Transient increases of histamine H₁ and H₂ receptor mRNA levels in the rat striatum after the chronic administration of methamphetamine

In our previous studies, we found that behavioral sensitization evoked by repeated administration of methamphetamine (METH) was suppressed by the activation of the histaminergic neuron system in the brain. In continuation of these studies, we measured the levels of H₁ and H₂ receptor mRNAs in the rat striatum by semi-quantitative reverse transcription-polymerase chain reaction. Seven days after the 21 consecutive administrations of METH (4 mg/kg, i.p.), the levels of both H₁ and H₂ receptor mRNAs in the rat striatum increased significantly. However, 1 and 14 days after the last administration, there were no significant changes in levels of either H₁ or H₂ receptor mRNA in the rat striatum. These transient increases of H₁ and H₂ receptor mRNAs may have some relation to chronic METH abuse and its withdrawal. Copyright (C) 1999 Elsevier Science Ireland Ltd.