Experimental research into addictions often uses rodents, rats and mice. According to Roser Nadal, "the animal model used is extremely reliable, giving us thorough, methodical results that can to a certain extent be applied to humans without the need to experiment directly upon them".
This research, published in Behavioural Brain Research, may help to focus preventative strategies against addiction towards those most at risk, according to their personality. "The results could be particularly useful in prevention campaigns for children, who are going through the period with the highest risk," explains Doctor Nadal.
To determine a rat's level of addiction to morphine, the researchers used the place-conditioning technique. In these tests, a special cage is used that has two very different compartments, with a distinct colour, feel and smell. The animal is placed in a compartment after being injected with the drug and is left to experiment the effects of the drug and associates them with the specific characteristics of the the compartment of the cage. On a different day, the animal is injected only with a placebo (the liquid that was used to dissolve the drug, eg, water and salt) and is placed in the other compartment of the cage. When this has been done several times over the period of a few days, the rat is left free and we observe which of the two compartments it prefers. The more the animal likes morphine, the more time it will spend in the compartment that it associated with the effects of th
Source:Universitat Autonoma de Barcelona