U n i v e r s i d a d d e B a r c e l o n a |
Departamento de Personalidad, Evaluación y Tratamientos Psicológicos |
Cursos asistidos por ordenador a través de i n t e r n
e t |
Modelos animales
de la esquizofrenia
Effect of amphetamine on unconditioned behaviours
The next picture shows the effect of increasing doses of amphetamine on unconditioned (and conditioned) behaviours. Note how as the dose of amphetamine is increased the nature of the unconditioned behaviour changes. For example at 3mg/kg amphetamine rats engage in a lot of rearing and locomotion, whereas above 5mg/kg of the drug, gnawing, biting, sniffing, licking and rythmic head movements are the main behaviours.
Measuring amphetamine induced stereotypyWe can further illustrate the meaning of this figure by setting up an imaginary experiment in which dogs are injected with increasing doses of amphetamine (of course it would be very difficult to justify this type of experiment on dogs). We will examine three behaviours:
The results are discussed below this figure.
Notice that as we increase drug dose, the intensity of these behaviours change. As we increase dose the intensity / frequency of all the behaviours tends to increase. But importantly the rate of increase varies between the behaviours. For example tail-wagging is seen at a medium rate even under saline (control) conditions, this behaviour increases after a low dose of amphetamine (1.0 mg/kg), but declines with higher doses of the drug and is totally absent under the highest dose (10.0 mg/kg). This pattern of change is similar to the changes seen in the rats' rearing behaviour under increasing doses of amphetamine. In contrast walking is slow under control conditions, is fastest under intermediate doses of the drug ( 3-5.0 mg/kg), but slows down under the highest dose. This is similar to the effect of increasing doses of amphetamine on rats' rearing behaviour. Finally, ear-flapping is absent under low doses of amphetamine, but is emitted at a high rate under the highest doses (5-10.0 mg/kg) of the drug. Thus ear-flapping resembles sniffing and licking behaviour in the rats.
Effect of pimozide on amphetamine-induced locomotion & stereotypy The next diagram shows the effects of pimozide (a classic antipsychotic) on locomotion and stereotypy produced by increasing doses of amphetamine. Note that pimozide
These results are consistent with the hypothesis that reduction of amphetamine-induced behaviours is an indication of a drug's antipsychotic potential
Effect of clozapine on amphetamine-induced locomotion & stereotypy The next diagram shows the effects of clozapine ( an atypical antipsychotic) on locomotion and stereotypy produced by increasing doses of amphetamine. Note that clozapine
These results are NOT consistent with the hypothesis that reduction of amphetamine-induced behaviours is an indication of a drug's antipsychotic potential
|