HRH3 and schizophrenia: This is evident from the possible modulation of PPI, which has been regarded as an endophenotype of schizophrenia, by interventions at the dopamine, NMDA, 5HT2C, CB1 cannabinoid, neurotensin-1, adenosine A(2A), alpha-7 nicotinic and histamine H3 receptors, revealing the participation of these diverse receptor systems in shaping a single disease phenotype74.