Study Of The Effects Of PKCI/HINT1 Gene Knocking Out On Cocaine-Induced CPP And Its Mechanism

Protein Kinase-C Interacting ProteinⅠ(PKCI/HINT1) is a smallintracellular protein belonging to histidine triad protein family, which isbroadly present in the mammalian brain. Although PKCI/HINT1 is expressedin relatively high concentration in CNS, including some areas involved inschizophrenia and addiction like cortex, striatum, nucleus accumbens, and itsstructure has been well characterized, little is known about itspathophysiology function, especially in CNS. A recent study in our lab showsthat PKCI/HINT1 KO mice displayed higher signs of schizophrenia andbipolar-like behavior compared to their wild type littermates, suggesting thatPKCI/HINT1 maybe play a role in some mental disorder. Since ome evidencesshow there are high rates of co-morbidity of drug addiction with mentaldisorder, so in this study we want to assess whether PKCI/HINT1 also plays arole in addiction.Conditioned Place Preference (CPP) is thought to be one major method ofmeasuring the effect of rewarding, we investigated drug-seeking behavior inPKCI/HINT1 KO mice and WT mice with cocaine induced conditioned placepreference (CPP) method.Behavioral Experiment: The behavioral procedure is tested in a 2compartments apparatus inserted into an open field chamber equipped with 16infrared beams. The two compartments provide distinct tactile environmentsto maximize contextual differences; they differ in floor conditions, one has awire mesh floor, and the other has a grid rod floor. Compartments areseparated by an opaque Plexiglas wall pierced with a removable guillotinedoor. The conditioned place preference (CPP) test is divided into two phases:preconditioning, and conditioning. Pre-test: during the 3 days preconditioningphase, the separating door is removed and mice can explore freely the entireapparatus for 20 min; locomotion activity and time spent in each compartment are monitored. Time in seconds is averaged and mice's preferred or nonpreferred compartments are assigned accordingly. The conditioning is a 4days phase with the presence of the guillotine door; on day 1 and 3 mice areconfined to the preferred compartment for 20 min immediately after they hadreceived saline. On day 2 and 4 they are treated with cocaine hydrochlorideand confined to the other compartment (non preferred compartment) for 20min. For each animal, during the conditioning phase, one of the patterns isconsistently paired with a saline injection and the other one with a druginjection. Test: on day 5 mice are allowed to access freely to bothcompartments for 20 minutes and the locomotion activity and time spent inboth compartments are recorded. The conditioned place preference isevaluated by calculating the difference between the time spent in thedrug-paired (non-preferred) compartment after the conditioning and beforethe conditioning.Saline controls are conducted prior to the drug conditioning following thesame protocol with saline being administered on days 1, 2, 3 and 4 of theconditioning phase. Thus each animal was its own control.Our data indicates that PKCI/HINT1 KO mice show higher CPP than WTmice, suggesting that PKCI/HINT1 may play a role in drug-seeking behavior.This study provides the evidence for the potential role of PKCI/HINT1 inaddiction.Data were analyzed with a 2-way ANOVA genotype x treatment and whensignificant (p＜0.05) comparison between groups were performed using aBonferroni post hoc test.