Dihydro-β-erythroidine hydrobromide(DHβE) is a potent, oral active and competitive antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). Dihydro-β-carotene hydrobromide showed selectivity to α4β4 and α4β2nAChR, with IC50 of 0.19 and 0.37 μM, respectively.

Before systemic nicotine injection (0.2 μg/kg; SC), dihydro-hydrobromide-β-carotene hydrobromide (DHβE hydrobromide; 10 nmol /0.5 μL) was injected into each area. DHβE was injected into the ventral tegmental area (VTA), nucleus accumbens (NAcc), or lower extremity (IL) cortex, but did not enter the forelimb (PrL) cortex, thereby weakening the response of nicotine to condition enhancers (CRf). Co-administration of dihydro-hydrobromide-β-carotene (5.0 mg/kg; subcutaneous injection) with nicotine (0.2 and 0.4 mg/kg; subcutaneous injection) can prevent the development of conditioned taste aversion (CTAs).