizes adverse reactions.
What should be injected into a rat? - in detail
Injectable agents for laboratory rats must be selected according to experimental objectives, physiological compatibility, and regulatory standards.
Common categories include:
- Anesthetic compounds – injectable formulations such as ketamine‑xylazine, medetomidine, or isoflurane‑compatible agents provide rapid induction and reliable maintenance of surgical depth. Dosage is expressed in mg kg⁻¹ and adjusted for strain, age, and weight.
- Analgesic additives – buprenorphine, meloxicam, or carprofen are administered to control postoperative pain; dosing follows manufacturer guidelines, typically 0.05–0.1 mg kg⁻¹ for buprenorphine.
- Tracer substances – fluorescent dyes (e.g., FITC‑dextran), radiolabeled markers, or magnetic nanoparticles enable visualization of vascular permeability, organ distribution, or neuronal pathways. Concentrations are calibrated to achieve detectable signal without toxicity.
- Pharmacological agents – agonists, antagonists, enzyme inhibitors, or hormones are delivered to modulate specific pathways. Precise molarity and volume (often ≤0.5 mL) minimize fluid overload.
- Gene‑delivery vectors – adeno‑associated virus, lentivirus, or plasmid DNA in lipid nanoparticles facilitate transduction or expression studies. Titers are expressed as viral genomes per milliliter; injection volume and route (intracerebral, intraperitoneal, or tail‑vein) determine transduction efficiency.
Key procedural considerations:
- Route of administration – intravenous injection requires a catheterized tail vein or retro‑orbital sinus; intraperitoneal delivery demands a sterile needle inserted at a shallow angle to avoid organ injury; subcutaneous injection is performed in the dorsal flank for slow release.
- Vehicle composition – isotonic saline, phosphate‑buffered saline, or specialized carrier solutions maintain osmolarity and pH; inclusion of surfactants or stabilizers prevents precipitation.
- Sterility and endotoxin levels – all preparations must be filtered through 0.22 µm membranes and tested for endotoxin concentrations below 0.1 EU mL⁻¹ to avoid inflammatory responses.
- Dose calculation – convert target dose to µL using the formula: volume = (weight × dose) / concentration. Verify calculations with independent software or manual cross‑check.
- Ethical compliance – protocols require approval from an Institutional Animal Care and Use Committee; documentation must include justification of agent choice, anticipated adverse effects, and humane endpoints.
Monitoring after injection includes observation of respiration, motor activity, and injection site for signs of distress or leakage. Immediate intervention with reversal agents (e.g., atipamezole for medetomidine) or supportive care is mandated when adverse reactions occur.
Selection of the appropriate injectate, combined with rigorous preparation and administration standards, ensures experimental validity and animal welfare.