Involvement of D1 and D2 dopamine receptor in the retrieval processes in latent inhibition

• Published in: Psychopharmacology Vol. 232; no. 23; pp. 4337 - 4346
• Main Authors: Diaz, E., Medellín, J., Sánchez, N., Vargas, J. P., López, J. C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2015; Springer; Springer Nature B.V
• Subjects: Animals; Antagonist drugs; Benzazepines - pharmacology; Biomedical and Life Sciences; Biomedicine; Cognition & reasoning; Corpus Striatum - drug effects; Corpus Striatum - physiology; Dopamine; Dopamine Agents - pharmacology; Dopamine D2 Receptor Antagonists - pharmacology; Dopamine receptors; Inhibition (Neurophysiology); Inhibition (Psychology); Learning - drug effects; Learning - physiology; Male; Neurosciences; Original Investigation; Pharmacology/Toxicology; Psychiatry; Psychological research; Psychopharmacology; Rats; Rats, Wistar; Receptors, Dopamine D1 - antagonists & inhibitors; Receptors, Dopamine D1 - physiology; Receptors, Dopamine D2 - physiology; Retrieval (Memory); Sulpiride - pharmacology; Retrieval; Sulpiride; SCH-23390; Latent inhibition; Dopamine receptors
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-015-4063-2

Rationale Contemporary theories propose that latent inhibition (LI) is due to a process of interference with the context playing a key role as recovery cue. Physiological studies have demonstrated that LI is a process dependent on striatal dopamine. D2 dopamine receptors have been specifically associated with its expression, while D1 receptor has shown a limited function. However, to evaluate the role of dopamine receptors in LI, it is necessary to analyse their activity during recovery phase, where the mechanisms involved in interference processes are performed. Objective The experiments studied the involvement of the dopaminergic system in the retrieval process of LI. We analysed the effect of the systemic administration of dopaminergic D1 (SCH-23390) and D2 (sulpiride) antagonist during the test phase on LI and on its contextual specificity. Methods Animals were pre-exposed to saccharin solution and conditioned with a LiCl administration in conditioning phase. Dopaminergic antagonist drugs were administered during the test phase. Experiment 2 used the same context in all the phases. Experiment 3 used a new context during conditioning and test phase. Results The D2 antagonist increased the LI effect and, in turn, diminished the normally suppressant effect of the context shift on LI. The opposite effect was observed under the D1 antagonist administration. This drug disrupted LI and enhanced the effect that the context shift had on this cognitive process. Conclusions D2 receptor had a relevant role on retrieval processes of pre-exposure learning, while D1 receptor was related with the contextual control of conditioning.