LHB and nicotine dependence: Of note, the 5-HT2AR seems to be one of the most critical 5-HTRs in modulating LHb neuronal activity also in comparison to 5-HT2CRs. Nevertheless, the effect of acute and chronic nicotine on anatomical distribution of the 5-HT2AR protein in LHb and many other brain areas related to nicotine addiction remains obscure.