Locomotor sensitization to cocaine and nicotine enhanced nicotine-CPP in the adult zebrafish

A PISERA-FUSTER AND R BERNABEU

Mar del Plata

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2018

SAIC-SAI-SAFIS

Locomotor sensitization is a convenient behavioraltest to evaluate the effects of psychostimulants. Conditioning place preference(CPP) is an associative learning procedure to examine the rewarding propertiesof drugs. Since sensitization was not previously evaluated for nicotine andcocaine reward in zebrafish, we first analyzed sensitization to both drugs byexposing zebrafish five days (20 min-day) to either drug followed by five daysof abstinence before a challenge dose to evaluate these drug effects onzebrafish locomotor activity. Then, we selected the lower dose of nicotine thatinduced sensitization which interestingly cannot induce CPP. Locomotorsensitization was increased by 103% with nicotine and 166% with cocaine.Following this, sensitized zebrafish were trained using a two-chambernicotine-driven CPP protocol. Cocaine-sensitized animals showed the highestscore for the establishment of nicotine-CPP compared to previouslynicotine-sensitized fish. Furthermore, detailed behavioral and molecularanalyses confirmed these findings. The levels of nicotinic receptor subunits α7and α6, but not β2, mRNA were increased in both nicotine- andcocaine-sensitized zebrafish. Only cocaine-sensitized zebrafish showedsignificant increases of the dopamine transporter (DAT). Nicotine-CPP but notcontrol CPP showed similar values compared to sensitized animals forpractically all the markers measured, suggesting that some specific markers aresensible to both processes. These findings suggest that doses of nicotine thatcan induce sensitization might be not enough to induce nicotine-placeconditioning. On the other hand, suggest that previous exposure to low doses ofdrugs of abuse can increase subjects? sensitivity to the rewarding propertiesof drugs of abuse.