Repeated administration of histamine improves memory retrieval of inhibitory avoidance by lithium in mice.
The influence of repeated administration of histamine on lithium-induced state dependency has been investigated. A single-trial step-down inhibitory avoidance task was used to assess memory in adult male NMRI mice. Intraperitoneal (i.p.) administration of lithium (10 mg/kg), immediately after training (post-training), impaired inhibitory avoidance memory on the test day. Pre-test administration of lithium reversed amnesia induced by the drug given after training, with the maximum response at a dose of 10 mg/kg. Repeated intracerebroventricular (i.c.v.) administration of histamine (20 microg/mouse) for 3 consecutive days followed by 5 days of no drug treatment improved memory retrieval of inhibitory avoidance by a pre-test lower dose (5 mg/kg i.p.) of lithium. In contrast, 3 days of i.c.v. injections of both the histamine H1 receptor antagonist pyrilamine (40 microg/mouse) and the histamine H2 receptor antagonist ranitidine (6.25 and 12.5 microg/mouse) prevented the improving effect of pre-test lithium (10 mg/kg i.p.) on memory retrieval. The results suggest that the repeated administration of histaminergic agents may induce a sensitization which affects the memory impairment induced by lithium.
Department of Pharmacology, School of Medicine and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran. zarinmr@ams.ac.ir
Mohammad Reza
MR
Zarrindast
Leila
L
Parsaei
Shamseddin
S
Ahmadi
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006632:Histamine / Q000008:administration & dosage*; D008094:Lithium / Q000633:toxicity*; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D051379:Mice
D006632:Histamine; D008094:Lithium