Direct microinjection of cathinone into the rat brain produces discriminative stimuli

Rats were trained to discriminate IP administration of 800 micrograms/kg cathinone using a food-motivated, two-lever discrimination procedure. Following training, 800 micrograms/kg cathinone discrimination was produced (generalized) by lower cathinone doses in a dose-responsive manner after IP administration; an ED50 value of 330 micrograms/kg was calculated. Subsequently, guide cannulae were implanted into the lateral ventricle and bilaterally into the nucleus accumbens. After recovery, injections were made via cannulae that extended 0.5 mm past the tip of the guide cannulae. ICV administration of 256 micrograms cathinone/rat produced discriminative responding on the cathinone-appropriate lever to the same degree as did the peripherally administered training dose of cathinone. Decreasing ICV doses produced decreased discriminative performance and allowed the calculation of an ED50 value of 90.5 micrograms. Likewise, administration of 64 micrograms cathinone/nucleus accumbens (for a total of 128 micrograms/rat) substituted for the IP training dose of cathinone. These results evidence the central mediation of the cathinone-induced discriminative stimulus cue and show that administration of cathinone into the nucleus accumbens is sufficient to produce these stimuli. Thus, these data suggest that receptors in the nucleus accumbens are important for the discrimination of this psychostimulant.