Treball Final de Grau en Psicologia. Codi: PS1048. Curs 2013-2014It has been proposed that neuroadaptations underlying psychomotor sensitization induced by
repeated administration of drugs of abuse are associated with pathological, excessive motivation
toward drugs and drug-associated stimuli, and are involved in facilitation and maintenance of
addictive behavior. It has been shown that cocaine-induced psychomotor sensitization is
sensitive to the effects of conditioning;
expression of sensitization appears to be dependent on
the context in which it was acquired.
In this regard, it has been proposed that cues associated
with repeated administration of drugs can trigger motivational states that can in turn facilitate
drug seeking and intake. Therefore, conditional effects are important to study in the context of
drug addiction. Research focusing on consolidation and expression of memories supporting cueinduced
behaviors, is currently paying considerable attention to the noradrenergic (NE) system,
and in particular to α₁ and β-adrenergic receptors. First, our studies in the laboratory focused on
exploring the effects of propranolol (nonspecific antagonist of b-adrenergic receptors), with
prior repeated administration of cocaine / saline (inducing conditioned sensitization) in the same
context (CS +). Sensitized animals showed further drug-free, context-dependent hiperactivation,
an effect that was prevented by propranolol. The present study further explored the role of NE
receptors by using prazosin, a selective α-adrenergic receptors antagonist. Male DBA/2J
animals received intraperitoneal injections of 0 or 20 mg/kg of cocaine on alternate days (Mon,
Wed, Fri, Mon, Wed, Fri) in order to achieve psychomotor sensitization. Locomotor activity of
animals treated with cocaine was always assessed in a chamber with a particular flooring
configuration (grid or hole; counterbalanced), CS+. This design was also used for saline treated
animals (CS-). On day 15 of the experiment all animals were presented with the CS +; we
obtained conditioned hyperactivity in the group previously treated with cocaine. Prazosin did
not block this effect. The finals results were that prazosin has no effect on repeated
administration of cocaine-induced conditioned hyperactivity
