Influence of Dopamine D1 Receptors of the Dorsal Hippocampus on the Histamine-Induced Anxiety Behavior in Mice

Dopamine receptors and histamine influence anxiety-like behaviors. Furthermore, interaction between histamine and dopaminergic D1 receptors has been demonstrated in the modulation of some behavior. In the present study, we investigated the interaction between histamine and dopaminergic D1 receptors in the dorsal hippocampus in the anxiety behavior. In this experimental study, the elevated plus maze test was used to test anxiety-like behaviors. Mice were anesthetized with intra-peritoneal injection of ketamine hydrochloride, plus xylazine, and two stainless-steel cannuale were placed in the CA1 region of the hippocampus. Two- and one-way analyses of variance (ANOVAs), followed by LSD test, were used for data analysis. All experiments were performed in accordance with the institutional guidelines for animal care and use. Intra-CA1 injection of histamine and D1 dopamine agonist (SKF 38393) and antagonist (SCH23390) induced anxiety. Intra-CA1 injection SKF 38393 or SCH23390 2 min after of effective dose of histamine (10µg/mouse) inhibited anxiogenic effects of histamine. It seems that both histamine and dopaminergic D1 receptors play a part in the modulation of anxiety in the dorsal hippocampus of mice, and that they carry a complex interaction between them.