Question

1. How general anaesthetic drugs are administered on laboratory animals ( mouse and rat)?

2. What the effects of administration of general anaesthetic drugs on the physiological abilities of laboratory animals? i.e. mouse and rat.

3. Why is it important to use general anaesthetic drugs for a research study on laboratory animals?

4. Why is it important to know the suitable route of administration of laboratory animals?

5. How proper injection techniques help with research works on laboratory animals?

Answer 1

ans:An anesthetic or anaesthetic is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness.

1)Laboratory animals(mouse and rat) are sometimes used in experimental clinical studies such as pre-marketing of a drug or a medical-surgical device or in regenerative medicine and surgery.

The anesthesia protocols influence the survival of laboratory animals and can also greatly affect the experimental data results. To date, there is no anesthetic protocol widely used for single laboratory animal species.

The murine species (rats and mice) is the most used model in various research fields, such as for organ transplantation, regenerative medicine and imaging.

Four aspects are of paramount importance for a correct management of the trial: a correct inhalation anesthetic, effective anesthesia, the duration of the entire experimental procedure and a correct protocol of endotracheal intubation .

In general, anesthesia can affect some physiological parameters, such as pressure, blood oxygen saturation, cerebral blood flow and many other factors that may affect the postoperative follow-up. The majority of anesthetic agents decrease the cerebral metabolism and they often affect the neurotransmission of nerve impulses, for which, the body temperature and other physiological parameters, should be monitored during anesthesia.

The anesthesia is commonly used in laboratory animals, and can be induced by different methods depending on the type of study and the type of animal taken .

2) Anesthetic agents which are most frequently used (ketamine, propofol, isoflurane/halothane) to induce and maintain anesthesia in laboratory animals influence the carbon dioxide tension in arterial blood or exhaled and can cause respiratory acidosis. They must therefore be carefully monitored all the vital parameters of the animal and restoring fluid and electrolyte balance in the event that it were altered.

Ketamine typically increases cerebral blood flow and indirect sympathetic mimetic effects on the metabolism of the brain increasing the plasma concentration of norepinephrine and, being an antagonist of NMDA receptors, it can also determine neuronal damage known as Olney lesions .

Although rectal temperature values were reduced to some degree in each group, the most profound hypothermia. Propofol is a short-act anesthetic drug that readily crosses the blood-brain barrier; its effect starts after a minute. It is rapidly cleared from plasma, and the consciousness returns more quickly with propofol that with other anesthetic drugs.

  The anesthesia can also affect the blood glucose levels and lipid concentration that may indirectly affect brain metabolism

The cerebral metabolism may also be affected by changes in body temperature, and in particular that hypothermia is common during prolonged anesthesia in small animals

. Hyperglycemia, for example, can greatly increase the risk of global cerebral ischemia since the fluctuations in blood glucose levels can greatly affect brain function by modulating the mechanisms and neuroprotective properties of the blood-brain barrier.

Blood glucose levels should be monitored carefully during maintenance of anesthesia in order to avoid both hyper- and hypoglycemia . Medetomidine commonly used to sedate laboratory animals can cause hypotension and respiratory depression, especially at low doses, while not reduce cerebral blood flow

3) Veterinary anesthesia is anesthesia performed on non-human animals by a veterinarian or a Registered Veterinary Technician. Anesthesia is used for a wider range of circumstances in animals than in people, due to animals' inability to cooperate with certain diagnostic or therapeutic procedures. Veterinary anesthesia includes anesthesia of the major species: rat and mice

Small animals are most often placed under general anesthesia due to the types of procedures typically performed, the small size of the patient, their suitability to general anesthesia, and the greater degree of control.

A balanced anesthesia protocol can be used whereby different drugs with different effects are used so that a high dose of just one drug can be avoided.

For example, combining a sedative and an opioid will permit less inhalant anesthesia to be used, improving cardiovascular stability.

4) Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure.

For all species, many different routes are available for administration of substances. The research team should be aware of reasons for selecting specific routes and of training and competency necessary for personnel to use these routes effectively.

Once a route is selected, issues such as volume of administration, site of delivery, pH of the substance, and other factors must be considered to refine the technique. Inadequate training or inattention to detail during this aspect of a study may result in unintentional adverse effects on experimental animals and confounded results.

5) The injection route of delivery is the most efficient means of delivering substances to animals because it bypasses the need for solute absorption.

With this method, substances are administered as a bolus or infusion directly into blood vessels on either an acute or chronic basis . Precision electronic infusion pumps equipped with alarms to indicate flow interruptions and microdrop infusion sets are used to ensure accurate chronic injection delivery of many substances;

however, less expensive precision and spring-operated disposable pumps have become available for this purpose in recent years and may represent a more economical alternative for experimental intravenous substance delivery, depending on the nature of the material to be administered and the duration of treatment.

This technique is vastly used for animals with small bodie like rat and mice

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