The effects of histaminergic agents in the ventral hippocampus of rats in the plus-maze test of anxiety-like behaviours.
It has been suggested that histamine have modulatory influence on anxiety-related behaviours both in animals and humans. Ventral hippocampus (VHC) may also be an important brain site in the modulation of fear or anxiety. In the present study, the effects of histaminergic agents on anxiety-related behaviours in the rats, using plus-maze test has been investigated. Intra-VHC administration of histamine (2.5, 5 and 7.5 microg/rat) decreased %OAT and %OAE but not locomotor activity, showing an anxiogenic response. Pretreatment of animals with either pyrilamine, a H1 receptor antagonist (10 microg/rat), or ranitidine, a H2 receptor antagonist (10 microg/rat) reverse anxiogenic response of histamine (2.5, 5 and 7.5 microg/rat). However, intra-VHC microinjection of higher doses of pyrilamine (40 microg/rat) or ranitidine (20 and 40 microg/rat) alone increased anxiety-like behaviours in rats. Our results showed that histamine may modulate anxiety-like behaviours via H1 and H2 receptors in the ventral hippocampus of the rats.
Rostami
Parvin
P
Department of Physiology, Tarbiat Moallem University, Tehran, Iran.
Hajizadeh-Moghaddam
Akbar
A
Zarrindast
Mohammad-Reza
MR
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology; D018494:Histamine Agents / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008845:Microinjections / Q000379:methods; D011738:Pyrilamine / Q000494:pharmacology*; D011899:Ranitidine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D018494:Histamine Agents; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D006632:Histamine; D011899:Ranitidine; D011738:Pyrilamine