Induction of Catalepsy in Mice/Rats

What is Catalepsy??

• Catalepsy is a nervous condition characterized by muscular rigidity and fixity of posture regardless of external stimuli, as well as decreased sensitivity to pain.

• Waxy flexibility and cerea flexibilitas

Causes of Catalepsy

• Catalepsy is a symptom of certain nervous disorders or conditions such as Parkinson's disease and epilepsy.

• It is also a characteristic symptom of cocaine withdrawal. • It can be caused by schizophrenia treatment with anti-

psychotics such as haloperidol and by the anaesthetic ketamine.

• Protein kinase A has been suggested as a mediator of cataleptic behaviour.

• Other causes of catalepsy include reuptake inhibitors of adrenergic neurotransmitters such as Reserpine.

Symptoms of Catalepsy

• Symptoms include: rigid body, rigid limbs, limbs staying in same position when moved (waxy flexibility), no response, loss of muscle control, and slowing down of bodily functions, such as breathing

Induction of Catalepsy in Mice/Rats• Neurotensin administered intra cerebroventricularly

(ICV 0.5, 1.0 and 2.0 μg) produced catalepsy in a dose-dependent fashion in mice.

• A significant effect was observed at 2.0 μg and a maximal effect 2–3 h after injection.

• The NT-induced catalepsy was inhibited by pretreatment with atropine, trihexyphenidyl or biperiden (each drug, 0.8–5.0 mg/kg, IP), anticholinergic drugs, and L-DOPA (100, 200 mg/kg, IP).

• Pinch-induced catalepsy is readily obtained in mice following repeated administration of strong pinches at the scruff of the neck.

• This catalepsy outlasted the pinch by minutes and was more easily induced on retests 48 hr after the initial acquisition tests.

• Repetitive tail pinches and/or exposure to the testing procedure without pinches also resulted in immobility; however, this was weak in magnitude and short in duration.

• Haloperidol 1mg/kg IP has been used many a times to induce catalepsy in rats.

• Mice : Haloperidol 2mg/kg IP

Observation

• Catalepsy, defined as a reduced ability to initiate movement and a failure to achieve correct posture, is measured by the bar test.

• Mice are positioned so that their hindquarters are on the bench and their forelimbs rest on a 1-cm diameter horizontal bar that is 4 cm above the bench.

• Mice are judged to be cataleptic if they maintain this position for 30s or more.

• The length of time for which the mouse maintains this position is recorded with a stopwatch with a maximum duration of 180s.

• This procedure is performed 30 min after the administration of haloperidol (2 mg/kg, IP).

• If the mouse holds the position for 30s or more then catalepsy is said to be induced.

Catalepsy

Why induce catalepsy?

• To observe the effects of dopamine blocking agents on motor system

• To get an idea of clinical symptom of catalepsy• To produce models for testing newer drugs for

diseases like Parkinson’s disease which are based on dopamine hypothesis.